 |
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
| Datasheet File OCR Text: |
| LTC2232/LTC2233 10-Bit,105Msps/ 80Msps ADCs FEATURES DESCRIPTIO Sample Rate: 105Msps/80Msps 61dB SNR up to 140MHz Input 75dB SFDR up to 200MHz Input 775MHz Full Power Bandwidth S/H Single 3.3V Supply Low Power Dissipation: 475mW/366mW Selectable Input Ranges: 0.5V or 1V No Missing Codes Optional Clock Duty Cycle Stabilizer Shutdown and Nap Modes Data Ready Output Clock Pin Compatible Family 135Msps: LTC2224 (12-Bit), LTC2234 (10-Bit) 105Msps: LTC2222 (12-Bit), LTC2232 (10-Bit) 80Msps: LTC2223 (12-Bit), LTC2233 (10-Bit) 48-Pin 7mm x 7mm QFN Package The LTC(R)2232 and LTC2233 are 105Msps/80Msps, sampling 10-bit A/D converters designed for digitizing high frequency, wide dynamic range signals. The LTC2232/ LTC2233 are perfect for demanding communications applications with AC performance that includes 61dB SNR and 75dB spurious free dynamic range for signals up to 200MHz. Ultralow jitter of 0.15psRMS allows undersampling of IF frequencies with excellent noise performance. DC specs include 0.15LSB INL (typ), 0.1LSB DNL (typ) and 0.8LSB INL, 0.6LSB DNL over temperature. The transition noise is a low 0.12LSBRMS. A separate output power supply allows the outputs to drive 0.5V to 3.3V logic. The ENC+ and ENC - inputs may be driven differentially or single ended with a sine wave, PECL, LVDS, TTL, or CMOS inputs. An optional clock duty cycle stabilizer allows high performance at full speed for a wide range of clock duty cycles. APPLICATIO S Wireless and Wired Broadband Communication Cable Head-End Systems Power Amplifier Linearization Communications Test Equipment , LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATIO REFH REFL FLEXIBLE REFERENCE 3.3V VDD 0.5V TO 3.3V OVDD ANALOG INPUT INPUT S/H - 10-BIT PIPELINED ADC CORE CORRECTION LOGIC OUTPUT DRIVERS SFDR (dBFS) + D9 * * * D0 OGND CLOCK/DUTY CYCLE CONTROL 22323 TA01 ENCODE INPUT 22323f U SFDR vs Input Frequency 90 85 4th OR HIGHER 80 75 70 2nd OR 3rd 65 60 55 50 0 100 200 300 400 500 600 INPUT FREQUENCY (MHz) 22323 TA01b U U 1 LTC2232/LTC2233 ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO TOP VIEW 48 GND 47 VDD 46 VDD 45 GND 44 VCM 43 SENSE 42 MODE 41 OF 40 D9 39 D8 38 OGND 37 OVDD OVDD = VDD (Notes 1, 2) Supply Voltage (VDD) ................................................. 4V Digital Output Ground Voltage (OGND) ....... -0.3V to 1V Analog Input Voltage (Note 3) ..... -0.3V to (VDD + 0.3V) Digital Input Voltage .................... -0.3V to (VDD + 0.3V) Digital Output Voltage ............... -0.3V to (OVDD + 0.3V) Power Dissipation ............................................ 1500mW Operating Temperature Range LTC2232C, LTC2233C ............................. 0C to 70C LTC2232I, LTC2233I ...........................-40C to 85C Storage Temperature Range ..................-65C to 125C AIN+ 1 AIN- 2 REFHA 3 REFHA 4 REFLB 5 REFLB 6 REFHB 7 REFHB 8 REFLA 9 REFLA 10 VDD 11 VDD 12 49 36 D7 35 D6 34 D5 33 OVDD 32 OGND 31 D4 30 D3 29 D2 28 OVDD 27 OGND 26 D1 25 D0 UK PACKAGE 48-LEAD (7mm x 7mm) PLASTIC QFN EXPOSED PAD IS GND (PIN 49), MUST BE SOLDERED TO PCB TJMAX = 125C, JA = 29C/W ORDER PART NUMBER LTC2232CUK LTC2232IUK LTC2233CUK LTC2233IUK *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for parts specified with wider operating temperature ranges. CO VERTER CHARACTERISTICS PARAMETER Resolution (No Missing Codes) Integral Linearity Error (Note 5) Differential Linearity Error Integral Linearity Error (Note 5) Differential Linearity Error Offset Error (Note 6) Gain Error Offset Drift Full-Scale Drift Transition Noise The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. (Note 4) CONDITIONS GND 13 VDD 14 GND 15 ENC + 16 ENC - 17 SHDN 18 OE 19 CLOCKOUT 20 NC 21 OGND 22 OVDD 23 NC 24 UK PART MARKING* LTC2232UK LTC2232UK LTC2233UK LTC2233UK MIN 10 -0.8 -0.6 TYP 0.15 0.1 0.5 0.1 MAX 0.8 0.6 UNITS Bits LSB LSB LSB LSB Differential Analog Input Differential Analog Input Single-Ended Analog Input Single-Ended Analog Input -37 -2.5 5 0.5 10 30 15 0.12 37 2.5 External Reference Internal Reference External Reference SENSE = 1V %FS V/C ppm/C ppm/C LSBRMS 22323f 2 U mV W U U WW W U LTC2232/LTC2233 A ALOG I PUT SYMBOL VIN VIN, CM IIN ISENSE IMODE tAP tJITTER CMRR The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. (Note 4) PARAMETER Analog Input Range (AIN+ - AIN-) Analog Input Common Mode Analog Input Leakage Current SENSE Input Leakage MODE Pin Pull-Down Current to GND Full Power Bandwidth Sample and Hold Acquisition Delay Time Sample and Hold Acquisition Delay Time Jitter Analog Input Common Mode Rejection Ratio Figure 8 Test Circuit CONDITIONS 3.1V < VDD < 3.5V Differential Input 0 < AIN+, AIN- < VDD 0V < SENSE < 1V DY A IC ACCURACY SYMBOL SNR PARAMETER Signal-to-Noise Ratio The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. AIN = -1dBFS. (Note 4) CONDITIONS 30MHz Input (1V Range) 30MHz Input (2V Range) 70MHz Input (1V Range) 70MHz Input (2V Range) 140MHz Input (1V Range) 140MHz Input (2V Range) 250MHz Input (1V Range) 250MHz Input (2V Range) SFDR Spurious Free Dynamic Range 30MHz Input (1V Range) 30MHz Input (2V Range) 70MHz Input (1V Range) 70MHz Input (2V Range) 140MHz Input (1V Range) 140MHz Input (2V Range) 250MHz Input (1V Range) 250MHz Input (2V Range) SFDR Spurious Free Dynamic Range 4th Harmonic or Higher 30MHz Input (1V Range) 30MHz Input (2V Range) 70MHz Input (1V Range) 70MHz Input (2V Range) 140MHz Input (1V Range) 140MHz Input (2V Range) 250MHz Input (1V Range) 250MHz Input (2V Range) S/(N+D) Signal-to-Noise Plus Distortion Ratio 30MHz Input (1V Range) 30MHz Input (2V Range) 70MHz Input (1V Range) 70MHz Input (2V Range) IMD Intermodulation Distortion fIN1 = 138MHz, fIN2 = 140MHz U WU U MIN 1 -1 -1 TYP 0.5 to 1 1.6 MAX 1.9 1 1 UNITS V V A A A MHz ns psRMS dB 10 775 0 0.15 80 MIN 60.4 LTC2232 TYP MAX 59.8 61.3 59.8 61.2 59.8 61.2 59.6 61.1 MIN 60.4 LTC2233 TYP MAX 59.9 61.3 59.8 61.3 59.8 61.2 59.7 61.2 UNITS dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dBc 69 80 78 80 78 78 78 71 70 86 86 86 86 86 86 86 86 69 80 78 80 78 78 78 73 72 86 86 86 86 86 86 86 86 60.2 59.8 61.3 59.8 61.2 81 60.2 59.9 61.3 59.8 61.2 81 22323f 3 LTC2232/LTC2233 I TER AL REFERE CE CHARACTERISTICS PARAMETER VCM Output Voltage VCM Output Tempco VCM Line Regulation VCM Output Resistance 3.1V < VDD < 3.5V -1mA < IOUT < 1mA CONDITIONS IOUT = 0 DIGITAL I PUTS A D DIGITAL OUTPUTS SYMBOL VID VICM RIN CIN VIH VIL IIN CIN LOGIC OUTPUTS OVDD = 3.3V COZ ISOURCE ISINK VOH VOL OVDD = 2.5V VOH VOL OVDD = 1.8V VOH VOL High Level Output Voltage Low Level Output Voltage IO = -200A IO = 1.6mA High Level Output Voltage Low Level Output Voltage IO = -200A IO = 1.6mA Hi-Z Output Capacitance Output Source Current Output Sink Current High Level Output Voltage Low Level Output Voltage OE = High (Note 7) VOUT = 0V VOUT = 3.3V IO = -10A IO = -200A IO = 10A IO = 1.6mA PARAMETER Differential Input Voltage Common Mode Input Voltage Input Resistance Input Capacitance High Level Input Voltage Low Level Input Voltage Input Current Input Capacitance (Note 7) VDD = 3.3V VDD = 3.3V VIN = 0V to VDD (Note 7) CONDITIONS ENCODE INPUTS (ENC +, ENC -) The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. (Note 4) MIN LOGIC INPUTS (OE, SHDN) 4 U U U U U (Note 4) MIN 1.570 TYP 1.600 25 3 4 MAX 1.630 UNITS V ppm/C mV/V TYP MAX UNITS V 0.2 1.1 1.6 1.6 6 3 2 0.8 -10 3 10 2.5 Internally Set Externally Set (Note 7) V V k pF V V A pF 3 50 50 pF mA mA V V 0.4 V V V V V V 3.1 3.295 3.29 0.005 0.09 2.49 0.09 1.79 0.09 22323f LTC2232/LTC2233 The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. (Note 9) SYMBOL VDD OVDD IVDD PDISS PSHDN PNAP PARAMETER Analog Supply Voltage Output Supply Voltage Analog Supply Current Power Dissipation Shutdown Power Nap Mode Power SHDN = H, OE = H, No CLK SHDN = H, OE = L, No CLK CONDITIONS POWER REQUIRE E TS The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. (Note 4) SYMBOL fS tL tH tAP tD tC tOE Pipeline Latency Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: All voltage values are with respect to ground with GND and OGND wired together (unless otherwise noted). Note 3: When these pin voltages are taken below GND or above VDD, they will be clamped by internal diodes. This product can handle input currents of greater than 100mA below GND or above VDD without latchup. Note 4: VDD = 3.3V, fSAMPLE = 105MHz (LTC2232) or 80MHz (LTC2233), differential ENC+/ENC- = 2VP-P sine wave, input range = 2VP-P with differential drive, unless otherwise noted. PARAMETER Sampling Frequency ENC Low Time (Note 8) ENC High Time (Note 8) Sample-and-Hold Aperture Delay ENC to DATA Delay ENC to CLOCKOUT Delay DATA to CLOCKOUT Skew Output Enable Delay (Note 7) (Note 7) (tC - tD) (Note 7) (Note 7) TI I G CHARACTERISTICS UW MIN 3.1 0.5 LTC2232 TYP MAX 3.3 3.3 144 475 2 35 3.5 3.6 162 535 MIN 3.1 0.5 LTC2233 TYP MAX 3.3 3.3 111 366 2 35 3.5 3.6 123 406 UNITS V V mA mW mW mW UW CONDITIONS MIN 1 4.5 3 4.5 3 1.3 1.3 - 0.6 LTC2232 TYP MAX 105 4.76 4.76 4.76 4.76 0 2.1 2.1 0 5 5 4 4 0.6 10 500 500 500 500 MIN 1 5.9 3 5.9 3 1.3 1.3 -0.6 LTC2233 TYP MAX 80 6.25 6.25 6.25 6.25 0 2.1 2.1 0 5 5 4 4 0.6 10 500 500 500 500 UNITS MHz ns ns ns ns ns ns ns ns ns Cycles Duty Cycle Stabilizer Off Duty Cycle Stabilizer On Duty Cycle Stabilizer Off Duty Cycle Stabilizer On Note 5: Integral nonlinearity is defined as the deviation of a code from a straight line passing through the actual endpoints of the transfer curve. The deviation is measured from the center of the quantization band. Note 6: Offset error is the offset voltage measured from -0.5 LSB when the output code flickers between 00 0000 0000 and 11 1111 1111 in 2's complement output mode. Note 7: Guaranteed by design, not subject to test. Note 8: Recommended operating conditions. Note 9: VDD = 3.3V, fSAMPLE = 105MHz (LTC2232) or 80MHz (LTC2233), differential ENC+/ENC- = 2VP-P sine wave, input range = 1VP-P with differential drive. 22323f 5 LTC2232/LTC2233 TYPICAL PERFOR A CE CHARACTERISTICS LTC2232: INL, 2V Range 1.0 0.8 0.6 0.4 ERROR (LSB) ERROR (LSB) 0.2 0 - 0.2 - 0.4 - 0.6 - 0.8 - 1.0 0 256 768 512 OUTPUT CODE 1024 2232 G01 0.2 0 - 0.2 - 0.4 - 0.6 - 0.8 - 1.0 0 256 768 512 OUTPUT CODE 1024 2232 G02 SNR (dBFS) LTC2232: SNR vs Input Frequency, -1dB, 1V Range 65 64 63 62 SFDR (dBFS) 61 60 59 58 57 56 55 0 100 300 400 500 600 200 2232 G04 INPUT FREQUENCY (MHz) 55 50 90 85 80 70 65 60 SFDR (dBFS) SNR (dBFS) LTC2232: SFDR (HD4+) vs Input Frequency, -1dB, 2V Range 90 85 80 SFDR (dBFS) SFDR (dBFS) 75 70 65 60 55 50 0 100 200 300 400 500 600 2232 G07 INPUT FREQUENCY (MHz) 90 85 SFDR AND SNR (dBFS) 6 UW LTC2232: DNL, 2V Range 1.0 0.8 0.6 0.4 65 64 63 62 61 60 59 58 57 56 55 LTC2232: SNR vs Input Frequency, -1dB, 2V Range 0 100 200 300 400 500 600 2232 G03 INPUT FREQUENCY (MHz) LTC2232: SFDR (HD2 and HD3) vs Input Frequency, -1dB, 2V Range 90 85 80 75 70 65 60 55 0 100 200 300 400 500 600 2232 G05 INPUT FREQUENCY (MHz) 50 LTC2232: SFDR (HD2 and HD3) vs Input Frequency, -1dB, 1V Range 75 0 100 200 300 400 500 600 2232 G06 INPUT FREQUENCY (MHz) LTC2232: SFDR (HD4+) vs Input Frequency, -1dB, 1V Range 85 80 75 70 65 LTC2232: SFDR and SNR vs Sample Rate, 2V Range, fIN = 30MHz, -1dB SFDR 80 75 70 65 60 55 50 0 100 200 300 400 500 600 2232 G08 INPUT FREQUENCY (MHz) SNR 60 55 50 0 20 40 60 80 100 120 2232 G09 SAMPLE RATE (Msps) 22323f LTC2232/LTC2233 TYPICAL PERFOR A CE CHARACTERISTICS LTC2232: SFDR and SNR vs Sample Rate, 1V Range, fIN = 30MHz, -1dB 85 SFDR 80 150 2V RANGE 75 140 8 160 SFDR AND SNR (dBFS) IOVDD (mA) IVDD (mA) 70 65 60 55 SNR 0 20 40 60 80 100 SAMPLE RATE (Msps) LTC2232: SFDR vs Input Level, f IN = 70MHz, 2V Range 90 80 70 dBFS 0 - 10 - 20 - 30 SFDR (dBc AND dBFS) AMPLITUDE (dB) dBc 50 40 30 20 10 0 - 50 - 40 -30 - 20 - 10 INPUT LEVEL (dBFS) 0 2232 G13 - 50 - 60 - 70 - 80 - 90 AMPLITUDE (dB) 60 LTC2232: 8192 Point FFT, f IN = 30MHz, -1dB, 2V Range 0 - 10 - 20 - 30 0 - 10 - 20 - 30 AMPLITUDE (dB) AMPLITUDE (dB) - 50 - 60 - 70 - 80 - 90 - 50 - 60 - 70 - 80 - 90 AMPLITUDE (dB) - 40 - 100 - 110 - 120 0 5 10 15 20 25 30 35 40 45 50 2232 G16 FREQUENCY (MHz) UW 120 2232 G10 LTC2232: IVDD vs Sample Rate, 5MHz Sine Wave Input, -1dB 10 LTC2232: IOVDD vs Sample Rate, 5MHz Sine Wave Input, -1dB, OVDD = 1.8V 6 130 1V RANGE 120 110 100 4 2 0 20 60 80 40 SAMPLE RATE (Msps) 100 120 0 0 20 2232 G11 40 60 80 SAMPLE RATE (Msps) 100 120 2232 G12 LTC2232: 8192 Point FFT, f IN = 5MHz, -1dB, 2V Range 0 - 10 - 20 - 30 - 40 - 50 - 60 - 70 - 80 - 90 - 100 - 110 0 5 10 15 20 25 30 35 40 45 50 2232 G14 FREQUENCY (MHz) - 120 LTC2232: 8192 Point FFT, f IN = 5MHz, -1dB,1V Range - 40 - 100 - 110 - 120 0 5 10 15 20 25 30 35 40 45 50 2232 G15 FREQUENCY (MHz) LTC2232: 8192 Point FFT, f IN = 30MHz, -1dB, 1V Range 0 - 10 - 20 - 30 - 40 - 50 - 60 - 70 - 80 - 90 - 100 - 110 0 5 10 15 20 25 30 35 40 45 50 2232 G17 FREQUENCY (MHz) - 120 0 LTC2232: 8192 Point FFT, f IN = 70MHz, -1dB, 2V Range - 40 - 100 - 110 - 120 5 10 15 20 25 30 35 40 45 50 2232 G18 FREQUENCY (MHz) 22323f 7 LTC2232/LTC2233 TYPICAL PERFOR A CE CHARACTERISTICS LTC2232: 8192 Point FFT, f IN = 70MHz, -1dB, 1V Range 0 -10 -20 -30 AMPLITUDE (dB) AMPLITUDE (dB) -50 -60 -70 -80 -90 -50 -60 -70 -80 -90 AMPLITUDE (dB) -40 -100 -110 -120 0 5 10 15 20 25 30 35 40 45 50 2232 G19 FREQUENCY (MHz) LTC2232: 8192 Point FFT, f IN = 250MHz, -1dB, 2V Range 0 -10 -20 -30 AMPLITUDE (dB) AMPLITUDE (dB) -50 -60 -70 -80 -90 -50 -60 -70 -80 -90 AMPLITUDE (dB) -40 -100 -110 -120 0 5 10 15 20 25 30 35 40 45 50 2232 G22 FREQUENCY (MHz) LTC2232: 8192 Point 2-Tone FFT, f IN = 68MHz and 70MHz, -7dB Each, 2V Range 0 -10 -20 -30 AMPLITUDE (dB) AMPLITUDE (dB) -40 -50 -60 -70 -80 -90 -60 -70 -80 -90 COUNT -100 -110 -120 0 5 10 15 20 25 30 35 40 45 50 2232 G25 FREQUENCY (MHz) 8 UW LTC2232: 8192 Point FFT, f IN = 140MHz, -1dB, 2V Range 0 -10 -20 -30 -40 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 0 5 10 15 20 25 30 35 40 45 50 2232 G20 FREQUENCY (MHz) -120 LTC2232: 8192 Point FFT, f IN = 140MHz, -1dB, 1V Range -100 -110 -120 0 5 10 15 20 25 30 35 40 45 50 2232 G21 FREQUENCY (MHz) LTC2232: 8192 Point FFT, f IN = 250MHz, -1dB, 1V Range 0 -10 -20 -30 -40 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 0 5 10 15 20 25 30 35 40 45 50 2232 G23 FREQUENCY (MHz) -120 LTC2232: 8192 Point FFT, f IN = 500MHz, -6dB, 1V Range -100 -110 -120 0 5 10 15 20 25 30 35 40 45 50 2232 G24 FREQUENCY (MHz) LTC2232: 8192 Point 2-Tone FFT, f IN = 138MHz and 140MHz, -7dB Each, 1V Range 0 -10 -20 -30 -40 -50 120000 100000 80000 60000 40000 20000 140000 LTC2232: Noise Histogram 131071 -100 -110 -120 0 5 10 15 20 25 30 35 40 45 50 2232 G26 FREQUENCY (MHz) 0 0 510 511 CODE 1 512 2232 G27 22323f LTC2232/LTC2233 TYPICAL PERFOR A CE CHARACTERISTICS LTC2233: INL, 2V Range 1.0 0.8 0.6 0.4 1.0 0.8 0.6 0.4 ERROR (LSB) ERROR (LSB) 0.2 0 - 0.2 - 0.4 - 0.6 - 0.8 - 1.0 0 256 768 512 OUTPUT CODE 1024 2233 G01 0.2 0 - 0.2 - 0.4 - 0.6 - 0.8 - 1.0 0 256 768 512 OUTPUT CODE 1024 2233 G02 SNR (dBFS) LTC2233: SNR vs Input Frequency, -1dB, 1V Range 65 64 63 62 90 85 80 SFDR (dBFS) 61 60 59 58 57 56 55 0 100 300 400 500 600 200 2233 G04 INPUT FREQUENCY (MHz) 70 65 60 55 50 0 100 200 300 400 500 600 2233 G05 INPUT FREQUENCY (MHz) SFDR (dBFS) SNR (dBFS) LTC2233: SFDR (HD4+) vs Input Frequency, -1dB, 2V Range 90 85 80 90 85 SFDR AND SNR (dBFS) SFDR (dBFS) SFDR (dBFS) 75 70 65 60 55 50 0 100 200 300 400 500 600 2233 G07 INPUT FREQUENCY (MHz) UW LTC2233: DNL, 2V Range 65 64 63 62 61 60 59 58 57 56 55 LTC2233: SNR vs Input Frequency, -1dB, 2V Range 0 100 300 400 500 600 200 2233 G03 INPUT FREQUENCY (MHz) LTC2233: SFDR (HD2 and HD3) vs Input Frequency, -1dB, 2V Range 90 85 80 75 70 65 60 55 50 LTC2233: SFDR (HD2 and HD3) vs Input Frequency, -1dB, 1V Range 75 0 100 200 300 400 500 600 2233 G06 INPUT FREQUENCY (MHz) LTC2233: SFDR (HD4+) vs Input Frequency, -1dB, 1V Range 85 80 75 70 65 LTC2233: SFDR and SNR vs Sample Rate, 2V Range, fIN = 30MHz, -1dB SFDR 80 75 70 65 60 55 50 0 100 200 300 400 500 600 2233 G08 INPUT FREQUENCY (MHz) SNR 60 55 50 0 20 40 60 80 100 2233 G09 SAMPLE RATE (Msps) 22323f 9 LTC2232/LTC2233 TYPICAL PERFOR A CE CHARACTERISTICS LTC2233: SFDR and SNR vs Sample Rate, 1V Range, fIN = 30MHz, -1dB 85 80 SFDR AND SNR (dBFS) SFDR 120 6 IOVDD (mA) 75 2V RANGE 70 65 60 55 50 0 20 40 60 80 SAMPLE RATE (Msps) 100 2233 G10 IVDD (mA) SNR 2 90 LTC2233: SFDR vs Input Level, f IN = 70MHz, 2V Range 90 80 70 SFDR (dBc AND dBFS) AMPLITUDE (dB) dBFS dBc 50 40 30 20 10 0 -50 -40 -30 -20 -10 INPUT LEVEL (dBFS) 0 2233 G13 -50 -60 -70 -80 -90 AMPLITUDE (dB) 60 LTC2233: 8192 Point FFT, f IN = 30MHz, -1dB, 2V Range 0 -10 -20 -30 AMPLITUDE (dB) AMPLITUDE (dB) -50 -60 -70 -80 -90 -50 -60 -70 -80 -90 AMPLITUDE (dB) -40 -100 -110 -120 0 5 10 15 20 25 30 FREQUENCY (MHz) 35 40 10 UW 2233 G16 LTC2233: IVDD vs Sample Rate, 5MHz Sine Wave Input, -1dB 130 8 LTC2233: IOVDD vs Sample Rate, 5MHz Sine Wave Input, -1dB, OVDD = 1.8V 110 1V RANGE 100 4 80 0 20 60 80 40 SAMPLE RATE (Msps) 100 2233 G11 0 0 20 60 80 40 SAMPLE RATE (Msps) 100 2233 G12 LTC2233: 8192 Point FFT, f IN = 5MHz, -1dB, 2V Range 0 -10 -20 -30 -40 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 0 5 10 15 20 25 30 FREQUENCY (MHz) 35 40 -120 LTC2233: 8192 Point FFT, f IN = 5MHz, -1dB, 1V Range -100 -110 -120 0 5 10 2233 G14 15 20 25 30 FREQUENCY (MHz) 35 40 2233 G15 LTC2233: 8192 Point FFT, f IN = 30MHz, -1dB, 1V Range 0 -10 -20 -30 -40 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 0 5 10 15 20 25 30 FREQUENCY (MHz) 35 40 -120 LTC2233: 8192 Point FFT, f IN = 70MHz, -1dB, 2V Range -100 -110 -120 0 5 10 2233 G17 15 20 25 30 FREQUENCY (MHz) 35 40 2233 G18 22323f LTC2232/LTC2233 TYPICAL PERFOR A CE CHARACTERISTICS LTC2233: 8192 Point FFT, f IN = 70MHz, -1dB, 1V Range 0 -10 -20 -30 AMPLITUDE (dB) AMPLITUDE (dB) -50 -60 -70 -80 -90 -50 -60 -70 -80 -90 AMPLITUDE (dB) -40 -100 -110 -120 0 5 10 15 20 25 30 FREQUENCY (MHz) 35 40 LTC2233: 8192 Point FFT, f IN = 250MHz, -1dB, 2V Range 0 -10 -20 -30 AMPLITUDE (dB) AMPLITUDE (dB) -50 -60 -70 -80 -90 -50 -60 -70 -80 -90 AMPLITUDE (dB) -40 -100 -110 -120 0 5 10 15 20 25 30 FREQUENCY (MHz) 35 40 LTC2233: 8192 Point 2-Tone FFT, f IN = 68MHz and 70MHz, -7dB Each, 2V Range 0 -10 -20 -30 AMPLITUDE (dB) AMPLITUDE (dB) -40 -50 -60 -70 -80 -90 -60 -70 -80 -90 COUNT -100 -110 -120 0 5 10 15 20 25 30 FREQUENCY (MHz) 35 40 UW 2233 G19 2233 G22 2233 G25 LTC2233: 8192 Point FFT, f IN = 140MHz, -1dB, 2V Range 0 -10 -20 -30 -40 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 0 5 10 15 20 25 30 FREQUENCY (MHz) 35 40 -120 LTC2233: 8192 Point FFT, f IN = 140MHz, -1dB, 1V Range -100 -110 -120 0 5 10 2233 G20 15 20 25 30 FREQUENCY (MHz) 35 40 2233 G21 LTC2233: 8192 Point FFT, f IN = 250MHz, -1dB, 1V Range 0 -10 -20 -30 -40 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 0 5 10 15 20 25 30 FREQUENCY (MHz) 35 40 -120 LTC2233: 8192 Point FFT, f IN = 500MHz, -6dB, 1V Range -100 -110 -120 0 5 10 2233 G23 15 20 25 30 FREQUENCY (MHz) 35 40 2233 G24 LTC2233: 8192 Point 2-Tone FFT, f IN = 138MHz and 140MHz, -7dB Each, 1V Range 0 -10 -20 -30 -40 -50 120000 100000 80000 60000 40000 20000 140000 LTC2233: Noise Histogram 131071 -100 -110 -120 0 0 0 5 10 15 20 25 30 FREQUENCY (MHz) 35 40 510 2233 G26 1 511 CODE 512 2233 G27 22323f 11 LTC2232/LTC2233 PI FU CTIO S AIN+ (Pin 1): Positive Differential Analog Input. AIN- (Pin 2): Negative Differential Analog Input. REFHA (Pins 3, 4): ADC High Reference. Bypass to Pins 5, 6 with 0.1F ceramic chip capacitor, to Pins 9, 10 with a 2.2F ceramic capacitor and to ground with a 1F ceramic capacitor. REFLB (Pins 5, 6): ADC Low Reference. Bypass to Pins 5, 6 with 0.1F ceramic chip capacitor. Do not connect to Pins 9, 10. REFHB (Pins 7, 8): ADC High Reference. Bypass to Pins 9, 10 with 0.1F ceramic chip capacitor. Do not connect to Pins 3, 4. REFLA (Pins 9, 10): ADC Low Reference. Bypass to Pins 7, 8 with 0.1F ceramic chip capacitor, to Pins 3, 4 with a 2.2F ceramic capacitor and to ground with a 1F ceramic capacitor. VDD (Pins 11, 12, 14, 46, 47): 3.3V Supply. Bypass to GND with 0.1F ceramic chip capacitors. Adjacent pins can share a bypass capacitor. GND (Pins 13, 15, 45, 48): ADC Power Ground. ENC+ (Pin 16): Encode Input. The input is sampled on the positive edge. ENC- (Pin 17): Encode Complement Input. The input is sampled on the negative edge. Bypass to ground with 0.1F ceramic for single-ended ENCODE signal. SHDN (Pin 18): Shutdown Mode Selection Pin. Connecting SHDN to GND and OE to GND results in normal operation with the outputs enabled. Connecting SHDN to GND and OE to VDD results in normal operation with the outputs at high impedance. Connecting SHDN to VDD and OE to GND results in nap mode with the outputs at high impedance. Connecting SHDN to VDD and OE to VDD results in sleep mode with the outputs at high impedance. OE (Pin 19): Output Enable Pin. Refer to SHDN pin function. CLOCKOUT (Pin 20): Data Valid Output. Latch data on the falling edge of CLKOUT. NC (Pins 21, 24): Do not connect these pins. D0 - D9 (Pins 25, 26, 29, 30, 31, 34, 35, 36, 39, 40): Digital Outputs. D9 is the MSB. OGND (Pins 22, 27, 32, 38): Output Driver Ground. OVDD (Pins 23, 28, 33, 37): Positive Supply for the Output Drivers. Bypass to ground with 0.1F ceramic chip capacitors. OF (Pin 41): Over/Under Flow Output. High when an over or under flow has occurred. MODE (Pin 42): Output Format and Clock Duty Cycle Stabilizer Selection Pin. Connecting MODE to 0V selects straight binary output format and turns the clock duty cycle stabilizer off. Connecting MODE to 1/3 VDD selects straight binary output format and turns the clock duty cycle stabilizer on. Connecting MODE to 2/3 VDD selects 2's complement output format and turns the clock duty cycle stabilizer on. Connecting MODE to VDD selects 2's complement output format and turns the clock duty cycle stabilizer off. SENSE (Pin 43): Reference Programming Pin. Connecting SENSE to VCM selects the internal reference and a 0.5V input range. VDD selects the internal reference and a 1V input range. An external reference greater than 0.5V and less than 1V applied to SENSE selects an input range of VSENSE. 1V is the largest valid input range. VCM (Pin 44): 1.6V Output and Input Common Mode Bias. Bypass to ground with 2.2F ceramic chip capacitor. Exposed Pad (Pin 49): ADC Power Ground. The exposed pad on the bottom of the package needs to be soldered to ground. 12 U U U 22323f LTC2232/LTC2233 FUNCTIONAL BLOCK DIAGRA AIN+ INPUT S/H FIRST PIPELINED ADC STAGE (4 BITS) SECOND PIPELINED ADC STAGE (3 BITS) THIRD PIPELINED ADC STAGE (3 BITS) FOURTH PIPELINED ADC STAGE (3 BITS) FIFTH PIPELINED ADC STAGE (3 BITS) AIN- VCM 2.2F 1.6V REFERENCE SHIFT REGISTER AND CORRECTION RANGE SELECT REFH SENSE REF BUF DIFF REF AMP REFLB REFHA 2.2F 0.1F 1F Figure 1. Functional Block Diagram TI I G DIAGRA S Timing Diagram tAP ANALOG INPUT N N+1 tH tL ENC - ENC + tD D0-D9, OF N-5 N-4 N-3 N-2 N-1 N+2 N+3 N+4 tC CLOCKOUT 22323 TD02 W REFL INTERNAL CLOCK SIGNALS OVDD OF DIFFERENTIAL INPUT LOW JITTER CLOCK DRIVER CONTROL LOGIC OUTPUT DRIVERS * * * D9 D0 CLKOUT REFLA REFHB ENC 0.1F 1F + 22323 F01 W U UW U OGND ENC - M0DE SHDN OE 22323f 13 LTC2232/LTC2233 APPLICATIO S I FOR ATIO DYNAMIC PERFORMANCE Signal-to-Noise Plus Distortion Ratio The signal-to-noise plus distortion ratio [S/(N + D)] is the ratio between the RMS amplitude of the fundamental input frequency and the RMS amplitude of all other frequency components at the ADC output. The output is band limited to frequencies above DC to below half the sampling frequency. Signal-to-Noise Ratio The signal-to-noise ratio (SNR) is the ratio between the RMS amplitude of the fundamental input frequency and the RMS amplitude of all other frequency components except the first five harmonics and DC. Total Harmonic Distortion Total harmonic distortion is the ratio of the RMS sum of all harmonics of the input signal to the fundamental itself. The out-of-band harmonics alias into the frequency band between DC and half the sampling frequency. THD is expressed as: THD = 20Log (V22 + V32 + V42 + . . . Vn2)/V1 where V1 is the RMS amplitude of the fundamental frequency and V2 through Vn are the amplitudes of the second through nth harmonics. The THD calculated in this data sheet uses all the harmonics up to the fifth. Intermodulation Distortion If the ADC input signal consists of more than one spectral component, the ADC transfer function nonlinearity can produce intermodulation distortion (IMD) in addition to THD. IMD is the change in one sinusoidal input caused by the presence of another sinusoidal input at a different frequency. If two pure sine waves of frequencies fa and fb are applied to the ADC input, nonlinearities in the ADC transfer function can create distortion products at the sum and difference frequencies of mfa nfb, where m and n = 0, 1, 2, 3, etc. The 3rd order intermodulation products are 2fa + fb, 2fb + fa, 2fa - fb and 2fb - fa. The intermodulation 14 U distortion is defined as the ratio of the RMS value of either input tone to the RMS value of the largest 3rd order intermodulation product. Spurious Free Dynamic Range (SFDR) Spurious free dynamic range is the peak harmonic or spurious noise that is the largest spectral component excluding the input signal and DC. This value is expressed in decibels relative to the RMS value of a full scale input signal. Input Bandwidth The input bandwidth is that input frequency at which the amplitude of the reconstructed fundamental is reduced by 3dB for a full scale input signal. Aperture Delay Time The time from when a rising ENC+ equals the ENC- voltage to the instant that the input signal is held by the sample and hold circuit. Aperture Delay Jitter The variation in the aperture delay time from conversion to conversion. This random variation will result in noise when sampling an AC input. The signal to noise ratio due to the jitter alone will be: SNRJITTER = -20log (2pi) * fIN * tJITTER CONVERTER OPERATION As shown in Figure 1, the LTC2232/LTC2233 is a CMOS pipelined multistep converter. The converter has five pipelined ADC stages; a sampled analog input will result in a digitized value five cycles later (see the Timing Diagram section). For optimal AC performance the analog inputs should be driven differentially. For cost sensitive applications, the analog inputs can be driven single-ended with slightly worse harmonic distortion. The encode input is differential for improved common mode noise immunity. The LTC2232/LTC2233 has two phases of operation, determined by the state of the differential ENC+/ENC- input pins. For brevity, the text will refer to ENC+ greater than ENC- as ENC high and ENC+ less than ENC- as ENC low. 22323f W U U LTC2232/LTC2233 APPLICATIO S I FOR ATIO Each pipelined stage shown in Figure 1 contains an ADC, a reconstruction DAC and an interstage residue amplifier. In operation, the ADC quantizes the input to the stage and the quantized value is subtracted from the input by the DAC to produce a residue. The residue is amplified and output by the residue amplifier. Successive stages operate out of phase so that when the odd stages are outputting their residue, the even stages are acquiring that residue and vice versa. When ENC is low, the analog input is sampled differentially directly onto the input sample-and-hold capacitors, inside the "Input S/H" shown in the block diagram. At the instant that ENC transitions from low to high, the sampled input is held. While ENC is high, the held input voltage is buffered by the S/H amplifier which drives the first pipelined ADC stage. The first stage acquires the output of the S/H during this high phase of ENC. When ENC goes back low, the first stage produces its residue which is acquired by the second stage. At the same time, the input S/H goes back to acquiring the analog input. When ENC goes back high, the second stage produces its residue which is acquired by the third stage. An identical process is repeated for the third and fourth stages, resulting in a fourth stage residue that is sent to the fifth stage ADC for final evaluation. Each ADC stage following the first has additional range to accommodate flash and amplifier offset errors. Results from all of the ADC stages are digitally synchronized such that the results can be properly combined in the correction logic before being sent to the output buffer. SAMPLE/HOLD OPERATION AND INPUT DRIVE Sample/Hold Operation Figure 2 shows an equivalent circuit for the LTC2232/ LTC2233 CMOS differential sample-and-hold. The analog inputs are connected to the sampling capacitors (CSAMPLE) through NMOS transistors. The capacitors shown attached to each input (CPARASITIC) are the summation of all other capacitance associated with each input. During the sample phase when ENC is low, the transistors connect the analog inputs to the sampling capacitors and they charge to, and track the differential input voltage. U When ENC transitions from low to high, the sampled input voltage is held on the sampling capacitors. During the hold phase when ENC is high, the sampling capacitors are disconnected from the input and the held voltage is passed to the ADC core for processing. As ENC transitions from high to low, the inputs are reconnected to the sampling capacitors to acquire a new sample. Since the sampling capacitors still hold the previous sample, a charging glitch proportional to the change in voltage between samples will be seen at this time. If the change between the last sample and the new sample is small, the charging glitch seen at the input will be small. If the input change is large, such as the change seen with input frequencies near Nyquist, then a larger charging glitch will be seen. LTC2232/LTC2233 VDD 15 CPARASITIC 1pF CSAMPLE 1.6pF CPARASITIC 1pF VDD CSAMPLE 1.6pF AIN+ VDD 15 AIN- 1.6V 6k ENC+ ENC- 6k 1.6V 22323 F02 W U U Figure 2. Equivalent Input Circuit Single-Ended Input For cost sensitive applications, the analog inputs can be driven single-ended. With a single-ended input the harmonic distortion and INL will degrade, but the SNR and DNL will remain unchanged. For a single-ended input, AIN+ should be driven with the input signal and AIN- should be connected to 1.6V or VCM. Common Mode Bias For optimal performance the analog inputs should be driven differentially. Each input should swing 0.5V for the 2V range or 0.25V for the 1V range, around a common mode voltage of 1.6V. The VCM output pin (Pin 44) may be 22323f 15 LTC2232/LTC2233 APPLICATIO S I FOR ATIO used to provide the common mode bias level. VCM can be tied directly to the center tap of a transformer to set the DC input level or as a reference level to an op amp differential driver circuit. The VCM pin must be bypassed to ground close to the ADC with a 2.2F or greater capacitor. Input Drive Impedance As with all high performance, high speed ADCs, the dynamic performance of the LTC2232/LTC2233 can be influenced by the input drive circuitry, particularly the second and third harmonics. Source impedance and input reactance can influence SFDR. At the falling edge of ENC, the sample-and-hold circuit will connect the 1.6pF sampling capacitor to the input pin and start the sampling period. The sampling period ends when ENC rises, holding the sampled input on the sampling capacitor. Ideally the input circuitry should be fast enough to fully charge the sampling capacitor during the sampling period 1/(2FENCODE); however, this is not always possible and the incomplete settling may degrade the SFDR. The sampling glitch has been designed to be as linear as possible to minimize the effects of incomplete settling. For the best performance, it is recommended to have a source impedance of 100 or less for each input. The source impedance should be matched for the differential inputs. Poor matching will result in higher even order harmonics, especially the second. Input Drive Circuits Figure 3 shows the LTC2232/LTC2233 being driven by an RF transformer with a center tapped secondary. The secondary center tap is DC biased with VCM, setting the ADC input signal at its optimum DC level. Figure 3 shows a 1:1 turns ratio transformer. Other turns ratios can be used if the source impedance seen by the ADC does not exceed 100 for each ADC input. A disadvantage of using a transformer is the loss of low frequency response. Most small RF transformers have poor performance at frequencies below 1MHz. Figure 4 demonstrates the use of a differential amplifier to convert a single ended input signal into a differential input signal. The advantage of this method is that it provides low frequency input response; however, the limited gain band- 16 U width of most op amps will limit the SFDR at high input frequencies. Figure 5 shows a single-ended input circuit. The impedance seen by the analog inputs should be matched. This circuit is not recommended if low distortion is required. The 25 resistors and 12pF capacitor on the analog inputs serve two purposes: isolating the drive circuitry from the sample-and-hold charging glitches and limiting the wideband noise at the converter input. For input frequencies higher than 100MHz, the capacitor may need to be decreased to prevent excessive signal loss. VCM 2.2F 0.1F ANALOG INPUT T1 1:1 25 25 25 0.1F AIN+ AIN+ 12pF 25 AIN- AIN- 22323 F03 W UU LTC2232/ LTC2233 T1 = MA/COM ETC1-1T RESISTORS, CAPACITORS ARE 0402 PACKAGE SIZE Figure 3. Single-Ended to Differential Conversion Using a Transformer VCM HIGH SPEED DIFFERENTIAL 25 AMPLIFIER ANALOG INPUT 2.2F AIN+ AIN+ 12pF AIN- AIN- AMPLIFIER = LTC6600-20, AD8138, ETC. 22323 F04 + CM + - 25 LTC2232/ LTC2233 - Figure 4. Differential Drive with an Amplifier VCM 10k 0.1F ANALOG INPUT 10k 25 2.2F AIN+ AIN+ 12pF 25 0.1F AIN- AIN- 22323 F05 LTC2232/ LTC2233 Figure 5. Single-Ended Drive 22323f LTC2232/LTC2233 APPLICATIO S I FOR ATIO The AIN+ and AIN- inputs each have two pins to reduce package inductance. The two AIN+ and the two AIN- pins should be shorted together. For input frequencies above 100MHz the input circuits of Figure 6, 7 and 8 are recommended. The balun transformer gives better high frequency response than a flux coupled center tapped transformer. The coupling capacitors allow the analog inputs to be DC biased at 1.6V. In Figure 8 the series inductors are impedance matching elements that maximize the ADC bandwidth. VCM 2.2F 0.1F ANALOG INPUT 25 T1 0.1F 25 12 12 0.1F AIN+ AIN+ 8pF AIN- AIN- T1 = MA/COM ETC1-1-13 RESISTORS, CAPACITORS ARE 0402 PACKAGE SIZE 22323 F06 LTC2232/ LTC2233 Figure 6. Recommended Front End Circuit for Input Frequencies Between 100MHz and 250MHz VCM 2.2F 0.1F ANALOG INPUT 25 T1 0.1F 25 AIN- AIN- T1 = MA/COM ETC1-1-13 RESISTORS, CAPACITORS ARE 0402 PACKAGE SIZE 22323 F07 AIN+ 0.1F AIN+ LTC2232/ LTC2233 Figure 7. Recommended Front End Circuit for Input Frequencies Between 250MHz and 500MHz VCM 2.2F 0.1F ANALOG INPUT 25 T1 0.1F 25 4.7nH 4.7nH 0.1F AIN+ AIN+ 2pF AIN- AIN- T1 = MA/COM ETC1-1-13 RESISTORS, CAPACITORS ARE 0402 PACKAGE SIZE INDUCTORS 0603 OR 0402 22323 F08 LTC2232/ LTC2233 Figure 8. Recommended Front End Circuit for Input Frequencies Above 500MHz U Reference Operation Figure 9 shows the LTC2232/LTC2233 reference circuitry consisting of a 1.6V bandgap reference, a difference amplifier and switching and control circuit. The internal voltage reference can be configured for two pin selectable input ranges of 2V (1V differential) or 1V (0.5V differential). Tying the SENSE pin to VDD selects the 2V range; typing the SENSE pin to VCM selects the 1V range. The 1.6V bandgap reference serves two functions: its output provides a DC bias point for setting the common mode voltage of any external input circuitry; additionally, the reference is used with a difference amplifier to generate the differential reference levels needed by the internal ADC circuitry. An external bypass capacitor is required for the 1.6V reference output, VCM. This provides a high frequency low impedance path to ground for internal and external circuitry. The difference amplifier generates the high and low reference for the ADC. High speed switching circuits are connected to these outputs and they must be externally bypassed. Each output has four pins: two each of REFHA and REFHB for the high reference and two each of REFLA and REFLB for the low reference. The multiple output pins are needed to reduce package inductance. Bypass capacitors must be connected as shown in Figure 9. LTC2232/LTC2233 1.6V VCM 2.2F 1V RANGE DETECT AND CONTROL SENSE REFLB 0.1F REFHA BUFFER INTERNAL ADC HIGH REFERENCE 0.5V 4 1.6V BANDGAP REFERENCE TIE TO VDD FOR 2V RANGE; TIE TO VCM FOR 1V RANGE; RANGE = 2 * VSENSE FOR 0.5V < VSENSE < 1V 1F 2.2F DIFF AMP 1F REFLA 0.1F REFHB INTERNAL ADC LOW REFERENCE 22323 F09 W UU Figure 9. Equivalent Reference Circuit 22323f 17 LTC2232/LTC2233 APPLICATIO S I FOR ATIO Other voltage ranges in between the pin selectable ranges can be programmed with two external resistors as shown in Figure 10. An external reference can be used by applying its output directly or through a resistor divider to SENSE. It is not recommended to drive the SENSE pin with a logic device. The SENSE pin should be tied to the appropriate level as close to the converter as possible. If the SENSE pin is driven externally, it should be bypassed to ground as close to the device as possible with a 1F ceramic capacitor. 1.6V VCM 2.2F 12k 0.8V 12k SENSE 1F ENC+ 0.1F 22323 F10 LTC2232/ LTC2233 Figure 10. 1.6V Range ADC Input Range The input range can be set based on the application. The 2V input range will provide the best signal-to-noise performance while maintaining excellent SFDR. The 1V input range will have better SFDR performance, but the SNR will degrade by 1.5dB. See the Typical Performance Characteristics section. Driving the Encode Inputs The noise performance of the LTC2232/LTC2233 can depend on the encode signal quality as much as on the analog input. The ENC+/ENC- inputs are intended to be driven differentially, primarily for noise immunity from common mode noise sources. Each input is biased through a 6k resistor to a 1.6V bias. The bias resistors set the DC operating point for transformer coupled drive circuits and can set the logic threshold for single-ended drive circuits. Any noise present on the encode signal will result in additional aperture jitter that will be RMS summed with the inherent ADC aperture jitter. In applications where jitter is critical (high input frequencies) take the following into consideration: 1. Differential drive should be used. 2. Use as large an amplitude as possible; if transformer coupled use a higher turns ratio to increase the amplitude. ENC- 18 U 3. If the ADC is clocked with a sinusoidal signal, filter the encode signal to reduce wideband noise. 4. Balance the capacitance and series resistance at both encode inputs so that any coupled noise will appear at both inputs as common mode noise. The encode inputs have a common mode range of 1.1V to 2.5V. Each input may be driven from ground to VDD for single-ended drive. LTC2232/LTC2233 VDD TO INTERNAL ADC CIRCUITS 1.6V BIAS 6k VDD CLOCK INPUT 50 1:4 VDD 1.6V BIAS 6k 22323 F11 W UU Figure 11. Transformer Driven ENC+/ENC- VTHRESHOLD = 1.6V ENC+ 1.6V ENC- 0.1F 22323 F12a LTC2232/ LTC2233 Figure 12a. Single-Ended ENC Drive, Not Recommended for Low Jitter 3.3V MC100LVELT22 3.3V 130 Q0 130 ENC+ ENC- 83 83 22323 F12b D0 Q0 LTC2232/ LTC2233 Figure 12b. ENC Drive Using a CMOS to PECL Translator 22323f LTC2232/LTC2233 APPLICATIO S I FOR ATIO Maximum and Minimum Encode Rates The maximum encode rate for the LTC2232/LTC2233 is 105Msps (LTC2232) and 80Msps (LTC2233). For the ADC to operate properly, the encode signal should have a 50% (5%) duty cycle. Each half cycle must have at least 4.5ns (LTC2232) or 5.9ns (LTC2233) for the ADC internal circuitry to have enough settling time for proper operation. Achieving a precise 50% duty cycle is easy with differential sinusoidal drive using a transformer or using symmetric differential logic such as PECL or LVDS. An optional clock duty cycle stabilizer circuit can be used if the input clock has a non 50% duty cycle. This circuit uses the rising edge of the ENC+ pin to sample the analog input. The falling edge of ENC+ is ignored and the internal falling edge is generated by a phase-locked loop. The input clock duty cycle can vary from 20% to 80% and the clock duty cycle stabilizer will maintain a constant 50% internal duty cycle. If the clock is turned off for a long period of time, the duty cycle stabilizer circuit will require a hundred clock cycles for the PLL to lock onto the input clock. To use the clock duty cycle stabilizer, the MODE pin should be connected to 1/3VDD or 2/3VDD using external resistors. The lower limit of the LTC2232/LTC2233 sample rate is determined by droop of the sample-and-hold circuits. The pipelined architecture of this ADC relies on storing analog signals on small valued capacitors. Junction leakage will discharge the capacitors. The specified minimum operating frequency for the LTC2232/LTC2233 is 1Msps. DIGITAL OUTPUTS Digital Output Buffers Figure 13 shows an equivalent circuit for a single output buffer. Each buffer is powered by OVDD and OGND, isolated from the ADC power and ground. The additional Nchannel transistor in the output driver allows operation down to low voltages. The internal resistor in series with the output makes the output appear as 50 to external circuitry and may eliminate the need for external damping resistors. U LTC2232/LTC2233 OVDD VDD VDD 0.5V TO VDD 0.1F OVDD DATA FROM LATCH OE OGND PREDRIVER LOGIC 43 TYPICAL DATA OUTPUT 22323 F13 W UU Figure 13. Digital Output Buffer As with all high speed/high resolution converters, the digital output loading can affect the performance. The digital outputs of the LTC2232/LTC2233 should drive a minimal capacitive load to avoid possible interaction between the digital outputs and sensitive input circuitry. The output should be buffered with a device such as an ALVCH16373 CMOS latch. For full speed operation the capacitive load should be kept under 10pF. Lower OVDD voltages will also help reduce interference from the digital outputs. Data Format The LTC2232/LTC2233 parallel digital output can be selected for offset binary or 2's complement format. The format is selected with the MODE pin. Connecting MODE to GND or 1/3VDD selects straight binary output format. Connecting MODE to 2/3VDD or VDD selects 2's complement output format. An external resistor divider can be used to set the 1/3VDD or 2/3VDD logic values. Table 2 shows the logic states for the MODE pin. Table 2. MODE Pin Function MODE Pin 0 1/3VDD 2/3VDD VDD Output Format Straight Binary Straight Binary 2's Complement 2's Complement Clock Duty Cycle Stablizer Off On On Off 22323f 19 LTC2232/LTC2233 APPLICATIO S I FOR ATIO Overflow Bit When OF outputs a logic high the converter is either overranged or underranged. Output Clock The ADC has a delayed version of the ENC+ input available as a digital output, CLKOUT. The CLKOUT pin can be used to synchronize the converter data to the digital system. This is necessary when using a sinusoidal encode. Data will be updated just after CLKOUT rises and can be latched on the falling edge of CLKOUT. Output Driver Power Separate output power and ground pins allow the output drivers to be isolated from the analog circuitry. The power supply for the digital output buffers, OVDD, should be tied to the same power supply as for the logic being driven. For example if the converter is driving a DSP powered by a 1.8V supply then OVDD should be tied to that same 1.8V supply. OVDD can be powered with any voltage up to the VDD of the part. OGND can be powered with any voltage from GND up to 1V and must be less than OVDD. The logic outputs will swing between OGND and OVDD. Output Enable The outputs may be disabled with the output enable pin, OE. OE high disables all data outputs including OF and CLKOUT. The data access and bus relinquish times are too slow to allow the outputs to be enabled and disabled during full speed operation. The output Hi-Z state is intended for use during long periods of inactivity. Sleep and Nap Modes The converter may be placed in shutdown or nap modes to conserve power. Connecting SHDN to GND results in normal operation. Connecting SHDN to VDD and OE to VDD results in sleep mode, which powers down all circuitry including the reference and typically dissipates 1mW. When exiting sleep mode it will take milliseconds for the output data to become valid because the reference capacitors have to recharge and stabilize. Connecting SHDN to VDD and OE 20 U to GND results in nap mode, which typically dissipates 30mW. In nap mode, the on-chip reference circuit is kept on, so that recovery from nap mode is faster than that from sleep mode, typically taking 100 clock cycles. In both sleep and nap mode all digital outputs are disabled and enter the Hi-Z state. GROUNDING AND BYPASSING The LTC2232/LTC2233 requires a printed circuit board with a clean unbroken ground plane. A multilayer board with an internal ground plane is recommended. Layout for the printed circuit board should ensure that digital and analog signal lines are separated as much as possible. In particular, care should be taken not to run any digital track alongside an analog signal track or underneath the ADC. High quality ceramic bypass capacitors should be used at the VDD, OVDD, VCM, REFHA, REFHB, REFLA and REFLB pins as shown in the block diagram on the front page of this data sheet. Bypass capacitors must be located as close to the pins as possible. Of particular importance are the capacitors between REFHA and REFLB and between REFHB and REFLA. These capacitors should be as close to the device as possible (1.5mm or less). Size 0402 ceramic capacitors are recommended. The 2.2F capacitor between REFHA and REFLA can be somewhat further away. The traces connecting the pins and bypass capacitors must be kept short and should be made as wide as possible. The LTC2232/LTC2233 differential inputs should run parallel and close to each other. The input traces should be as short as possible to minimize capacitance and to minimize noise pickup. HEAT TRANSFER Most of the heat generated by the LTC2232/LTC2233 is transferred from the die through the bottom-side exposed pad and package leads onto the printed circuit board. For good electrical and thermal performance, the exposed pad should be soldered to a large grounded pad on the PC board. It is critical that all ground pins are connected to a ground plane of sufficient area. 22323f W UU LTC2232/LTC2233 APPLICATIO S I FOR ATIO Evaluation Circuit Schematic of the LTC2232 VCC CLKOUT JP1 CLKOUT VCC R19 OPT ANALOG INPUT J1 C1 0.1F R1* T1* R2 24.9 C2* R4 24.9 C3 0.1F VCM R5 1k C4 0.1F R6* 1 2 3 4 13 C5 1F C6 0.1F 15 5 C7 2.2F 6 7 8 C8 1F C9 0.1F 9 10 VDD VDD 46 47 11 12 14 CLK SHDN C11 33pF CLK JP2 GND C13 0.1F C15 2.2F 16 17 18 19 44 43 42 C10 0.1F C12 0.1F VDD LTC2232* 20 CLKOUT 21 AIN- D0 24 REFHA D1 25 REFHA D2 26 GND D3 29 GND D4 30 REFLB D5 31 REFLB D6 34 REFHB D7 35 REFHB D8 36 REFLA D9 39 REFLA D10 40 VDD D11 41 VDD OF 37 VDD OVDD 33 VDD OVDD 28 VDD OVDD 23 + ENC OVDD 38 ENC- OGND 32 SHDN OGND 27 OEL OGND 22 VCM OGND 48 SENSE GND 45 MODE GND AIN+ GND 49 JP3 SENSE VDD VDD VCM VCM EXT REF EXT REF R13 1k R14 1k C22 0.1F VCC R12 1k VDD JP4 MODE VDD 2/3VDD C21 0.1F 1/3VDD C24 0.1F C20 0.1F GND C19 0.1F C18 0.1F VDD (2.5V) 1 2 3 4 LT1763 OUT IN ADJ GND GND GND BYP SHDN 8 7 6 5 ENCODE INPUT C23 J3 0.1F R16 100 T2 ETC1-1T CLK R15 100 CLK C34 1F C26 0.1F C27 10F 6.3V R17 105k R18 100k C28 0.01F U 34 45 VCC GND GND GND VCC 2LE 1LE 2OE 1OE 1D1 1D2 1D3 1D4 1D5 1D6 1D7 1D8 2D1 2D2 2D3 2D4 2D5 2D6 2D7 2D8 GND VCC GND GND VCC GND GND VCC 1Q1 1Q2 1Q3 1Q4 1Q5 1Q6 1Q7 1Q8 2Q1 2Q2 2Q3 W UU 28 31 21 15 18 10 4 7 2 3 5 6 8 9 11 12 13 14 16 17 RN1D 33 RN1C 33 RN1B 33 RN1A 33 RN2D 33 RN2C 33 RN2B 33 RN2A 33 RN3D 33 RN3C 33 RN3B 33 RN3A 33 D0 D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 C33 0.1F 1 2 5 NC7SV865X 4 3 R3 33 39 42 25 48 24 1 47 46 44 43 41 40 38 37 36 35 33 32 30 29 27 26 39 37 35 33 31 29 27 25 23 21 19 17 15 13 11 9 7 5 3 C17 0.1F 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 3201S-40G1 2Q4 19 2Q5 20 2Q6 2Q7 2Q8 22 23 PI74VCX16373A VCC NC7SV865X 4 5 1 2 3 C16 0.1F 1 R10 10k R9 10k R8 10k 1 A0 2 A1 3 A2 4 A3 8 VCC 7 WP 6 SCL 5 SDA 24LC025 VDD GND C25 4.7F PWR GND VDD 3.3V VCC C29 0.1F C30 0.1F C31 0.1F C32 0.1F Assembly Type DC751A-A VCC U1 LTC2222 LTC2223 LTC2232 LTC2233 LTC2222 LTC2223 LTC2232 LTC2233 R1, R6 24.9 24.9 24.9 24.9 12.4 12.4 12.4 12.4 C2 12pF 12pF 12pF 12pF 8.2pF 8.2pF 8.2pF 8.2pF T1 ETC1-1T ETC1-1T ETC1-1T ETC1-1T ETC1-1-13 ETC1-1-13 ETC1-1-13 ETC1-1-13 22323f DC751A-B DC751A-C DC751A-D DC751A-E DC751A-F DC751A-G DC751A-H *Depends On Version Type 21 LTC2232/LTC2233 APPLICATIO S I FOR ATIO Layer 1 Component Side Layer 3 Power Plane 22 U Silkscreen Top Layer 2 GND Plane Layer 4 Bottom Side 22323f W UU LTC2232/LTC2233 PACKAGE DESCRIPTIO 0.25 0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 7.00 0.10 (4 SIDES) 0.75 0.05 R = 0.115 TYP PIN 1 TOP MARK (SEE NOTE 5) PIN 1 CHAMFER 0.00 - 0.05 NOTE: 1. DRAWING CONFORMS TO JEDEC PACKAGE OUTLINE MO-220 VARIATION (WKKD-2) 2. ALL DIMENSIONS ARE IN MILLIMETERS 3. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.20mm ON ANY SIDE, IF PRESENT 4. EXPOSED PAD SHALL BE SOLDER PLATED 5. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. U UK Package 48-Lead Plastic QFN (7mm x 7mm) (Reference LTC DWG # 05-08-1704) 0.70 0.05 5.15 0.05 6.10 0.05 7.50 0.05 (4 SIDES) PACKAGE OUTLINE 47 48 0.40 0.10 1 2 5.15 0.10 (4-SIDES) (UK48) QFN 0903 0.200 REF 0.25 0.05 0.50 BSC BOTTOM VIEW--EXPOSED PAD 22323f 23 LTC2232/LTC2233 RELATED PARTS PART NUMBER LTC1747 LTC1748 LTC2220 LTC2221 LTC2222 LTC2223 LTC2230 LTC2231 DESCRIPTION 80Msps, 12-Bit ADC 80Msps, 14-Bit ADC 170Msps, 12-Bit ADC 135Msps, 12-Bit ADC 12-Bit, 105Msps ADC 12-Bit, 80Msps ADC 170Msps, 10-Bit ADC 135Msps, 10-Bit ADC COMMENTS 72dB SNR, 87dB SFDR, 5V Supply, 48-Pin TSSOP Package 76.3dB SNR, 90dB SFDR, 5V Supply, 48-Pin TSSOP Package 67.5dB SNR, 890mW, 3.3V Supply, 9mm x 9mm QFN Package 67.5dB SNR, 660mW, 3.3V Supply, 9mm x 9mm QFN Package 475mW, 67.9dB SNR, 7mm x 7mm QFN Package 366mW, 68dB SNR, 7mm x 7mm QFN Package 61dB SNR, 890mW, 3.3V Supply, 9mm x 9mm QFN Package 61dB SNR, 660mW, 3.3V Supply, 9mm x 9mm QFN Package 22323f 24 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 LT/TP 0804 1K * PRINTED IN USA www.linear.com (c) LINEAR TECHNOLOGY CORPORATION 2004 |
Price & Availability of LTC2232
 |
|
|
|
|
All Rights Reserved © IC-ON-LINE 2003 - 2022 |
| [Add Bookmark] [Contact Us] [Link exchange] [Privacy policy] |
|
Mirror Sites : [www.datasheet.hk]
[www.maxim4u.com] [www.ic-on-line.cn]
[www.ic-on-line.com] [www.ic-on-line.net]
[www.alldatasheet.com.cn]
[www.gdcy.com]
[www.gdcy.net] |