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LTC1682/LTC1682-3.3/LTC1682-5 Doubler Charge Pumps with Low Noise Linear Regulator
FEATURES
s s s s s s s s s s s s s
DESCRIPTIO
Low Output Noise: 60VRMS (100kHz BW) Adjustable or Fixed Boosted Output Adjustable Output Voltage Range: 2.5V to 5.5V Fixed Output Voltages: 3.3V, 5V Wide Input Voltage Range: 1.8V to 4.4V Uses Small Ceramic Capacitors No Inductors Required Output Current up to 50mA 550kHz Switching Frequency Low Operating Current: 150A Low Shutdown Current: 1A Internal Thermal Shutdown and Current Limiting Available in 8-Pin MSOP and SO Packages
APPLICATIO S
s s s s s s
VCO Power Supplies in Cellular Phones 2-Way Pagers Wireless PCMCIA Cards Portable Medical Instruments Low Power Data Acquisition Remote Transmitters
The LTC(R)1682/LTC1682-3.3/LTC1682-5 are doubler charge pumps with an internal low noise, low dropout (LDO) linear regulator. These parts are designed to provide a low noise boosted supply voltage for powering noise sensitive devices such as high frequency VCOs in wireless applications. An internal doubler charge pump converts a 1.8V to 4.4V input to a boosted output, while the internal LDO regulator converts the boosted voltage to a low noise regulated output. The adjustable version allows the user to set VOUT via external resistors connected to FB. The regulator is capable of supplying up to 50mA of output current. Shutdown reduces the supply current to < 5A, removes the load from VIN by disabling the regulator and discharges VOUT to ground through a 100 switch. The LTC1682 LDO regulator is stable with only 2F on the output. Small ceramic capacitors can be used, reducing PC board area. The LTC1682/LTC1682-3.3/LTC1682-5 are short-circuit and over temperature protected. The parts are available in 8-pin MSOP and SO packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
4.2V VCO Power Supply, VIN = 2.5V to 4.4V
SHUTDOWN 8 4.7F 7 VIN 2.5V TO 4.4V 6 0.22F 4.7F 5 C- GND 4 C+ VIN SHDN LTC1682 FB 36k 3 15k 1F 1k 1000pF 1000pF 4.7F
1682 TA01
CPO
VOUT
1 2
4.2V 4.7F 1000pF B P VCO MURATA MQE001-902 M C
fOUT 902MHz 100k VC
AMPLITUDE 10dB/DIV
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Open-Loop Close-In Phase Noise
CENTER = 902MHz SPAN = 100kHz SWP = 10 sec RES BW = 1kHz VBW = 30Hz REF = 0dBm
1682 TA02
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LTC1682/LTC1682-3.3/LTC1682-5
ABSOLUTE MAXIMUM RATINGS
VIN to Ground ..............................................- 0.3V to 5V VOUT Voltage ................................................- 0.3V to 6V CPO to Ground ........................................................ 10V SHDN, FILT/FB Voltage to Ground ..................................... - 0.3V to (VIN + 0.3V) VOUT Short-Circuit Duration ............................ Indefinite IOUT ...................................................................... 90mA
PACKAGE/ORDER INFORMATION
ORDER PART NUMBER
TOP VIEW VOUT SHDN FILT/FB* GND 1 2 3 4 8 7 6 5 CPO C+ VIN C-
MS8 PACKAGE 8-LEAD PLASTIC MSOP *PIN3 = FILT FOR LTC1682-3.3/LTC1682-5 = FB FOR LTC1682
TJMAX = 125C, JA = 140C/ W
LTC1682CMS8 LTC1682CMS8-3.3 LTC1682CMS8-5 LTC1682IMS8 LTC1682IMS8-3.3 LTC1682IMS8-5 MS8 PART MARKING LTER LTGT LTGV LTHM LTGU LTGW
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
PARAMETER VIN Operating Voltage CONDITIONS LTC1682 LTC1682-3.3 LTC1682-5 SHDN = 0V
The q denotes specifications that apply over the full operating temperature range, otherwise specifications are TA = 25C. SHDN = VIN = 3V; C1 = 0.22F; C2, C3, C4 = 4.7F, unless otherwise noted.
MIN
q q q q
TM
IVIN Shutdown Current IVIN Operating Current
IOUT = 0mA, Burst Mode Operation 0C to 70C - 40C to 85C LTC1682, FB = 1.235V LTC1682 LTC1682-3.3, IOUT = 1mA LTC1682-5, IOUT = 1mA IOUT > 200A, VIN = 1.8V to 4.4V
FB Input Current FB Voltage Regulated Output Voltage VOUT Temperature Coefficient Charge Pump Oscillator Frequency
Burst Mode is a trademark of Linear Technology Corporation.
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(Note 1)
Operating Temperature Range Commercial ............................................ 0C to 70C Extended Commercial (Note 2) ........... - 40C to 85C Industrial ........................................... - 40C to 85C Storage Temperature Range ................. - 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C Maximum Junction Temperature .......................... 125C
ORDER PART NUMBER
TOP VIEW VOUT 1 SHDN 2 FILT/FB* 3 GND 4 8 7 6 5 CPO C+ VIN C-
S8 PACKAGE 8-LEAD PLASTIC SO *PIN3 = FILT FOR LTC1682-3.3/LTC1682-5 = FB FOR LTC1682
TJMAX = 125C, JA = 120C/ W
LTC1682CS8 LTC1682CS8-3.3 LTC1682CS8-5 LTC1682IS8 LTC1682IS8-3.3 LTC1682IS8-5 S8 PART MARKING 1682 168233 16825 1682I 1682I33 1682I5
TYP
MAX 4.4 4.4 4.4
UNITS V V V A A A nA V V V ppm kHz
1.8 2 2.7 1 150 150 - 50 1.210 3.23 4.9 480 1.235 3.30 5.0 50 550
5 250 300 50 1.260 3.37 5.1 620
q q q q q q
q
LTC1682/LTC1682-3.3/LTC1682-5
ELECTRICAL CHARACTERISTICS
PARAMETER CPO (Charge Pump Output) Output Resistance VOUT Dropout Voltage (Note 3) CONDITIONS VIN = 1.8V, IOUT = 10mA VIN = 3V, IOUT = 10mA VIN = 4.4V, IOUT = 10mA
The q denotes specifications that apply over the full operating temperature range, otherwise specifications are TA = 25C. SHDN = VIN = 3V; C1 = 0.22F; C2, C3, C4 = 4.7F, unless otherwise noted.
MIN
q q q q q q
TYP 18 13 11 100 75 50 2 88 800 58 500 64 600
MAX 30 20 17 160 120 90
UNITS mV mV mV ms VRMS VP-P VRMS VP-P VRMS VP-P
LTC1682, IOUT = 10mA, VOUT = 2.57V (Note 5) LTC1682/LTC1682-3.3, IOUT = 10mA, VOUT = 3.3V LTC1682/LTC1682-5, IOUT = 10mA, VOUT = 5V IOUT = 10mA LTC1682 LTC1682-3.3 LTC1682-5 IOUT = 10mA, 10Hz f 100kHz, VOUT = 5V IOUT = 10mA, 10Hz f 2.5MHz, VOUT = 5V IOUT = 10mA, 10Hz f 100kHz, CFILT = 1nF IOUT = 10mA, 10Hz f 2.5MHz, CFILT = 1nF IOUT = 10mA, 10Hz f 100kHz, CFILT = 1nF IOUT = 10mA, 10Hz f 2.5MHz, CFILT = 1nF
VOUT Enable Time VOUT Output Noise Voltage
VOUT Line Regulation VOUT Load Regulation VOUT Shutdown Resistance SHDN Input Threshold SHDN Input Current
VIN = 3V to 4V, IOUT = 0mA (Note 6) IOUT = 1mA to 10mA IOUT = 1mA to 50mA (Note 4) SHDN = 0V, Resistance Measured to Ground, VIN = 1.8V SHDN = 0V, Resistance Measured to Ground, VIN = 4.4V VIN = 1.8V to 4.4V SHDN = VIN SHDN = 0V
q q q q q q q
5 3 10 150 50 0.4 -1 -1 1
20 10 350 150 1.6 1 1
mV mV mV V A A
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LTC1682C is guaranteed to meet specified performance from 0C to 70C and is designed, characterized and expected to meet these extended temperature limits, but is not tested at - 40C and 85C. The LTC1682I is guaranteed to meet the extended temperature limits. Note 3: Dropout voltage is the minimum input/output voltage required to maintain regulation at the specified output current. In dropout the output voltage will be equal to: VCPO - VDROPOUT (see Figure 4).
Note 4: Operating conditions are limited by maximum junction temperature. The regulated output specification will not apply for all possible combinations of input voltage and output current. When operating at maximum input voltage, the output current range may be limited. When operating at maximum output current, the input voltage range may be limited. Note 5: Limited by the LDO disable switch point of 1.45VIN. Note 6: The LTC1682 is set to 5V. The feedback current is 25A.
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LTC1682/LTC1682-3.3/LTC1682-5 TYPICAL PERFOR A CE CHARACTERISTICS
CPO Output Resistance vs VIN
35 30 25 TA = 25C C1 = 0.22F IOUT = 10mA 9 TA = 25C 8 7
VCPO (V)
VOUT (mV)
RCPO ()
20 15
4 10 3 5
VCPO = 1.45(VIN)
IOUT (mA)
1.5
2.0
2.5
3.0 VIN (V)
3.5
LTC1682-5 Output Noise (BW = 10Hz to 2.5MHz)
SHDN (V)
2 0 4
SHDN (V)
VOUT 200V/DIV VOUT (V)
2 1
VOUT (V)
100s/DIV CCPO = COUT = 4.7F VOUT = 5V TA = 25C IOUT = 10mA CFILT = 1nF VIN = 3V
Oscillator Frequency vs Temperature
565 VIN = 3V
OSCILLATION FREQUENCY (kHz)
220 200
560
OPERATING CURRENT (A)
555 550 545 540 535 530 -50 -25
4
UW
4.0
Min and Max VCPO vs VIN
10 5 0 -5 -10 (B) 15 10 5 0 4.5
1682 G01
VOUT Transient Response
VCPO = 2(VIN) (A)
6 5
TA = 25C VIN = 3V VOUT = 4V COUT = 10F
1.5
2.0
2.5
3.0 VIN (V)
3.5
4.0
4.5
0
50
100
150 200 TIME (s)
250
300
1682 G02
(A) THE MAXIMUM GENERATED NO LOAD CPO VOLTAGE (B) THE MINIMUM ALLOWABLE CPO VOLTAGE, AT FULL LOAD, TO ENSURE THAT THE LDO IS NOT DISABLED 1682 G02
Shutdown to Enable Timing
2 0 4 TA = 25C VIN = 3V VOUT = 4V IOUT = 10mA CCPO = COUT = 10F 3 2 1 0 200s/DIV
1682 G05
Enable to Shutdown Timing
3
1682 G04
0
NO LOAD TA = 25C VIN = 3V VOUT = 4V COUT = 10F 1ms/DIV
1682 G06
Operating Current vs VIN (No Load)
TA = 25C
180 160 140
LTC1682-3.3 LTC1682-5
LTC1682 120 100 80 60 1.5 2.0 2.5 3.0 VIN (V) 3.5 4.0 4.5
1682 G08
50 25 75 0 TEMPERATURE (C)
100
125
1682 G07
LTC1682/LTC1682-3.3/LTC1682-5 TYPICAL PERFOR A CE CHARACTERISTICS
VOUT Voltage vs Temperature
5.030 VIN = 3V 5.020 IOUT = 10mA 5.010 5.000 LTC1682-5 4.990 3.340 3.330 3.320 LTC1682-3.3 3.310 3.300 3.290 1.240 1.238 LTC1682 1.236 1.234 75 0 50 -50 -25 25 TEMPERATURE (C)
5.000 4.999 4.998 4.997 4.996 4.995 4.994 4.993 3.300 3.299 3.298 3.297 3.296 3.295 3.294 0 5
VOUT VOLTAGE (V)
VOUT VOLTAGE (V)
PIN FUNCTIONS
VOUT (Pin 1): Low Noise Regulated Output Voltage. VOUT should be bypassed with a 2F low ESR capacitor as close to the pin as possible for best performance. The VOUT range is 2.5V to 5.5V. SHDN (Pin 2): Shutdown Input. A logic low on the SHDN pin puts the part in shutdown mode. A logic high enables the part. To continuously enable the part connect SHDN to VIN. When the part is in shutdown, VOUT will be connected to ground via a 100 switch and CPO will be high impedance disconnected from VIN. FB (Pin 3) (LTC1682): The voltage on this pin is compared to the internal reference voltage (1.235V) by the error amplifier to keep the output in regulation. An external resistor divider is required between VOUT and FB to adjust the output voltage. FILT (Pin 3) (LTC1682-3.3/LTC1682-5): This pin is used to filter the internal voltage reference. Typically a 1nF capacitor is connected from FILT to ground. GND (Pin 4): System Ground. C - (Pin 5): Flying Capacitor Negative Input. VIN (Pin 6): Input Voltage, 1.8V to 4.4V. VIN should be bypassed with a 2F low ESR capacitor as close to the pin as possible for best performance. A minimum capacitance value of 0.1F is required. C + (Pin 7): Flying Capacitor Positive Input. CPO (Pin 8): Unregulated Charge Pump Output Voltage. Approximately 1.95(VIN) at low loads. Bypass with a 2F low ESR capacitor. If a minimum VOUT enable time is required, the CPO capacitor should be 2x the VOUT capacitor.
UW
VOUT Voltage vs Output Current
VIN = 3.3V TA = 25C LTC1682-5
LTC1682-3.3
100
125
10 15 20 25 30 35 40 45 50 OUTPUT CURRENT (mA)
1682 G10
1682 G09
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LTC1682/LTC1682-3.3/LTC1682-5
BLOCK DIAGRA SM
C1 0.22F
VIN C4 4.7F
6
CLK1
ENB
SHDN
2
POWERON RESET SD REGEN ENB
550kHz OSCILLATOR
REG B
-
VIN
1:100
+
LDO REGEN
VREF = 1.235V 1A/2A FB
3
4
GND R1
Figure 1. LTC1682 Block Diagram
6
-
+
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C+
7
5
C-
CHARGE PUMP AND SLEW CONTROL
8 275k
CPO C3 4.7F
38k
+ -
328k
1 C2 4.7F SD 100
VOUT
R2
1682 F01
LTC1682/LTC1682-3.3/LTC1682-5
BLOCK DIAGRA SM
VIN C4 4.7F
6
CLK1
ENB
SHDN
2
POWERON RESET SD REGEN ENB
550kHz OSCILLATOR
REG B
3 200k VIN
1nF
REGEN VREF = 1.235V RA 120k/65.5k RB 200k 1A/2A
Figure 2. LTC1682-3.3/LTC1682-5 Block Diagram
+
-
FILT
1:100
LDO
4
GND
-
+
W
C1 0.22F
C+
7
5
C-
CHARGE PUMP AND SLEW CONTROL
8 275k
CPO C3 4.7F
38k
+ -
328k
1
VOUT C2 4.7F
SD 100
1682 F02
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LTC1682/LTC1682-3.3/LTC1682-5
APPLICATIONS INFORMATION
Operation The LTC1682 uses a switched-capacitor charge pump to generate a CPO voltage of approximately 2(VIN). CPO powers an internal low dropout linear regulator that supplies a regulated output at VOUT. Internal comparators are used to sense CPO and VIN voltages for power-up conditioning. The output current is sensed to determine the charge pump operating mode. A trimmed internal bandgap is used as the voltage reference and a trimmed internal oscillator is used to control the charge pump switches. The charge pump is a doubler configuration that uses one external flying capacitor. When enabled, a 2-phase nonoverlapping clock controls the charge pump switches. At start-up, the LDO is disabled and the load is removed from CPO. When CPO reaches 1.75(VIN) the LDO is enabled. If CPO falls below 1.45(VIN) the LDO will be disabled. Generally, the charge pump runs open loop with continuous clocking for low noise. If CPO is greater than 1.95(VIN) and IOUT is less than 100A, the charge pump will operate in Burst Mode operation for increased efficiency but slightly higher output noise. In Burst Mode operation, the clock is disabled when CPO reaches 1.95(VIN) and enabled when CPO droops by about 100mV. The switching frequency is precisely controlled to ensure that the frequency is above 455kHz and at the optimum rate to ensure maximum efficiency. The switch edge rates are also controlled to minimize noise. The effective output resistance at CPO is dependent on the voltage at VIN, CPO and the junction temperature. A low ESR capacitor of 2F should be used at CPO for minimum noise. The LDO is used to filter the ripple on CPO and to set an output voltage independent of CPO. VOUT is set by an external or internal resistor divider. The LDO requires a capacitor on VOUT for stability and improved load transient response. A low ESR capacitor of 2F should be used. Output Voltage Selection The LTC1682-3.3/LTC1682-5 versions have internal resistor networks to set the regulated output voltage. The LTC1682 output voltage is set using an external resistor divider (see Figure 3). The output voltage is determined using the following formula: VOUT = 1.235V(1 + R1/R2) The output voltage range is 2.5V to 5.5V. Maximum VOUT and IOUT Calculations The maximum available output voltage and current can be calculated based on the open circuit CPO voltage, the dropout voltage of the LDO and the effective output resistance of the charge pump. The open circuit CPO voltage is approximately 2(VIN) (see Figure 4).
RCPO VCPO RDROPOUT
EXTERNAL LDO C3 4.7F IN 3.3V C5 OUT GND VIN 3.6V C4 4.7F
Figure 3. Powering an Auxiliary Regulator from CPO
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2VIN CCPO
VDROPOUT ILOAD
1682 F04
-
VOUT
Figure 4. Equivalent Circuit
8 7 6 C1 0.22F 5
CPO C+ VIN C-
VOUT SHDN
1 2 R1 56k C2 4.7F
5.1V VRIPPLE = 800VP-P
LTC1682 FB GND
3 4
VOUT = 1.235V(1 + R1/R2) R2 18k
1682 F03
LTC1682/LTC1682-3.3/LTC1682-5
APPLICATIONS INFORMATION
The following formula can be used to find the maximum output voltage that may be programmed for a given minimum input voltage and output current load: VOUT(MAX) = (2)(VIN(MIN)) - (IOUT)(RCPO) - VDROPOUT with the condition that (IOUT)(RCPO) < 0.55VIN. Example: VIN(MIN) = 3V IOUT = 10mA RCPO(MAX) = 20 Max unloaded CPO voltage = 6V Loaded CPO voltage = 6V - (10mA)(20) = 5.8V VDROPOUT(MAX) = 0.08V VOUT(MAX) = (6V) - (0.2V) - (0.08V) = 5.72V VOUT < 5.5V and (IOUT)(RCPO) < 0.55VIN, 0.2V < 1.65V. For minimum noise applications, the LDO must be kept out of dropout to prevent CPO noise from coupling into VOUT. External CPO Loading The CPO output can drive an external load (an LDO, for example). The current required by this additional load will reduce the available current from VOUT. If the external load requires 5mA, then the maximum available current at VOUT will be reduced by 5mA. Short-Circuit and Thermal Protection VOUT can be shorted to ground indefinitely. Internal circuitry will limit the output current. If the junction temperature exceeds 150C, the part will shut down. Excessive power dissipation due to heavy loads will also cause the part to shut down when the junction temperature exceeds 150C. The part will become enabled when the junction temperature drops below 140C. If the fault condition remains in place, the part will cycle between the shutdown and enabled states. Capacitor Selection For best performance it is recommended that low ESR capacitors be used for C2, C3 and C4 in Figure 1 to reduce noise and ripple. C2 must be 2F and C3 must be equal to or greater than C2. C4 is dependent on the source impedance. The charge pump demands large instantaneous currents which may induce ripple onto a common voltage rail. C4 should be 2F and a spike reducing resistor of 2.2 may be required between VIN and the supply. A low ESR ceramic capacitor is recommended for the flying capacitor C1 with a value of 0.22F. At low load or high VIN a smaller capacitor could be used to reduce ripple on CPO which would reflect as lower ripple on VOUT. If a minimum enable time is required, the CPO output filter capacitor should be at least 2x the VOUT filter capacitor. When the LDO is first enabled, the CPO capacitor will dump a large amount of charge into the VOUT capacitor. If the drop in the CPO voltage falls below 1.45(VIN), the LDO will be disabled and the CPO voltage will have to charge up to 1.75(VIN) to enable the LDO. The resulting cycling extends the enable time. A 1nF filter capacitor for the LTC1682-3.3/LTC1682-5 should be connected between the FILT pin and ground for optimum noise performance. Output Ripple The output noise and ripple on CPO includes a spike component from the charge pump switches and a droop component which is dependent on the load current and the value of C3. The charge pump has been carefully designed to minimize the spike component; however, low ESR capacitors are essential to reduce the remaining spike energy effect on the CPO voltage. C3 should be increased for high load currents to minimize the droop component. Ripple components on CPO are greatly reduced at VOUT by the LDO; however, C2 should also be a low ESR capacitor to improve filtering of the CPO noise. Shutdown When SHDN pin is pulled low (< 0.4V), the part will be in shutdown, the supply current will be < 5A and VOUT will be connected to ground through a 100 switch. In addition, CPO will be high impedance and disconnected from VIN. If shutdown is not required, connect SHDN to VIN which will continuously enable the part.
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LTC1682/LTC1682-3.3/LTC1682-5
APPLICATIONS INFORMATION
Power-On Reset Upon initial power-up, a power-on reset circuit ensures that the internal functions are correctly initialized when power is applied. Once VIN reaches approximately 1V, the power-on reset circuit will enable the part as long as the SHDN pin is held high. Thermal Considerations The power handling capability of the device will be limited by the maximum rated junction temperature (125C). The device power dissipation PD = IOUT (2VIN - V OUT) + VIN(4mA). The device dissipates the majority of its heat through its pins, especially GND (Pin 4). Thermal resistance to ambient can be optimized by connecting GND to a large copper region on the PCB, which serves as a heat sink. Applications which operate the LTC1682 near maximum power levels should maximize the copper area at all pins except C +, C - and FILT/FB and ensure that there is some airflow over the part to carry away excess heat.
VOUT 1 SHDN CFILT 2 LTC1682-3.3/5 3 4 6 5 C4 8 7 VIN
C2
BNC CABLES OR COUPLERS BATTERY OR LOW NOISE DC POWER SUPPLY LTC1682 VOUT DEMO BOARD
COUPLING CAPACITOR
CONNECT BNC AND RLOAD GROUND TO THE OUTPUT CAPACITOR GROUND TERMINAL E5
R* PLACE COUPLING CAPACITOR IN SHIELDED BOX WITH COAXIAL CONNECTOR
Figure 6. LTC1682 Noise Measurement Test Setup
10
-
RLOAD
R*
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General Layout Considerations Due to the high switching frequency and high transient currents produced by the device, careful board layout is a must. A clean board layout using a ground plane and short connections to all capacitors will improve noise performance and ensure proper regulation (Figure 5). The FILT pin on the LTC1682-3.3/LTC1682-5 is a high impedance node. Leakage currents at this pin must be minimized. Measuring Output Noise Measuring the LTC1682 low noise levels requires care. Figure 6 shows a test setup for taking the measurement. Good connection and signal handling technique should yield about 500VP-P over a 2.5MHz bandwidth. The noise measurement involves AC coupling the LTC1682 output into the test setup's input and terminating this connection with 50. Coaxial connections must be maintained to preserve measurement integrity.
C3
GND C1
1682 F05
Figure 5
PREAMPLIFIER 1822 20dB R* BANDWIDTH FILTER INPUT OSCILLOSCOPE
1682 F06
PLACE BANDWIDTH FILTER COMPONENTS IN SHIELDED BOX WITH COAXIAL CONNECTORS *50 TERMINATIONS HP-11048C OR EQUIVALENT NOTE: KEEP BNC CONNECTIONS AS SHORT AS POSSIBLE
LTC1682/LTC1682-3.3/LTC1682-5
TYPICAL APPLICATION
3.3V to Low Noise 3.3V Converter
SHUTDOWN 8 C3 4.7F VIN 3.3V 7 6 C4 4.7F C1 0.22F 5 CPO C+ 1 2 3 4 CFILT 1nF C2 4.7F 3.3V VRIPPLE = 500VP-P
PACKAGE DESCRIPTION
0.007 (0.18) 0.021 0.006 (0.53 0.015)
0 - 6 TYP SEATING PLANE 0.012 (0.30) 0.0256 REF (0.65) TYP 0.192 0.004 (4.88 0.10) 0.118 0.004** (3.00 0.102)
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254) 0- 8 TYP
0.016 - 0.050 0.406 - 1.270
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
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SHDN LTC1682-3.3 FILT GND
VIN C-
1682 TA03
Dimensions in inches (millimeters) unless otherwise noted.
MS8 Package 8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
0.118 0.004* (3.00 0.102) 0.040 0.006 (1.02 0.15) 0.034 0.004 (0.86 0.102) 8 76 5
0.006 0.004 (0.15 0.102)
MSOP (MS8) 1197
1
23
4
S8 Package 8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 - 0.197* (4.801 - 5.004) 0.053 - 0.069 (1.346 - 1.752) 0.004 - 0.010 (0.101 - 0.254) 8 7 6 5
0.014 - 0.019 (0.355 - 0.483)
0.050 (1.270) TYP
0.228 - 0.244 (5.791 - 6.197)
0.150 - 0.157** (3.810 - 3.988)
SO8 0996
1
2
3
4
11
LTC1682/LTC1682-3.3/LTC1682-5
TYPICAL APPLICATION
Wide Input Range VCO Supply (VIN > 4.4V)
VIN 3V TO 6V Q1 FMMT3904 8 C3 4.7F D1 1N4148 3V (REQUIRED FOR START-UP) C4 4.7F C1 0.22F 7 6 5 1 2 3
1682 ta04
RELATED PARTS
PART NUMBER LTC1340 LTC1517-X LT1521 LTC1522 LT1761 Series DESCRIPTION Low Noise, Voltage-Boosted Varactor Driver Micropower, Regulated Charge Pump Doubler in SOT-23 300mA Low Dropout Regulator Micropower, Regulated 5V Charge Pump 100mA Low Noise LDO Regulator in SOT-23 COMMENTS Generates 5V Varactor Drive from 3V Supply ICC = 6A; Short Circuit/Thermal Protected Micropower; Good Transient Response Ultralow Power: Typical Operating ICC = 6A ICC = 20A; 20VRMS Output Noise
12
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com
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R1 470 CPO C+ VIN C- VOUT SHDN LTC1682-5 FILT GND
5V LOW NOISE C2 4.7F
SHUTDOWN
VCO
4
CFILT 1nF
128235fs, sn128235 LT/TP 0799 4K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1999

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Price & Availability of LTC1682IMS8-5

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