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Final Electrical Specifications
LTC1682/LTC1682-3.3/LTC1682-5 Doubler Charge Pumps with Low Noise Linear Regulator
February 1999
FEATURES
s s s s s s s s s s s s s
DESCRIPTION
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.
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
APPLICATIONS
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VCO Power Supplies in Cellular Phones 2-Way Pagers Wireless PCMCIA Cards Portable Medical Instruments Low Power Data Acquisition Remote Transmitters
TYPICAL APPLICATION
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
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.
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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
1
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 ...................................................................... 75mA
PACKAGE/ORDER INFORMATION
ORDER PART NUMBER
TOP VIEW
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
LTC1682CMS8 LTC1682CMS8-3.3 LTC1682CMS8-5 LTC1682IMS8 LTC1682IMS8-3.3 LTC1682IMS8-5 MS8 PART MARKING LTER LTGT LTGV LTHM LTGU LTGW
TJMAX = 125C, JA = 140C/ W
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
SHDN = VIN = 3V; C1 = 0.22F; C2, C3, C4 = 4.7F, TA = 25C unless otherwise noted.
PARAMETER VIN Operating Voltage CONDITIONS LTC1682 LTC1682-3.3 LTC1682-5 SHDN = 0V IOUT = 0mA, Burst ModeTM 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
q q q q q q q q q q
IVIN Shutdown Current IVIN Operating Current
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
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
LTC1682CS8 LTC1682CS8-3.3 LTC1682CS8-5 LTC1682IS8 LTC1682IS8-3.3 LTC1682IS8-5 S8 PART MARKING 1682 168233 16825 1682I 1682I33 1682I5
TJMAX = 125C, JA = 120C/ W
MIN 1.8 2 2.7
TYP
MAX 4.4 4.4 4.4
UNITS V V V A A A nA V V V ppm kHz
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
LTC1682/LTC1682-3.3/LTC1682-5
ELECTRICAL CHARACTERISTICS
SHDN = VIN = 3V; C1 = 0.22F; C2, C3, C4 = 4.7F, TA = 25C unless otherwise noted.
PARAMETER CPO Output Resistance CONDITIONS VIN = 1.8V, IOUT = 10mA VIN = 3V, IOUT = 10mA VIN = 4.4V, IOUT = 10mA 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 VOUT Line Regulation VOUT Load Regulation VOUT Shutdown Resistance 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
q q q q q q q q q q
MIN
TYP 18 13 11 100 75 50 2 88 800 58 500 64 600 5 3 10 150 50
MAX 30 20 17 160 120 90
UNITS mV mV mV ms VRMS VP-P VRMS VP-P VRMS VP-P
VOUT Dropout Voltage (Note 3)
VOUT Enable Time VOUT Output Noise Voltage
VIN = 3V to 4V, IOUT = 1mA 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
20 10 350 150 1.6 1 1
mV mV mV V A A
SHDN Input Threshold SHDN Input Current
q q q
0.4 -1 -1
1
The q denotes specifications that apply over the full operating temperature range. 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.
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LTC1682/LTC1682-3.3/LTC1682-5 TYPICAL PERFORMANCE CHARACTERISTICS
CPO Output Resistance vs VIN
35 30 25
RCPO () VCPO (V)
9 8 7 6 5 VCPO = 2(VIN) (A) (B) VCPO = 1.45(VIN)
VOUT (mV)
20 15
IOUT (mA)
10
3
5
1.5
2.0
2.5
3.0 VIN (V)
3.5
LTC1682-5 Output Noise (BW = 10Hz to 2.5MHz)
SHDN (V)
0 4
SHDN (V)
VOUT 200V/DIV
VOUT (V)
2 1
VOUT (V)
100s/DIV CCPO = COUT = 4.7F IOUT = 10mA VIN = 3V VOUT = 5V TA = 25C CFILT = 1nF
Oscillator Frequency vs Temperature
565 VIN = 3V
220 200
OSCILLATION FREQUENCY (kHz)
560 OPERATING CURRENT (A) 555 550 545 540 535 530 -50 -25
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UW
4.0
Min and Max VCPO vs VIN
10
TA = 25C
VOUT Transient Response
5 0 -5 -10 15 10 5 0 0 50 100 150 200 TIME (s) 250 300
1682 G02
TA = 25C C1 = 0.22F IOUT = 10mA
TA = 25C VIN = 3V VOUT = 4V COUT = 10F
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4.5
1682 G05
1.5
2.0
2.5
3.0 VIN (V)
3.5
4.0
4.5
(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 G04
Shutdown to Enable Timing
2 2 0 4 TA = 25C VIN = 3V VOUT = 4V IOUT = 10mA CCPO = COUT = 10F 3 2 1 0 200s/DIV
1682 G08
1682 G06
Enable to Shutdown Timing
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0
NO LOAD TA = 25C VIN = 3V VOUT = 4V COUT = 10F 1ms/DIV
1682 G09
Operating Current vs VIN (No Load)
TA = 25C
180 160 140
LTC1682-3.3 LTC1682-5
LTC1682 120 100 80
50 25 75 0 TEMPERATURE (C)
100
125
60 1.5
2.0
2.5
3.0 3.5 VIN (V)
4.0
4.5
1682 G12
1682 G11
LTC1682/LTC1682-3.3/LTC1682-5
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): Boosted Unregulated 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.
BLOCK DIAGRA SM
C+ 7
VIN C4 4.7F
6
CLK1
ENB
SHDN
2
POWERON RESET SD REGEN ENB
550kHz OSCILLATOR
REG B
-
VIN
1:100
+
REGEN SD 1A/2A FB GND 100
VREF = 1.235V
3
4
Figure 1. LTC1682 Block Diagram
-
+
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C1 0.22F
5
C-
CHARGE PUMP AND SLEW CONTROL
8 275k
CPO C3 4.7F
38k
+ -
328k
1 C2 4.7F
VOUT
R1
R2
1682 F01
5
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
6
+
-
FILT
1:100
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
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.
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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8 7 6 C1 0.22F 5
CPO C+ VIN C-
VOUT SHDN
1 2 C2 4.7F
5.1V VRIPPLE = 800VP-P
LTC1682 FB GND
3 4
R1 56k VOUT = (1.235V)[1 + (R1/R2)] R2 18k
1682 F03
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LTC1682/LTC1682-3.3/LTC1682-5
APPLICATIONS INFORMATION
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). 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 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.
RCPO
VCPO
RDROPOUT
+ + -
2VIN CCPO
VDROPOUT ILOAD
1682 F04
-
VOUT
Figure 4. Equivalent Circuit
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
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LTC1682/LTC1682-3.3/LTC1682-5
APPLICATIONS INFORMATION
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 = 0V, 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. 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 = IOUT(2VIN - VOUT) + 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. For layout assistance in situations where power dissipation may be a concern, contact the LTC Applications Department. 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. The FILT pin on the LTC1682-3.3/LTC1682-5 is a high impedance node. Leakage currents at this pin must be minimized.
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 1 2 3 4 CFILT 1nF C2 4.7F 3.3V VRIPPLE = 500VP-P
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VOUT
C+ SHDN LTC1682-3.3 VIN C- FILT GND
1682 TA03
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LTC1682/LTC1682-3.3/LTC1682-5
PACKAGE DESCRIPTION
0.007 (0.18) 0.021 0.006 (0.53 0.015)
* 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
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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) 8 76 5
0.192 0.004 (4.88 0.10)
0.118 0.004** (3.00 0.102)
1 0.040 0.006 (1.02 0.15) 0 - 6 TYP SEATING PLANE 0.012 (0.30) 0.0256 REF (0.65) TYP
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4 0.034 0.004 (0.86 0.102)
0.006 0.004 (0.15 0.102)
MSOP (MS8) 1197
LTC1682/LTC1682-3.3/LTC1682-5
PACKAGE DESCRIPTION
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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Dimensions in inches (millimeters) unless otherwise noted.
S8 Package 8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 - 0.197* (4.801 - 5.004) 8 7 6 5
0.228 - 0.244 (5.791 - 6.197)
0.150 - 0.157** (3.810 - 3.988)
1 0.053 - 0.069 (1.346 - 1.752)
2
3
4
0.004 - 0.010 (0.101 - 0.254)
0.014 - 0.019 (0.355 - 0.483)
0.050 (1.270) TYP
SO8 0996
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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 LT1521 LTC1522 LT1761 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
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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 FILT GND
5V LOW NOISE C2 4.7F
SHUTDOWN
VCO
LTC1682-5
4
CFILT 1nF
1286i LT/TP 0299 4K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1999

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