LTC1682/LTC1682-3.3/LTC1682-5 Doubler Charge Pumps with Low Noise Linear Regulator U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO Low Output Noise: 60µVRMS (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: 150µA Low Shutdown Current: 1µA Internal Thermal Shutdown and Current Limiting Available in 8-Pin MSOP and SO Packages U APPLICATIO S ■ ■ ■ ■ ■ ■ VCO Power Supplies in Cellular Phones 2-Way Pagers Wireless PCMCIA Cards Portable Medical Instruments Low Power Data Acquisition Remote Transmitters The LTC®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 < 5µA, removes the load from VIN by disabling the regulator and discharges VOUT to ground through a 100Ω switch. The LTC1682 LDO regulator is stable with only 2µF 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. U TYPICAL APPLICATIO Open-Loop Close-In Phase Noise 4.2V VCO Power Supply, VIN = 2.5V to 4.4V SHUTDOWN 8 CPO VOUT 4.7µF 7 VIN 2.5V TO 4.4V 6 C+ 1 4.7µF 2 SHDN 36k LTC1682 VIN FB C– GND 3 0.22µF 4.7µF 5 4.2V 4 1000pF B P VCO MURATA MQE001-902 M C fOUT 902MHz AMPLITUDE 10dB/DIV 100k VC 1µF 15k 1k 1000pF 1000pF 4.7µF 1682 TA01 CENTER = 902MHz SPAN = 100kHz SWP = 10 sec RES BW = 1kHz VBW = 30Hz REF = 0dBm 1682 TA02 1 LTC1682/LTC1682-3.3/LTC1682-5 W W U W ABSOLUTE MAXIMUM RATINGS (Note 1) 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 Operating Temperature Range Commercial ............................................ 0°C to 70°C Extended Commercial (Note 2) ........... – 40°C to 85°C Industrial ........................................... – 40°C to 85°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C Maximum Junction Temperature .......................... 125°C U W U PACKAGE/ORDER INFORMATION ORDER PART NUMBER LTC1682CMS8 LTC1682CMS8-3.3 LTC1682CMS8-5 LTC1682IMS8 LTC1682IMS8-3.3 LTC1682IMS8-5 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 = 125°C, θJA = 140°C/ W MS8 PART MARKING LTER LTGT LTGV LTHM LTGU LTGW ORDER PART NUMBER TOP VIEW VOUT 1 8 CPO SHDN 2 7 C+ FILT/FB* 3 6 VIN GND 4 5 C– LTC1682CS8 LTC1682CS8-3.3 LTC1682CS8-5 LTC1682IS8 LTC1682IS8-3.3 LTC1682IS8-5 S8 PACKAGE 8-LEAD PLASTIC SO *PIN3 = FILT FOR LTC1682-3.3/LTC1682-5 = FB FOR LTC1682 TJMAX = 125°C, θJA = 120°C/ W S8 PART MARKING 1682 168233 16825 1682I 1682I33 1682I5 Consult factory for Military grade parts. ELECTRICAL CHARACTERISTICS The ● denotes specifications that apply over the full operating temperature range, otherwise specifications are TA = 25°C. SHDN = VIN = 3V; C1 = 0.22µF; C2, C3, C4 = 4.7µF, unless otherwise noted. PARAMETER CONDITIONS VIN Operating Voltage LTC1682 LTC1682-3.3 LTC1682-5 IVIN Shutdown Current SHDN = 0V MIN ● ● ● TYP 1.8 2 2.7 MAX UNITS 4.4 4.4 4.4 V V V ● 1 5 µA IOUT = 0mA, Burst Mode Operation 0°C to 70°C – 40°C to 85°C ● ● 150 150 250 300 µA µA FB Input Current LTC1682, FB = 1.235V ● – 50 50 nA FB Voltage LTC1682 ● 1.210 1.235 1.260 V Regulated Output Voltage LTC1682-3.3, IOUT = 1mA LTC1682-5, IOUT = 1mA ● ● 3.23 4.9 3.30 5.0 3.37 5.1 V V IOUT > 200µA, VIN = 1.8V to 4.4V ● 480 IVIN Operating Current TM ±50 VOUT Temperature Coefficient Charge Pump Oscillator Frequency Burst Mode is a trademark of Linear Technology Corporation. 2 550 ppm 620 kHz LTC1682/LTC1682-3.3/LTC1682-5 ELECTRICAL CHARACTERISTICS The ● denotes specifications that apply over the full operating temperature range, otherwise specifications are TA = 25°C. SHDN = VIN = 3V; C1 = 0.22µF; C2, C3, C4 = 4.7µF, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS CPO (Charge Pump Output) Output Resistance VIN = 1.8V, IOUT = 10mA VIN = 3V, IOUT = 10mA VIN = 4.4V, IOUT = 10mA ● ● ● 18 13 11 30 20 17 Ω Ω Ω VOUT Dropout Voltage (Note 3) LTC1682, IOUT = 10mA, VOUT = 2.57V (Note 5) LTC1682/LTC1682-3.3, IOUT = 10mA, VOUT = 3.3V LTC1682/LTC1682-5, IOUT = 10mA, VOUT = 5V ● ● ● 100 75 50 160 120 90 mV mV mV VOUT Enable Time IOUT = 10mA VOUT Output Noise Voltage LTC1682 IOUT = 10mA, 10Hz ≤ f ≤ 100kHz, VOUT = 5V IOUT = 10mA, 10Hz ≤ f ≤ 2.5MHz, VOUT = 5V 88 800 µVRMS µVP-P LTC1682-3.3 IOUT = 10mA, 10Hz ≤ f ≤ 100kHz, CFILT = 1nF IOUT = 10mA, 10Hz ≤ f ≤ 2.5MHz, CFILT = 1nF 58 500 µVRMS µVP-P LTC1682-5 IOUT = 10mA, 10Hz ≤ f ≤ 100kHz, CFILT = 1nF IOUT = 10mA, 10Hz ≤ f ≤ 2.5MHz, CFILT = 1nF 64 600 µVRMS µVP-P 2 ms VOUT Line Regulation VIN = 3V to 4V, IOUT = 0mA (Note 6) ● 5 20 mV VOUT Load Regulation IOUT = 1mA to 10mA IOUT = 1mA to 50mA (Note 4) ● 3 10 10 mV mV VOUT Shutdown Resistance SHDN = 0V, Resistance Measured to Ground, VIN = 1.8V SHDN = 0V, Resistance Measured to Ground, VIN = 4.4V ● ● 150 50 350 150 Ω Ω SHDN Input Threshold VIN = 1.8V to 4.4V ● 0.4 1 1.6 V SHDN Input Current SHDN = VIN SHDN = 0V ● ● –1 –1 1 1 µA µA 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 0°C to 70°C and is designed, characterized and expected to meet these extended temperature limits, but is not tested at – 40°C and 85°C. 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 25µA. 3 LTC1682/LTC1682-3.3/LTC1682-5 U W TYPICAL PERFOR A CE CHARACTERISTICS 9 TA = 25°C C1 = 0.22µF IOUT = 10mA 10 TA = 25°C 8 VCPO = 2(VIN) 7 VCPO (V) 25 20 5 ∆VOUT (mV) 30 RCPO (Ω) VOUT Transient Response Min and Max VCPO vs VIN CPO Output Resistance vs VIN 35 0 (A) 6 TA = 25°C VIN = 3V VOUT = 4V COUT = 10µF –5 –10 (B) 5 15 IOUT (mA) 15 VCPO = 1.45(VIN) 4 10 10 5 3 0 2.5 2.0 3.0 VIN (V) 3.5 4.0 1.5 4.5 1682 G01 2.0 2.5 3.0 VIN (V) 4.0 3.5 0 4.5 LTC1682-5 Output Noise (BW = 10Hz to 2.5MHz) 100 150 200 TIME (µs) SHDN (V) 0 4 VOUT (V) 1682 G04 2 2 0 4 TA = 25°C VIN = 3V VOUT = 4V IOUT = 10mA CCPO = COUT = 10µF 3 2 1 1 0 0 NO LOAD TA = 25°C VIN = 3V VOUT = 4V COUT = 10µF 1ms/DIV 200µs/DIV 1682 G05 220 565 200 560 OPERATING CURRENT (µA) OSCILLATION FREQUENCY (kHz) VIN = 3V 555 550 545 540 535 180 160 TA = 25°C LTC1682-3.3 LTC1682-5 140 LTC1682 120 100 80 50 25 75 0 TEMPERATURE (°C) 100 125 1682 G07 4 1682 G06 Operating Current vs VIN (No Load) Oscillator Frequency vs Temperature 530 –50 –25 300 Enable to Shutdown Timing 2 3 250 1682 G02 Shutdown to Enable Timing VOUT 200µV/DIV 100µs/DIV CCPO = COUT = 4.7µF VOUT = 5V TA = 25°C IOUT = 10mA CFILT = 1nF VIN = 3V 50 (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 SHDN (V) 1.5 VOUT (V) 5 60 1.5 2.0 2.5 3.0 VIN (V) 3.5 4.0 4.5 1682 G08 LTC1682/LTC1682-3.3/LTC1682-5 U W TYPICAL PERFOR A CE CHARACTERISTICS VOUT Voltage vs Output Current VOUT VOLTAGE (V) VOUT VOLTAGE (V) 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) 100 125 5.000 4.999 4.998 4.997 4.996 4.995 4.994 4.993 VIN = 3.3V TA = 25°C LTC1682-5 3.300 3.299 3.298 3.297 3.296 3.295 3.294 LTC1682-3.3 0 5 10 15 20 25 30 35 40 45 50 OUTPUT CURRENT (mA) 1682 G09 1682 G10 U U U PIN FUNCTIONS VOUT (Pin 1): Low Noise Regulated Output Voltage. VOUT should be bypassed with a ≥ 2µF low ESR capacitor as close to the pin as possible for best performance. The VOUT range is 2.5V to 5.5V. 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. 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 100Ω switch and CPO will be high impedance disconnected from VIN. C – (Pin 5): Flying Capacitor Negative Input. 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. GND (Pin 4): System Ground. VIN (Pin 6): Input Voltage, 1.8V to 4.4V. VIN should be bypassed with a ≥ 2µF low ESR capacitor as close to the pin as possible for best performance. A minimum capacitance value of 0.1µF 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 ≥ 2µF low ESR capacitor. If a minimum VOUT enable time is required, the CPO capacitor should be 2× the VOUT capacitor. 5 LTC1682/LTC1682-3.3/LTC1682-5 W BLOCK DIAGRA SM C1 0.22µF C+ 5 C– CHARGE PUMP AND SLEW CONTROL C4 4.7µF 8 ENB CLK1 CPO C3 4.7µF 275k – 6 VIN 7 + 38k SHDN 2 + POWERON RESET 550kHz OSCILLATOR REG B – SD 328k REGEN ENB 1:100 – + VIN 1 VOUT LDO C2 4.7µF REGEN SD VREF = 1.235V 100Ω 1µA/2µA 3 FB 4 GND R1 R2 1682 F01 Figure 1. LTC1682 Block Diagram 6 LTC1682/LTC1682-3.3/LTC1682-5 W BLOCK DIAGRA SM C1 0.22µF C+ 5 C– CHARGE PUMP AND SLEW CONTROL C4 4.7µF 8 CPO C3 4.7µF 275k – 6 VIN 7 ENB CLK1 + 38k SHDN 2 + POWERON RESET 550kHz OSCILLATOR REG B – SD FILT 1nF 328k REGEN ENB – 3 200k 1:100 + VIN 1 VOUT LDO C2 4.7µF REGEN SD VREF = 1.235V RA 120k/65.5k RB 200k 100Ω 1µA/2µA 4 1682 F02 GND Figure 2. LTC1682-3.3/LTC1682-5 Block Diagram 7 LTC1682/LTC1682-3.3/LTC1682-5 U W U U APPLICATIONS INFORMATION Operation 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 ≥ 2µF should be used. 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. 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: 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 100µA, 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 ≥ 2µF should be used at CPO for minimum noise. EXTERNAL LDO 8 C3 4.7µF 7 IN 3.3V C5 OUT GND VIN 3.6V C4 4.7µF 6 C1 0.22µF 5 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 + + – – VOUT VDROPOUT 2VIN CCPO ILOAD 1682 F04 Figure 4. Equivalent Circuit CPO C+ VOUT SHDN LTC1682 VIN C– FB GND 1 C2 4.7µF 2 3 4 5.1V VRIPPLE = 800µVP-P R1 56k VOUT = 1.235V(1 + R1/R2) R2 18k 1682 F03 Figure 3. Powering an Auxiliary Regulator from CPO 8 RDROPOUT VCPO LTC1682/LTC1682-3.3/LTC1682-5 U W U U 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) = 20Ω Max unloaded CPO voltage = 6V Loaded CPO voltage = 6V – (10mA)(20Ω) = 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 150°C, 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 150°C. The part will become enabled when the junction temperature drops below 140°C. 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 ≥ 2µF 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 ≥ 2µF and a spike reducing resistor of 2.2Ω may be required between VIN and the supply. A low ESR ceramic capacitor is recommended for the flying capacitor C1 with a value of 0.22µF. 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 2× 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 < 5µA and VOUT will be connected to ground through a 100Ω 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. 9 LTC1682/LTC1682-3.3/LTC1682-5 U U W U APPLICATIONS INFORMATION Power-On Reset General Layout Considerations 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. 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). Thermal Considerations The FILT pin on the LTC1682-3.3/LTC1682-5 is a high impedance node. Leakage currents at this pin must be minimized. The power handling capability of the device will be limited by the maximum rated junction temperature (125°C). 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. C2 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 500µVP-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 50Ω. Coaxial connections must be maintained to preserve measurement integrity. VOUT C3 1 SHDN 8 7 VIN 2 LTC1682-3.3/5 CFILT 3 6 4 5 C4 GND C1 1682 F05 Figure 5 BNC CABLES OR COUPLERS BATTERY OR LOW NOISE DC POWER SUPPLY COUPLING CAPACITOR PREAMPLIFIER 1822 LTC1682 VOUT DEMO BOARD + RLOAD CONNECT BNC AND RLOAD GROUND TO THE OUTPUT CAPACITOR GROUND TERMINAL E5 – R* BANDWIDTH FILTER 20dB OSCILLOSCOPE R* 1682 F06 PLACE BANDWIDTH FILTER COMPONENTS IN SHIELDED BOX WITH COAXIAL CONNECTORS R* PLACE COUPLING CAPACITOR IN SHIELDED BOX WITH COAXIAL CONNECTOR *50Ω TERMINATIONS HP-11048C OR EQUIVALENT NOTE: KEEP BNC CONNECTIONS AS SHORT AS POSSIBLE Figure 6. LTC1682 Noise Measurement Test Setup 10 INPUT LTC1682/LTC1682-3.3/LTC1682-5 U TYPICAL APPLICATION 3.3V to Low Noise 3.3V Converter SHUTDOWN 8 C3 4.7µF VIN 3.3V 7 6 C4 4.7µF C1 0.22µF 5 CPO VOUT C+ SHDN LTC1682-3.3 VIN C– FILT GND 1 C2 4.7µF 2 3.3V VRIPPLE = 500µVP-P 3 CFILT 1nF 4 1682 TA03 U PACKAGE DESCRIPTION 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) 0.007 (0.18) 0.034 ± 0.004 (0.86 ± 0.102) 8 7 6 5 0° – 6° TYP SEATING PLANE 0.012 (0.30) 0.0256 REF (0.65) TYP 0.021 ± 0.006 (0.53 ± 0.015) 0.006 ± 0.004 (0.15 ± 0.102) 0.118 ± 0.004** (3.00 ± 0.102) 0.192 ± 0.004 (4.88 ± 0.10) MSOP (MS8) 1197 1 * 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 2 3 4 S8 Package 8-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) 0.189 – 0.197* (4.801 – 5.004) 0.010 – 0.020 × 45° (0.254 – 0.508) 0.008 – 0.010 (0.203 – 0.254) 0.053 – 0.069 (1.346 – 1.752) 0.004 – 0.010 (0.101 – 0.254) 8 7 6 5 0°– 8° TYP 0.016 – 0.050 0.406 – 1.270 0.014 – 0.019 (0.355 – 0.483) *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 0.050 (1.270) TYP 0.150 – 0.157** (3.810 – 3.988) 0.228 – 0.244 (5.791 – 6.197) SO8 0996 1 2 3 4 11 LTC1682/LTC1682-3.3/LTC1682-5 U TYPICAL APPLICATION Wide Input Range VCO Supply (VIN > 4.4V) VIN 3V TO 6V Q1 FMMT3904 R1 470Ω 8 C3 4.7µF D1 1N4148 3V (REQUIRED FOR START-UP) C4 4.7µF 7 6 C1 0.22µF 5 CPO C+ VOUT SHDN LTC1682-5 VIN C– FILT GND 5V LOW NOISE 1 2 SHUTDOWN C2 4.7µF VCO 3 1682 ta04 4 CFILT 1nF RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC1340 Low Noise, Voltage-Boosted Varactor Driver Generates 5V Varactor Drive from 3V Supply LTC1517-X Micropower, Regulated Charge Pump Doubler in SOT-23 ICC = 6µA; Short Circuit/Thermal Protected LT1521 300mA Low Dropout Regulator Micropower; Good Transient Response LTC1522 Micropower, Regulated 5V Charge Pump Ultralow Power: Typical Operating ICC = 6µA LT1761 Series 100mA Low Noise LDO Regulator in SOT-23 ICC = 20µA; 20µVRMS Output Noise 12 Linear Technology Corporation 128235fs, sn128235 LT/TP 0799 4K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com LINEAR TECHNOLOGY CORPORATION 1999