LTC1522CS8#PBF

LTC1522 Micropower, Regulated 5V Charge Pump DC/DC Converter U DESCRIPTION FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Ultralow Power: Typical Operating ICC = 6µA Short-Circuit/Thermal Protected Regulated 5V ±4% Output Voltage 2.7V to 5V Input Range No Inductors Very Low ICC in Shutdown: < 1µA Output Current: 10mA (VIN ≥ 2.7V) 20mA (VIN ≥ 3V) Shutdown Disconnects Load from VIN Internal Oscillator: 700kHz Compact Application Circuit (< 0.1 in2) 8-Pin MSOP and SO Packages U APPLICATIONS ■ ■ ■ ■ SIM Interface Supplies for GSM Cellular Telephones Li-Ion Battery Backup Supplies Local 3V to 5V Conversion Smart Card Readers PCMCIA Local 5V Supplies The LTC1522 has thermal shutdown and can survive a continuous short from VOUT to GND. In shutdown the load is disconnected from VIN. The part is available in 8-pin MSOP and SO packages. The LTC1522 is pin compatible with the LTC1516 in applications where VIN ≥ 2.7V and IOUT ≤ 20mA. , LTC and LT are registered trademarks of Linear Technology Corporation. U ■ The LTC®1522 is a micropower charge pump DC/DC converter that produces a regulated 5V output from a 2.7V to 5V input supply. Extremely low supply current (6µA typical with no load, < 1µA in shutdown) and low external parts count (one 0.22µF flying capacitor and two 10µF capacitors at VIN and VOUT) make the LTC1522 ideally suited for small, light load battery-powered applications. Typical efficiency (VIN = 3V) exceeds 75% with load currents between 50µA and 20mA. Modulating the SHDN pin keeps the typical efficiency above 75% with load currents all the way down to 10µA. TYPICAL APPLICATION Regulated 5V Output from a 2.7V to 5V Input 1 + 10µF 2 3 + 10µF 4 NC NC VIN SHDN LTC1522 VOUT GND C+ C– 8 7 VIN = 3V ON/OFF 6 5 0.22µF VOUT = 5V ±4% IOUT = 0mA TO 10mA, VIN ≥ 2.7V IOUT = 0mA TO 20mA, VIN ≥ 3V 80 EFFICIENCY (%) VIN 2.7V TO 5V Efficiency vs Output Current 90 LOW IQ MODE (SEE FIGURE 2) 70 SHDN = 0V 60 1522 TA01 50 0.01 0.1 1 10 OUTPUT CURRENT (mA) 100 1522 TA02 1 LTC1522 W W U W ABSOLUTE MAXIMUM RATINGS (Note 1) VIN to GND .................................................. – 0.3V to 6V VOUT to GND ............................................... – 0.3V to 6V SHDN to GND ............................................. – 0.3V to 6V VOUT Short-Circuit Duration ............................ Indefinite Commercial Temperature Range ................ 0°C to 70°C Extended Commercial Operating Temperature Range (Note 2) ............. – 40°C to 85°C Storage Temperature Range ................ – 65°C to 150°C Lead Temperature (Soldering, 10 sec)................. 300°C U W U PACKAGE/ORDER INFORMATION ORDER PART NUMBER TOP VIEW NC 1 VIN 2 VOUT 3 C+ 4 8 7 6 5 NC SHDN GND C– MS8 PACKAGE 8-LEAD PLASTIC MSOP LTC1522CMS8 ORDER PART NUMBER TOP VIEW NC 1 8 NC VIN 2 7 SHDN C+ 4 MS8 PART MARKING TJMAX = 125°C, θJA = 160°C/ W LTCG LTC1522CS8 6 GND VOUT 3 5 C– S8 PART MARKING S8 PACKAGE 8-LEAD PLASTIC SO 1522 TJMAX = 125°C, θJA = 150°C/ W Consult factory for Industrial and Military grade parts. ELECTRICAL CHARACTERISTICS VIN = 2.7V to 5V, CFLY = 0.22µF, CIN = COUT = 10µF, TMIN to TMAX unless otherwise specified. (Note 2) SYMBOL PARAMETER VIN Input Voltage VOUT Output Voltage ICC fOSC VIH VIL IIH IIL tON Operating Supply Current Shutdown Supply Current Output Ripple Efficiency Switching Frequency SHDN Input Threshold CONDITIONS ● 2.7V ≤ VIN ≤ 5V, IOUT ≤ 10mA 3V ≤ VIN ≤ 5V, IOUT ≤ 20mA 2.7V ≤ VIN ≤ 5V, IOUT = 0mA, SHDN = 0V 2.7V ≤ VIN ≤ 3.6V, IOUT = 0mA, SHDN = VIN 3.6V < VIN ≤ 5V, IOUT = 0mA, SHDN = VIN VIN = 3V, IOUT = 10mA VIN = 3V, IOUT = 10mA Oscillator Free Running ● ● ● VOUT Turn-On Time 5.0 5.0 6 0.005 VSHDN = VIN VSHDN = 0V VIN = 3V, IOUT = 0mA MAX 5 5.2 5.2 15 1 2.5 70 82 700 ● SHDN Input Current TYP (0.7)(VIN) ● The ● denotes specifications which apply over the specified temperature range. Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. 2 ● ● MIN 2.7 4.8 4.8 ● ● 0.4 –1 –1 1 1 1 UNITS V V V µA µA µA mVP-P % kHz V V µA µA ms Note 2: C grade device specifications are guaranteed over the 0°C to 70°C temperature range. In addition, C grade device specifications are assured over the – 40°C to 85°C temperature range by design or correlation, but are not production tested. LTC1522 U W TYPICAL PERFORMANCE CHARACTERISTICS Output Voltage vs Input Voltage Efficiency vs Input Voltage 250 IOUT = 10mA TA = 25°C IOUT = 10mA COUT = 10µF 80 5.05 TA = 70°C 5.00 TA = 0°C TA = 25°C 70 60 50 4.95 4.90 2.5 3.0 4.0 4.5 3.5 INPUT VOLTAGE (V) 3.0 4.0 4.5 3.5 INPUT VOLTAGE (V) No Load Input Current vs Input Voltage 5.2 OUTPUT VOLTAGE (V) 8 TA = 25°C TA = 0°C 5 4 2.5 4.0 4.5 3.5 INPUT VOLTAGE (V) 5.0 3.0 4.0 4.5 3.5 INPUT VOLTAGE (V) Load Transient Response IOUT 0mA TO 10mA 10mA/DIV 5.1 VOUT AC COUPLED 50mV/DIV 5.0 VIN = 2.7V 4.9 4.8 0 VIN = 3V 40 60 20 OUTPUT CURRENT (mA) 1522 G04 5.0 1522 G03 VIN = 3.3V 3.0 COUT = 22µF 0 2.5 5.0 TA = 25°C CFLY = 0.1µF COUT = 6.8µF IOUT = 0mA 6 COUT = 10µF Typical Output Voltage vs Output Current 9 TA = 70°C COUT = 6.8µF 100 1522 G02 1522 G01 7 COUT = 3.3µF 150 50 40 2.5 5.0 IOUT = 10mA CFLY = 0.1µF TA = 25°C 200 VRIPPLE P-P (mV) EFFICIENCY (%) OUTPUT VOLTAGE (V) 5.10 INPUT CURRENT (µA) Output Ripple vs Input Voltage 90 5.15 VIN = 3V COUT = 10µF 500µs/DIV 1522 G06 80 1522 G05 U U U PIN FUNCTIONS NC (Pin 1): No Connect. C – (Pin 5): Flying Capacitor, Negative Terminal. VIN (Pin 2): Input Supply Voltage. Bypass VIN with a ≥ 3.3µF low ESR capacitor. GND (Pin 6): Ground. VOUT (Pin 3): 5V Output Voltage (VOUT = 0V in Shutdown). Bypass VOUT with a ≥ 3.3µF low ESR capacitor. SHDN (Pin 7): Active High CMOS Logic-Level Shutdown Input. Drive SHDN low to enable the DC/DC converter. Do not float. C + (Pin 4): Flying Capacitor, Positive Terminal. NC (Pin 8): No Connect. 3 LTC1522 W BLOCK DIAGRAM VIN CIN 10µF SHDN + S2A + S1A + C 1µA CFLY 0.22µF S2B S1B CLOCK 2 CHARGE PUMP COUT 10µF COMP1 CLOCK 1 C– VOUT + CONTROL LOGIC – VREF LTC1522 BD CHARGE PUMP SHOWN IN DISCHARGE CYCLE U W U U APPLICATIONS INFORMATION Operation The LTC1522 uses a switched capacitor charge pump to boost VIN to a regulated 5V ±4% output voltage. Regulation is achieved by sensing the output voltage through an internal resistor divider and enabling the charge pump when the output voltage droops below the lower trip point of COMP1. When the charge pump is enabled, a 2-phase, nonoverlapping clock controls the charge pump switches. Clock 1 closes the S1 switches which enables the flying capacitor to charge up to the VIN voltage. Clock 2 closes the S2 switches that stack CFLY in series with VIN and connect the top plate of CFLY to the output capacitor at VOUT. This sequence of charging and discharging continues at a free-running frequency of 700kHz (typ) until the output has risen to the upper trip point of COMP1 and the charge pump is disabled. When the charge pump is disabled, the LTC1522 draws only 4µA (typ) from VIN which provides high efficiency at low load conditions. In shutdown mode, all circuitry is turned off and the part draws only leakage current from the VIN supply. VOUT is also disconnected from VIN. The SHDN pin is a CMOS input with a threshold of approximately VIN/2; however, the SHDN pin can be driven by logic levels that exceed the VIN voltage. The part enters shutdown mode when a logic 4 high is applied to the SHDN pin. The SHDN pin should not be floated; it must be driven with a logic high or low. Short-Circuit/Thermal Protection During short-circuit conditions, the LTC1522 will draw between 100mA and 200mA from VIN causing a rise in the junction temperature. On-chip thermal shutdown circuitry disables the charge pump once the junction temperature exceeds ≈ 160°C, and reenables the charge pump once the junction temperature falls back to ≈ 145°C. The LTC1522 will cycle in and out of thermal shutdown indefinitely without latchup or damage until the VOUT short is removed. Capacitor Selection For best performance, it is recommended that low ESR (< 0.5Ω) capacitors be used for both CIN and COUT to reduce noise and ripple. The CIN and COUT capacitors should be either ceramic or tantalum and should be 3.3µF or greater (aluminum capacitors are not recommended because of their high ESR). If the input source impedance is very low, CIN may not be needed. Increasing the size of COUT to 10µF or greater will reduce output voltage ripple. LTC1522 U W U U APPLICATIONS INFORMATION A ceramic capacitor is recommended for the flying capacitor with a value in the range of 0.1µF to 0.22µF. Note that a large value flying cap (> 0.22µF) will increase output ripple unless COUT is also increased. For very low load applications, CFLY may be reduced to 0.01µF to 0.047µF. This will reduce output ripple at the expense of efficiency and maximum output current. LTC1522 3 VOUT LTC1522 3 VOUT + 15µF TANTALUM 1µF CERAMIC 3.9Ω + 10µF TANTALUM + VOUT 5V 10µF TANTALUM 1522 F01 Output Ripple Normal LTC1522 operation produces voltage ripple on the VOUT pin. Output voltage ripple is required for the LTC1522 to regulate. Low frequency ripple exists due to the hysteresis in the sense comparator and propagation delays in the charge pump enable/disable circuits. High frequency ripple is also present mainly due to ESR (Equivalent Series Resistance) in the output capacitor. Typical output ripple under maximum load is 50mVP-P with a low ESR 10µF output capacitor. The magnitude of the ripple voltage depends on several factors. High input voltages (VIN > 3.3V) increase the output ripple since more charge is delivered to COUT per clock cycle. A large flying capacitor (> 0.22µF) also increases ripple for the same reason. Large output current load and/ or a small output capacitor (< 10µF) results in higher ripple due to higher output voltage dV/dt. High ESR capacitors (ESR > 0.5Ω) on the output pin cause high frequency voltage spikes on VOUT with every clock cycle. There are several ways to reduce the output voltage ripple. A larger COUT capacitor (22µF or greater) will reduce both the low and high frequency ripple due to the lower COUT charging and discharging dV/dt and the lower ESR typically found with higher value (larger case size) capacitors. A low ESR ceramic output capacitor will minimize the high frequency ripple, but will not reduce the low frequency ripple unless a high capacitance value is chosen. A reasonable compromise is to use a 10µF to 22µF tantalum capacitor in parallel with a 1µF to 3.3µF ceramic capacitor on VOUT to reduce both the low and high frequency ripple. An RC filter may also be used to reduce high frequency voltage spikes (see Figure 1). VOUT 5V Figure 1. Output Ripple Reduction Techniques In low load or high VIN applications, smaller values for CFLY may be used to reduce output ripple. A smaller flying capacitor (0.01µF to 0.047µF) delivers less charge per clock cycle to the output capacitor resulting in lower output ripple. However, the smaller value flying caps also reduce the maximum IOUT capability as well as efficiency. Inrush Currents During normal operation, VIN will experience current transients in the 50mA to 100mA range whenever the charge pump is enabled. During start-up, these inrush currents may approach 250mA. For this reason, it is important to minimize the source resistance between the input supply and the VIN pin. Too much source resistance may result in regulation problems or even prevent start-up. Ultralow Quiescent Current (IQ = 2.1µA) Regulated Supply The LTC1522 contains an internal resistor divider (refer to the Block Diagram) that draws only 1µA (typ) from VOUT. During no-load conditions, the internal load causes a droop rate of only 100mV per second on VOUT with COUT = 10µF. Applying a 2Hz to 100Hz, 95% to 98% duty cycle signal to the SHDN pin ensures that the circuit of Figure 2 comes out of shutdown frequently enough to maintain regulation during no-load or low-load conditions. Since the part spends nearly all of its time in shutdown, the no-load quiescent current (see Figure 3a) is approximately equal to (VOUT)(1µA)/(VIN)(Efficiency). 5 LTC1522 U U W U APPLICATIONS INFORMATION 1 VIN 2.7V TO 5V 2 + 10µF 3 + 10µF 4 NC NC VIN SHDN LTC1522 VOUT GND C+ C– 8 7 FROM MPU SHDN PIN WAVEFORMS: 6 5 LOW IQ MODE (2Hz TO 100Hz, 95% TO 98% DUTY CYCLE) VOUT LOAD ENABLE MODE IOUT ≤ 100µA (IOUT = 100µA TO 20mA) 0.22µF 1522 F02 VOUT 5V ±4% Figure 2. Ultralow Quiescent Current ( 3.3V) and/or low IOUT (< 10µA) conditions, this behavior may cause a net excess of charge to be delivered to the output capacitor if a high frequency signal is used on the SHDN pin (e.g., 50Hz to 100Hz). Under such conditions, VOUT will slowly drift positive and may even go out of regulation. To avoid this potential problem in the low IQ mode, it is necessary to switch the part in and out of shutdown at the minimum allowable frequency (refer to Figure 3b) for a given output load. 6 LTC1522 U U W U APPLICATIONS INFORMATION General Layout Considerations Due to the high switching frequency and high transient currents produced by the LTC1522, careful board layout is a must. A clean board layout using a ground plane and CIN + VIN 1 short connections to all capacitors will improve performance and ensure proper regulation under all conditions (refer to Figure 4). 8 2 7 SHDN LTC1522 VOUT 3 6 4 5 + COUT GND CFLY 1522 F04 Figure 4. Suggested Component Placement for LTC1522 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 4 2 3 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) 0.053 – 0.069 (1.346 – 1.752) 0.008 – 0.010 (0.203 – 0.254) 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 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. 3 4 7 LTC1522 U TYPICAL APPLICATION Programmable 5V/3V SIM Interface Supply for GSM Cellular Phones D1 Q1 3V R1 470k A 1 2 B + TRUTH TABLE A B V CC 0 0 NOT USED 0 1 3V 1 0 5V 1 1 SHUTDOWN 7 NC NC VIN VOUT LTC1522 SHDN GND 10µF 4 C + GSM CONTROLLER C– 8 3 + 6 10µF VCC = 5V OR 3V (SEE TRUTH TABLE) D1 = BAS70-05 Q1 = Si6943DQ 5 0.22µF VCC RST LEVEL SHIFT CLK SIM CARD I/O GND 1522 TA03 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC1144 20mA Switched Capacitor Converter for Up to 20V Inputs Includes Micropower Shutdown (8µA) LTC1262 5V to 12V Regulated Switched Capacitor Converter Up to 30mA at Regulated Output LTC1514/15 Step-Up/Step-Down Switched Capacitor DC/DC Converters VIN 2V to 10V, VOUT is Fixed or Adjustable, IOUT to 50mA LTC1516 Micropower, Regulated 5V Charge Pump DC/DC Converter IOUT = 20mA (VIN ≥ 2V), IOUT = 50mA (VIN ≥ 3V) LTC1517-5 Micropower, Regulated 5V Charge Pump DC/DC Converter LTC1522 Without Shutdown and Packaged in SOT-23 LTC1555/56 SIM Power Supply and Level Translator Step-Up/Step-Down SIM Power Supply and Level Translators LTC660 100mA CMOS Voltage Converter 5V to – 5V Conversion with Low Voltage Loss 8 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 ● (408) 432-1900 FAX: (408) 434-0507● TELEX: 499-3977 ● www.linear-tech.com 1522f LT/TP 0198 4K • PRINTED IN USA  LINEAR TECHNOLOGY CORPORATION 1997