LTC1514-3.3 LINER
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LTC1514-3.3/LTC1514-5 Step-Up/Step-Down Switched Capacitor DC/DC Converters with Low-Battery Comparator n 3.3V or 5V Output Voltages n 2V to 10V Input Voltage Range n Up to 50mA Output Current n Only Three External Capacitors Required n Soft Start Limits Inrush Current at Turn-On n Low Operating Current: 60µA n Low Shutdown Current: 10µA n Shutdown Disconnects Load from VIN n Short-Circuit and Overtemperature Protected n 650kHz Switching Frequency n Low-Battery Comparator Active in Shutdown n Available in SO-8 Package FEATURES DESCRIPTIONU The LTC 1514-3.3/LTC1514-5 are micropower switched capacitor DC/DC converters that produce a regulated output voltage by either stepping up or stepping down the input voltage. Output voltage is fixed at either 3.3V (LTC1514-3.3) or 5V (LTC1514-5) by an internal resistor divider. A unique architecture allows the parts to accommodate a wide input voltage range (2V to 10V) while maintaining ±4% regulation. Additional circuitry prevents excessive inrush current and output voltage ripple when large VIN to VOUT differentials are present. An internal uncommitted comparator is kept active in shutdown. The comparator has an open-drain output for flexible interfacing. The parts are short-circuit and overtemperature pro- tected. Battery life is maximized by very low operating currents (ICC = 60µA typ, 10µA in shutdown). Both parts are available in an SO-8 package. , LTC and LT are registered trademarks of Linear Technology Corporation. APPLICATIONSU n Battery-Operated Equipment n Smart Card Readers n Local Power Supplies n Handheld Instruments n Battery Backup Supplies INPUT VOLTAGE (V) OUTPUT VOLTAGE (V) LT1514 • TA02 4 6 83 5 7 9 5.2 5.1 5.0 4.9 4.8 IOUT = 10mA TYPICAL APPLICATIONU SHDN LBO LBI GND V OUT VIN C1+ C1– LTC1514-5 100k VOUT = 5V IOUT = 50mA 0.22µF 10µF 10µF VIN 4-CELL NiCd 1.33M 499k ON OFF LOW BAT 1514 TA01 5V Step-Up/Step-Down Power Supply with Low-Battery Detect LTC1514-5 Output Voltage vs Input Voltage
LTC1514-3.3/LTC1514-5 ABSOLUTE MAXIMUM RATINGSW WW U PACKAGE/ORDER INFORMATIONW UU ORDER PART NUMBER S8 PART MARKING The l denotes specifications which apply over the full operating temperature range. Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. LTC1514CS8-3.3 LTC1514CS8-5 LTC1514IS8-3.3 LTC1514IS8-5 15143 15145 1514I3 1514I5 Consult factory for Military grade parts. PARAMETER CONDITIONS MIN TYP MAX UNITS VIN Operating Voltage LTC1514-3.3 l 2.0 8 V LTC1514-5 l 2.7 10 V VOUT (LTC1514-3.3) 2V ≤ VIN ≤ 8V, IOUT ≤ 15mA l 3.17 3.3 3.43 V 3V ≤ VIN ≤ 8V, IOUT ≤ 50mA l 3.17 3.3 3.43 V VOUT (LTC1514-5) 2.7V ≤ VIN ≤ 10V, IOUT ≤ 15mA l 4.8 5 5.2 V 3.3V ≤ VIN ≤ 10V, IOUT ≤ 50mA l 4.8 5 5.2 V VIN Operating Current V IN ≤ 5V, IOUT = 0, SHDN = 3V l 60 100 µA VIN > 5V, IOUT = 0, SHDN = 3V l 75 120 µA VIN Shutdown Current SHDN = 0V, V IN ≤ 5V l 10 20 µA SHDN = 0V, VIN > 5V 35 µA Output Ripple Full Load (Note 2) 100 mV P-P Switching Frequency l 500 650 800 kHz LBI Trip Point LBI Ramping Negative l 1.110 1.145 1.180 V LBI Trip Point Hysteresis 1% LBI Input Current LBI = 1.145V l –50 50 nA LBO VOL ISINK = 100µA, VIN = 3V l 0.025 0.4 V LBO Leakage Current V LBO = 5V, LBI = VIN l –1 1 µA SHDN Input Threshold V IL l 0.4 1 V VIH l 1 1.6 V SHDN Input Current SHDN = V IN l –1 1 µA SHDN = 0V l –1 1 µA IOUT Short-Circuit Current V OUT = 0V l 12 40 mA tON Soft Start Turn-On Time 4 ms VIN = 2V to 10V, SHDN = 3V, C1 = 0.22µF, CIN = COUT = 10µF, unless otherwise noted (Note 2).
ELECTRICAL CHARACTERISTICS
C1– TJMAX = 125°C, θJA = 110°C/ W Note 2: For VIN ≥ 8V, COUT = 22µF. (Note 1) V Operating Temperature Range
LTC1514-3.3/LTC1514-5 TYPICAL PERFORMANCE CHARACTERISTICS UW LTC1514-3.3 Efficiency vs Output Current INPUT VOLTAGE (V) OUTPUT VOLTAGE RIPPLE (mVP-P) 250 200 150 100
1514 G03
VOUT = 3.3V IOUT = 10mA TA = 25°C COUT = 10µF COUT = 22µF COUT = 47µF LTC1514-3.3 Output Voltage Ripple vs Input Voltage OUTPUT CURRENT (mA) EFFICIENCY (%) 0.01 1 10
1514 G02
0.1 100 100 VOUT = 5V TA = 25°C VIN = 8V VIN = 3.3V VIN = 6VVIN = 2.7V LTC1514-5 Efficiency vs Output Current OUTPUT CURRENT (mA) EFFICIENCY (%) 0.01 1 10
1514 G01
0.1 100 100 VOUT = 3.3V TA = 25°C VIN = 2V VIN = 4.4V VIN = 2.7V VIN = 6V LTC1514-5 Output Voltage Ripple vs Input Voltage LTC1514-5 Operating Current vs Input Voltage LTC1514-3.3 Output Voltage vs Input Voltage INPUT VOLTAGE (V) OUTPUT VOLTAGE RIPPLE (mVP-P) 250 200 150 100
1514 G04
VOUT = 5V IOUT = 10mA TA = 25°C COUT = 10µF COUT = 47µF COUT = 22µF INPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 3.45 3.40 3.35 3.30 3.25 3.20
1514 G05
VOUT = 3.3V COUT = 10µF TA = 25°C INPUT VOLTAGE (V) OPERATING CURRENT (µA) 120 100
1514 G06
85°C –40°C 25°C VOUT = 5V IOUT = 0mA LTC1514-5 Efficiency vs Input Voltage INPUT VOLTAGE (V) EFFICIENCY (%) 100
1514 G07
VOUT = 3.3V IOUT = 10mA TA = 25°C INPUT VOLTAGE (V) EFFICIENCY (%) 100
1514 G08
VOUT = 5V IOUT = 10mA TA = 25°C LTC1514-3.3 Efficiency vs Input Voltage LTC1514-X Shutdown Supply Current vs Input Voltage INPUT VOLTAGE (V) SHUTDOWN SUPPLY CURRENT (µA)
1514 G09
85°C –40°C SHDN = 0V 25°C
LTC1514-3.3/LTC1514-5 TYPICAL PERFORMANCE CHARACTERISTICS UW LTC1514-5 Step-Up Mode Load Transient Response LTC1514-5 Step-Down Mode Load Transient Response 50mA 0mA VOUT AC COUPLED 100mV/DIV IOUT 50mA/DIV VIN = 8V, VOUT = 5V, COUT = 10µF, TA = 25°C
1514 G10
VIN = 3.3V, VOUT = 5V, COUT = 10µF, TA = 25°C
1514 G11
1.145V VREF STEP-UP/STEP-DOWN CHARGE PUMP VIN VOUT LBI 1514 BD C1– C1+ SHDN LBO GND SHDN (Pin 1): Shutdown Input. A logic low on the SHDN pin puts the part into shutdown mode. A logic high (VSHDN ≥ 1.6V) enables the charge pump regulator. At high VIN voltages, the SHDN pin may still be controlled with 3V logic without causing a large rise in VIN quiescent current. The SHDN pin may not float; connect to V IN if unused. PIN FUNCTIONSUU U LBO (Pin 2): Open-Drain, Low-Battery Comparator Out- put. This pin will pull low whenever the voltage on the LBI pin is less than the internal reference voltage (1.145V typ). LBI (Pin 3): Low-Battery Comparator Input. The voltage on this pin is compared to the internal reference voltage (1.145V). The LBO output will sink current when the voltage on the LBI pin is less than 1.145V typ. The low-
LTC1514-3.3/LTC1514-5 PIN FUNCTIONSUU U battery comparator and 1.145V reference are kept alive in shutdown. GND (Pin 4): Ground. Should be tied to a ground plane for best performance. C1– (Pin 5): Charge Pump Flying Capacitor, Negative Terminal. C1+ (Pin 6): Charge Pump Flying Capacitor, Positive Terminal. VIN (Pin 7): Charge Pump Input Voltage. May be between 2V and 8V (LTC1514-3.3) or between 2.7V and 10V (LTC1514-5). VIN should be bypassed with a ≥ 10µF low ESR capacitor as close as possible to the pin for best performance. VOUT (Pin 8): Regulated Output Voltage. The output volt- age is internally set to either 3.3V (LTC1514-3.3) or to 5V (LTC1514-5) using an internal resistor divider. VOUT should be bypassed with a ≥ 10µF low ESR capacitor as close as possible to the pin for best performance. APPLICATIONS INFORMATIONWU UU Regulator Operation The regulator section of the LTC1514-3.3/LTC1514-5 consists of a charge pump, reference, comparator and some logic. The divided down output voltage is com- pared to the internal reference voltage. When the divided output drops below the reference voltage, the charge pump is enabled, which boosts the output back into regulation. Hysteresis in the comparator forces the regu- lator to burst on and off and causes approximately 100mV of peak-to-peak ripple to appear at the output. By enabling the charge pump only when needed, the LTC1514-3.3 and LTC1514-5 are able to achieve high efficiencies with low output load currents. Each part’s charge pump has a unique architecture that allows the input voltage to be either stepped up or stepped down to produce a regulated output. Internal circuitry senses the V IN to VOUT differential voltage and controls the charge pump operating mode. In addition, the effective output impedance of the charge pump is internally adjusted to prevent large inrush currents and allow for a wide input voltage range. When the input voltage is lower than the output voltage, the charge pump operates as a step-up voltage doubler. When the input voltage is greater than the output, the charge pump operates as a step-down gated switch. Capacitor Selection For best performance, low ESR capacitors are recom- mended for both C IN and COUT to reduce noise and ripple. The CIN and COUT capacitors should be either ceramic or tantalum and should be 10 µF or greater. If the input source impedance is very low (<0.5Ω ), CIN may not be needed. Increasing the size of COUT to 22µF or greater will reduce output voltage ripple—particularly with high V IN voltages (8V or greater). A ceramic capacitor is recom- mended for the flying capacitor C1 with a value of 0.1µF or 0.22µF. Smaller value flying capacitors may be used in low output current applications. Output Ripple Normal LTC1514-3.3/LTC1514-5 operation produces voltage ripple on the V OUT pin. Output voltage ripple is required for the parts 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 from the ESR (equivalent series resistance) in the output capacitor. Typical output ripple (V IN < 8V) under maxi- mum load is 100mV peak-to-peak with a low ESR (< 0.5Ω ) 10µF output capacitor. For applications requiring VIN to exceed 8V, a 22 µF or larger C OUT capacitor is recom- mended to maintain max ripple in the 100mV range. The magnitude of the ripple voltage depends on several factors. High input voltages increase the output ripple since more charge is delivered to C OUT per charging cycle. A large C1 flying capacitor (>0.22 µF) also increases ripple in step-up mode 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
to reduce high frequency voltage spikes (see Figure 1). enabled and helps to reduce both input and output ripple. current, even at high input supply voltages.
1514 F01
Figure 1. Output Ripple Reduction Techniques Figure 2. Programming the Low-Battery Comparator Trip Voltage
1514 F02
LTC1514-3.3/LTC1514-5 APPLICATIONS INFORMATIONWU UU resistor divider (see Figure 2). Since the low-battery comparator is kept alive in shutdown, it may be used to protect batteries against deep discharge by shutting down the power supply when the battery voltage gets too low. The open-drain comparator output allows for flex- ible interfacing between the LBO output and external logic. LBO pull-up resistors in the 50k to 1M range are recommended. TYPICAL APPLICATIONS N U 3.3V Step-Up/Step-Down Supply with Power Good Output SHDN LBO LBI GND V OUT VIN C1+ C1– LTC1514-3.3 VOUT = 3.3V – 4% IOUT = 15mA, VIN > 2V IOUT = 50mA, VIN > 3VVIN 2V TO 8V 0.22µF499k 10µF 10µF 806k 1% 100k
1514 TA05
Low Power Battery Backup Supply with Autoswitchover and No Reverse Current SHDN LBO LBI GND V OUT VIN C1+ C1– LTC1514-5 5V BACKUP SUPPLY IOUT = 15mA 0.1µF 499k MAIN 5V SUPPLY 10µF 10µF 3-CELL NiCd BATTERY TRICKLE CHARGE AND LTC1514 IDD 499k 1.5M 499k
1514 TA03
4.6V VTRIP TP0610T BACKED-UP CIRCUITRY BAT54 SHDN LBO LBI GND V OUT VIN C1+ C1– LTC1514-5 MBR0520L 0.22µF CHARGE PATH 499k 3-CELL NiCd BATTERY 499k WALL ADAPTER INPUT
1514 TA06
ON OFF 10µF 22µF Battery/External Power Autoswitch Regulator 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 represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
LTC1514-3.3/LTC1514-5 151435f LT/TP 0298 4K • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 1 997 TYPICAL APPLICATIONS N U Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 l (408) 432-1900 FAX: (408) 434-0507 l TELEX: 499-3977 l www.linear-tech.com PART NUMBER DESCRIPTION COMMENTS LTC1515 Series Step-Up/Step-Down Switched Capacitor DC/DC Converters with Reset V IN 2V to 10V, 3.3V, 5V and ADJ Versions, IOUT to 50mA LTC1516 Micropower, Regulated 5V Charge Pump DC/DC Converter I OUT = 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 LTC1522 Micropower, Regulated 5V Charge Pump DC/DC Converter Available in 8-Pin MSOP, 6 µA Quiescent Current, IOUT = 20mA LTC1555/LTC1556 SIM Power Supply and Level Translators Step-Up/Step-Down SIM Power Supply and Level Translators LTC660 100mA CMOS Voltage Converter 5V to –5V Conversion with Low Voltage Loss RELATED PARTS 1 2 3 4 0.150 – 0.157** (3.810 – 3.988) 8 7 6 5 0.189 – 0.197* (4.801 – 5.004) 0.228 – 0.244 0.406 – 1.270 0.010 – 0.020 0°– 8° TYP 0.008 – 0.010 (0.203 – 0.254) SO8 0996 0.053 – 0.069 (1.346 – 1.752) 0.014 – 0.019 (0.355 – 0.483) 0.004 – 0.010 (0.101 – 0.254) 0.050 (1.270) TYP 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 Low Power Dual Output Supply (Maximum Combined IOUT = 50mA)
1514 TA04
3.3V –4% VOUT 5V –4% VIN 2.7V TO 10V 747k 220k 10Ω 750k 402k 2.2nF Q1: TP0610T Q2: MMBT3906LT1 5 0.22µF 10µF 22µF1 0 µF + + + SHDN LBO LBI GND V OUT VIN C1+ C1– LTC1514-5 Step-Up/Step-Down Power Supply with Input Autoswitching 8-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) Dimensions in inches (millimeters) unless otherwise noted.PACKAGE DESCRIPTIONU SHDN LBI LBO V OUT C1+ C1– LTC1514-5 0.22µF 10k MMBT 3904LT1 MMBT 3904LT1 2N7002 22µF 10V 4 × AAA ALKALINE CELLS 10k 470k CENTRAL SEMI CMPD6263C
1514 TA07
10µF 25V EXT_PWR_GOOD VOUT 50mA V IN GND ON OFF 100k 2.4k Si6943DQ Si6943DQSi6943DQ MMBD 914LT1 MMBZ 5235BLT1 (6.8V) +6VDC WALL ADAPTER