LTC4425 Linear Technology, LTC4425 Datasheet
LTC4425
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LTC4425 Summary of contents
Page 1
... LDO mode at a constant charge current current profi limit the inrush current until the V differential is less than 250mV. In addition the LTC4425 can be set to clamp the output voltage to 4.9V or 5.4V. Charge current (V connecting a resistor between PROG and GND. The voltage on the PROG pin represents the current fl ...
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... LTC4425EDD#PBF LTC4425EDD#TRPBF LTC4425IDD#PBF LTC4425IDD#TRPBF LTC4425EMSE#PBF LTC4425EMSE#TRPBF LTC4425IMSE#PBF LTC4425IMSE#TRPBF Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi label on the shipping container. For more information on lead free part marking, go to: For more information on tape and reel specifi cations, go to: 2 Storage Temperature Range ..................– ...
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... Hi SEL SEL SEL If Either Capacitor Reaches Clamp Voltage i.e. V < V OUT 1k, (V – > V PROG OUT MID CLAMP R = 1k, V > V PROG MID CLAMP LTC4425 www.DataSheet4U.com MIN TYP MAX UNITS l 2.7 5 μA 3 μA 3 μ mΩ l 1.18 1.2 1.22 V 100 nA ...
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... Specifi cations over the –40°C to 125°C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LTC4425I (I grade) is guaranteed over the full –40°C to 125°C operating junction temperature range. The junction temperature, T from the ambient temperature, T the formula: • ...
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... FB PIN SHORTED TO GND AMBIENT TEMP 24°C 2000 1500 1000 500 THERMAL REGULATION ON-CHIP POWER DISSIPATION ~4W CASE TEMP ~100° 0.5 1 1.5 2 2.5 3 3.5 4 4.5 OUTPUT VOLTAGE (V) 4425 G08 LTC4425 www.DataSheet4U.com Charger FET On-Resistance vs Supply 80 70 90°C 60 25°C 50 –45° 2.7 3 3.3 3.6 3.9 4.2 4.5 4 ...
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... LTC4425 TYPICAL PERFORMANCE CHARACTERISTICS Logic Inputs (EN and SEL) Threshold Voltage vs Temperature 0 3.8V IN 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 –45 –25 – TEMPERATURE (°C) 4425 G10 Charge Current vs Voltage Across Top Capacitor (V – OUT MID 3500 3000 PROG PIN GROUNDED 2500 2000 1500 1000 RPROG = 3.8V ...
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... DC source like a Li-Ion/Polymer battery or a USB port GND (Exposed Pad Pin 13): GND. The Exposed Pad should be connected to a continuous ground plane on the second layer of the printed circuit board by several vias directly under the part to achieve optimum thermal conduction. LTC4425 www.DataSheet4U.com is less than a value IN has OUT in IN and PFI_RET pin ...
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... V OUT – – 15mV IDEAL DIODE CONTROLLER CONSTANT-VOLTAGE/ CONSTANT-CURRENT/ CONSTANT-TEMPERATURE CHARGER CIRCUITRY + 1.11V OSCILLATOR – PGOOD COMPARATOR 200ms TIMER GND Figure 1. LTC4425 Block Diagram www.DataSheet4U.com V OUT PSHUNT V MID VOLTAGE CLAMP R CIRCUITRY LBA NSHUNT V OUT/2 LEAKAGE R BALANCER V SEL 2.7V 2.45V PROG FB 4425 BD ...
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... Charge Current Profi Normal Mode The LTC4425 is in charge current profi le mode when the FB pin is shorted to the input voltage V of operation, the constant-voltage amplifi internally ...
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... The internal balancer eliminates the need for external balancing resistors. Short-Circuit Current Limit In the event the PROG pin gets shorted to GND, the LTC4425 limits the PROG pin current to approximately 3mA which, in turn, limits the maximum charge current to about 3A. ...
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... However, the internal leakage balancer is turned off under this condition. Shutdown Mode The LTC4425 can be shut down by pulling the EN pin low. falls below In shutdown mode, very minimal circuitry is alive and OUT the part draws less than 2μ ...
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... LTC4425 APPLICATIONS INFORMATION Programming the Output Voltage In LDO mode, the LTC4425 output voltage can be pro- grammed for any voltage between 2.7V and V a resistor divider from V pin to GND via the FB pin OUT such that • OUT FB FB1 FB2 where V is 1.2V. See Figure 3. ...
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... CHRG • θ V – OUT JA For example, if the LTC4425 is used in LDO mode to charge a completely discharged supercap stack (V room temperature of 25°C from a 5V source, the charge current, at fi rst, will be limited to approximately: ° ° 105 C – CHRG • ...
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... AA 1.5M V MID PFI LTC4425 1.2M FB PFI_RET 470k SEL PFO μC EN PROG 500Ω 4425 TA04 Li-Ion High Peak Power Battery Buffer V V OUT IN Li-Ion V MID SEL LTC4425 1.5M EN PFO FB PFI PROG 1.2M 500Ω PFI-RET 4425 TA04a www.DataSheet4U.com TO LOAD 1F 2.1M 1F 1.2M TO LOAD 1F 2.1M 1F 1.2M CURRENT MONITOR ...
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... SW1 ≈ LTC3533 0.55F OFF ON RUN/SS HS203F R T 10μ SGND 33.2k 2k LTC4425 www.DataSheet4U.com INSTANT- OUT IN C3 LTC4425 10μF R7 0805 1.5M V MID PFI 1.2M FB PFI_RET PFO PROG μC SEL GND 4425 TA05 SW2 V 3.3V PV OUT 1.5A 340k 6.49k ...
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... SEL EN www.DataSheet4U.com 3.3V HIGH PEAK OUT IN POWER LOAD C SP1 LTC4425 1F V MID C SP2 PFI 1F 2.1M FB PFI_RET PFO PROG SEL R6 1. GND 4425 TA06 5V V OUT HIGH-PEAK POWER, C SP1 OR BACKUP SUPPLY 1F V MID C SP2 1F LTC4425 PROG R6 2k GND 4425 TA07 4425p ...
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... TYPICAL APPLICATIONS μC Redundant High Peak Power Battery Supplies USB OUT FB V 1.5M MID PFI LTC4425 1.2M PFI_RET SEL EN PROG PFO USB POWER OUT 1. MID PFI LTC4425 1.2M PFI_RET PFO SEL PROG EN 4425 TA08 LTC4425 www.DataSheet4U.com TO LOAD 1F 1F BAT POWER OK 4425p 17 ...
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... LTC4425 PACKAGE DESCRIPTION 3.50 ±0.05 2.10 ±0.05 0.25 ± 0.05 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED PIN 1 TOP MARK (SEE NOTE 6) 0.200 REF NOTE: 1. DRAWING IS NOT A JEDEC PACKAGE OUTLINE 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH ...
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... MAX SEATING PLANE 0.22 – 0.38 (.009 – .015) 0.650 TYP (.0256) BSC LTC4425 www.DataSheet4U.com 6 0.35 REF 0.12 REF DETAIL “B” CORNER TAIL IS PART OF THE LEADFRAME FEATURE. DETAIL “B” FOR REFERENCE ONLY 7 NO MEASUREMENT PURPOSE 0.406 ± ...
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... Supercapacitors in Series to a Fixed Output Voltage (4.8V/5/3V Selectable) www.linear.com ● www.DataSheet4U.com 11 5V OUT SP1 1. MID C 9 SP2 PFI 1F R8 LTC4425 1. PFI_RET PROG 8 PFO R6 500Ω 4 SEL μ GND 4425 TA09 3.3V 750k 10μF 240k 1.8V 300k 4.7μF 240k 1.2V 150k 4.7μ ...