Datasheet LTC4001 (Analog Devices) - 5
| Manufacturer | Analog Devices |
| Description | 2A Synchronous Buck Li-Ion Charger |
| Pages / Page | 20 / 5 — TYPICAL PERFOR A CE CHARACTERISTICS. IDET Threshold vs RIDET for. CHRG … |
| File Format / Size | PDF / 241 Kb |
| Document Language | English |
TYPICAL PERFOR A CE CHARACTERISTICS. IDET Threshold vs RIDET for. CHRG Pin Temperature Fault. Soft-Start (PWM Mode)
Model Line for this Datasheet
Text Version of Document
LTC4001
W U TYPICAL PERFOR A CE CHARACTERISTICS IDET Threshold vs RIDET for CHRG Pin Temperature Fault Soft-Start (PWM Mode) RPROG = 549
Ω
Behavior (Detail)
400 INPUT 350 CURRENT (IIN) 0.5A/DIV 300 0 INDUCTOR 250 CHRG CURRENT (IL) 1V/DIV 0.5A/DIV 0 200 SOFT-START VOLTAGE (V IDET (mA) SS) 150 1V/DIV 0 EN PIN (VEN) 100 5V/DIV 0 V 2ms/DIV 4001 G09 BAT = 3.5V TIME (20µs/DIV) 4001 G11 50 VIN = 5V 0300 400 500 600 700 800 900 100011001200 RIDET (Ω) 4001 G10
U U U PI FU CTIO S BAT (Pin 1):
Battery Charger Output Terminal. Connect a internal N-channel MOSFET. When the charge current 10µF ceramic chip capacitor between BAT and PGND to drops below the IDET threshold (set by the RIDET program- keep the ripple voltage small. ming resistor) for more than 5milliseconds, the N-channel MOSFET turns off and a 30µA current source is connected
SENSE (Pin 2):
Internal Sense Resistor. Connect to exter- from CHRG to ground. (This signal is latched and is reset nal inductor. by initiating a new charge cycle.) When the timer runs out
PGND (Pin 3):
Power Ground. or the input supply is removed, the current source will be
GNDSENS (Pin 4):
Ground Sense. Connect this pin to the disconnected and the CHRG pin is forced to a high imped- negative battery terminal. GNDSENS provides a Kelvin ance state. A temperature fault causes this pin to blink. connection for PGND and must be connected to PGND
PVIN (Pin 8):
Positive Supply Voltage Input. This pin schematically. connects to the power devices inside the chip. VIN ranges
SW (Pin 5):
Switch Node Connection. This pin connects to from 4V to 5.5V for normal operation. Operation down to the drains of the internal main and synchronous power the undervoltage lockout threshold is allowed with current MOSFET switches. Connect to external inductor. limited wall adapters. Decouple with a 10µF or larger surface mounted ceramic capacitor.
EN (Pin 6):
Enable Input Pin. Pulling the EN pin high places the LTC4001 into a low power state where the BAT drain
VINSENSE (Pin 9):
Positive Supply Sense Input. This pin current drops to less than 3µA and the supply current is connects to the inputs of all input comparators (UVL, VIN reduced to less than 50µA. For normal operation, pull the to VBAT). It also supplies power to the controller portion of pin low. this chip. When the BATSENS pin rises to within 30mV of VINSENSE, the LTC4001 enters sleep mode, dropping IIN to
CHRG (Pin 7):
Open-Drain Charge Status Output. When 50µA. Tie this pin directly to the terminal of the PVIN the battery is being charged, CHRG is pulled low by an decoupling capacitor. 4001f 5
W U TYPICAL PERFOR A CE CHARACTERISTICS IDET Threshold vs RIDET for CHRG Pin Temperature Fault Soft-Start (PWM Mode) RPROG = 549
Ω
Behavior (Detail)
400 INPUT 350 CURRENT (IIN) 0.5A/DIV 300 0 INDUCTOR 250 CHRG CURRENT (IL) 1V/DIV 0.5A/DIV 0 200 SOFT-START VOLTAGE (V IDET (mA) SS) 150 1V/DIV 0 EN PIN (VEN) 100 5V/DIV 0 V 2ms/DIV 4001 G09 BAT = 3.5V TIME (20µs/DIV) 4001 G11 50 VIN = 5V 0300 400 500 600 700 800 900 100011001200 RIDET (Ω) 4001 G10
U U U PI FU CTIO S BAT (Pin 1):
Battery Charger Output Terminal. Connect a internal N-channel MOSFET. When the charge current 10µF ceramic chip capacitor between BAT and PGND to drops below the IDET threshold (set by the RIDET program- keep the ripple voltage small. ming resistor) for more than 5milliseconds, the N-channel MOSFET turns off and a 30µA current source is connected
SENSE (Pin 2):
Internal Sense Resistor. Connect to exter- from CHRG to ground. (This signal is latched and is reset nal inductor. by initiating a new charge cycle.) When the timer runs out
PGND (Pin 3):
Power Ground. or the input supply is removed, the current source will be
GNDSENS (Pin 4):
Ground Sense. Connect this pin to the disconnected and the CHRG pin is forced to a high imped- negative battery terminal. GNDSENS provides a Kelvin ance state. A temperature fault causes this pin to blink. connection for PGND and must be connected to PGND
PVIN (Pin 8):
Positive Supply Voltage Input. This pin schematically. connects to the power devices inside the chip. VIN ranges
SW (Pin 5):
Switch Node Connection. This pin connects to from 4V to 5.5V for normal operation. Operation down to the drains of the internal main and synchronous power the undervoltage lockout threshold is allowed with current MOSFET switches. Connect to external inductor. limited wall adapters. Decouple with a 10µF or larger surface mounted ceramic capacitor.
EN (Pin 6):
Enable Input Pin. Pulling the EN pin high places the LTC4001 into a low power state where the BAT drain
VINSENSE (Pin 9):
Positive Supply Sense Input. This pin current drops to less than 3µA and the supply current is connects to the inputs of all input comparators (UVL, VIN reduced to less than 50µA. For normal operation, pull the to VBAT). It also supplies power to the controller portion of pin low. this chip. When the BATSENS pin rises to within 30mV of VINSENSE, the LTC4001 enters sleep mode, dropping IIN to
CHRG (Pin 7):
Open-Drain Charge Status Output. When 50µA. Tie this pin directly to the terminal of the PVIN the battery is being charged, CHRG is pulled low by an decoupling capacitor. 4001f 5
