Datasheet LTC4007-1 (Analog Devices) - 7

LTC4007-1
pin FuncTions PROG (Pin 9):
Current Programming/Monitoring Input/
CLP (Pin 15):
Positive input to the supply current limiting Output. An external resistor to GND programs the peak amplifier, CL1. The threshold is set at 100mV above the charging current in conjunction with the current sensing voltage at the CLN pin. When used to limit supply current, resistor. The voltage at this pin provides a linear indication of a filter is needed to filter out the switching noise. If no charging current. Peak current is equivalent to 1.19V. Zero current limit function is desired, connect this pin to CLN. current is approximately 0.3V. A capacitor from PROG to
CLN (Pin 16):
Negative Reference for the Input Current ground is required to filter higher frequency components. Limit Amplifier, CL1. This pin also serves as the power The maximum resistance to ground is 100k. Values higher supply for the IC. A 10µF to 22µF bypass capacitor should than 100k can cause the charger to shut down. be connected as close as possible to this pin.
ICL (Pin 10):
Input Current Limit Indicator. Active low digital
TGATE (Pin 17):
Drives the top external P-channel MOSFET output. Internal 10µA pull-up to 3.5V. Pulled low if the of the battery charger buck converter. charger current is being reduced by the input current limit- ing function. The pin is capable of sinking at least 100µA.
PGND (Pin 18):
High Current Ground Return for the If VLOGIC is greater than 3.3V, add an external pull-up. BGATE Driver.
CSP (Pin 11):
Current Amplifier CA1 Input. The CSP and
NC (Pin 19):
No Connect. BAT pins measure the voltage across the sense resistor, BGATE (Pin 20): Drives the bottom external N-channel RSENSE, to provide the instantaneous current signals re- MOSFET of the battery charger buck converter. quired for both peak and average current mode operation.
INFET (Pin 21):
Drives the Gate of the External Input PFET.
BAT (Pin 12):
Battery Sense Input and the Negative Refer- ence for the Current Sense Resistor. A precision internal
SHDN (Pin 22):
Charger is shut down and timer is reset resistor divider sets the final float potential on this pin. when this pin is HIGH. Internal 10µA pull-up to 3.5V. This The resistor divider is disconnected during shutdown. pin can also be used to reset the charger by applying a positive pulse that is a minimum of 0.1µs long.
CHEM (Pin 13):
Select 4.1V or 4.2V cell chemistry by con- necting the pin to GND or open, respectively. Internal 14µA
DCIN (Pin 23):
External DC Power Source Input. Bypass pull-up to 5.3V. Can also be driven with open-collector/ this pin with at least 0.01µF. See Applications Information. drain logic levels.
CHG (Pin 24):
Charge Status Output. When the battery is
FLAG (Pin 14):
Active low open-drain output that indicates being charged, the CHG pin is pulled low by an internal when charging current has declined to 10% of maximum N-channel MOSFET. Internal 10µA pull-up to 3.5V. If VLOGIC programmed current. A pull-up resistor is required if this is greater than 3.3V, add an external pull-up. The timer function is used. The pin is capable of sinking at least 100µA. function can be defeated by forcing this pin below 1V (or connecting it to GND).
Exposed Pad (Pin 25):
The exposed pad, GND and PGND should be connected together with a low ohmic connection. 40071fa For more information www.linear.com/LTC4007-1 7 Document Outline Description Typical Application Absolute Maximum Ratings Typical Performance Characteristics Pin Functions Block Diagram Operation Typical Application Related Parts