ADP3810

Features:

Programmable Charge Current
High Precision Battery Voltage Limit
Precision 2.000 V Reference
Low Voltage Drop Current Sense: 300 mV Full Scale
Full Operation in Shorted and Open Battery Conditions
Drives Diode-Side of Optocoupler
Wide Operating Supply Range: 2.7 V to 16 V
Undervoltage Lockout
SO-8 Package
ADP3810
    Internal Precision Voltage Divider for Battery Sense
    Four Final Battery Voltage Options Available: 4.2 V,
    8.4 V, 12.6 V, 16.8 V
ADP3811
    Adjustable Final Battery Voltage


Application

Battery Charger Controller for:
    LiIon Batteries (ADP3810)
    NiCad, NiMH Batteries (ADP3811)


Pinout

PIN DESCRIPTION
Mnemonic	Function
VSENSE	Battery Voltage Sense Input.
VCS	Current Sense Input.
VREF	Reference Output. Nominally 2.0 V.
COMP	External Compensation Pin.
OUT	Optocoupler Current Output Drive.
VCTRL	DC Control Input to Set Current Limit, 0 V to 1.2 V.
VCC	Positive Supply.
GND	Ground Pin.

Specifications

Supply Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.4 V to 18 V
V_CTRL, VCS Input Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.4 V to V_CC
V_SENSE Input Range (ADP3811) . . . . . . . . . . . . . . . . . . . . . . . . . . . .  0.4 V to V_CC
V_SENSE Input Range (ADP3810) . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.4 V to 20 V
Maximum Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500 mW
Operating Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . 40°C to +85°C
Storage Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65°C to 150°C
Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . . +300°C


Description

The ADP3810 and ADP3811 combine a programmable current limit with a battery voltage limit to provide a constant current, constant voltage battery charger controller. In secondary side, off-line applications, the output directly drives the diode side of an optocoupler to give isolated feedback control of a primary side PWM. The circuitry includes two gain (g_m) stages, a precision 2.0 V reference, a control input buffer, an Undervoltage Lock Out (UVLO) comparator, an output buffer and an overvoltage comparator.

The ADP3810 and ADP3811 current limit amplifier senses the voltage drop across an external sense resistor to control the average current for charging a battery. The voltage drop can be adjusted from 25 mV to 300 mV, giving a charging current limit from 100 mA to 1.2 amps with a 0.25 sense resistor. An external dc voltage on the VCTRL input sets the voltage drop. Because this input is high impedance, a filtered PWM output can be used to set the voltage.

As the battery voltage approaches ADP3810 and ADP3811's voltage limit, the voltage sense amplifier takes over to maintain a constant battery voltage. The two amplifiers essentially operate in an "OR" fashion. Either the current is limited, or the voltage is limited.

The ADP3810 and ADP3811 have internal thin-film resistors that are trimmed to provide a precise final voltage for LiIon batteries. Four voltage options are available, corresponding to 1-4 LiIon cells as
follows: 4.2 V, 8.4 V, 12.6 V and 16.8 V.

The ADP3810 and ADP3811 omit these resistors allowing any battery voltage to be programmed with external resistors.