© 2008 Semtech Corporation

SC802/SC802A

12

Applications Information (continued)

Status

Indicator

ON

(active

low)

OFF

(inactive

high)

Blinking

CPB

UVLO

< V

VCC

<

OVP

Power Not

Good

X

CHRGB

I

OUT

> I

TERM

I

OUT

< I

TERM

(1)

Pre-charge

or NTC fault

(1) Output remains on when timer is enabled and t < T

QCOMP

.

The CPB output can be used as a VCC–valid detector.

When V

VCC

is between the UVLO and OVP thresholds the

CPB output is low. In the SC802, the CPB output reflects

the voltage of the VCC input regardless of the voltage

V

EN_NTC

. In the SC802A, the CPB output becomes inactive

(high) when the charger is disabled, regardless of V

VCC

.

The CHRGB output signifies the charging status. When

I

VOUT

> I

TERM

, CHRGB is driven low. CHRGB is high when

I

VOUT

< I

TERM

. The CHRGB output is latched during the charge

cycle when the output current is less than I

TERM

. This latch

is reset when the battery enters a re-charge cycle, or if

BIPB, EN_NTC, or VCC are toggled. The CHRGB indicator

operates the same way in both charging and LDO

modes.

The five fault conditions detected by the SC802/A are

input under-voltage, input over-voltage, NTC temperature

fault, maximum die over-temperature (OT) fault, and pre-

charge timeout. The status indicator states for these fault

conditions are shown in the following table.

Fault

CPB

CHRB

VCC UVLO or

VCC OVP

OFF

OFF

NTC Fault

ON

Blinking

Pre-Charge Time-out

ON

Blinking

TJ > 150ºC

OFF

OFF

Configuring the Output Voltage to the Battery

V

The battery voltage is set by the VPRGM pin in fixed mode

and externally in the adjust mode. If VPRGM is logic high

the output voltage is set to 4.2V. If this pin is logic low the

output voltage will be set to 4.1V. For a value other than

4.1V or 4.2V a resistor divider is required.

V

V

CV

Adjust Mode permits configuring the SC802/A for V

CV

other than 4.1V or 4.2V. In V

CV

Adjust Mode the CV regula-

tion voltage is set by an external resistor divider. The

SC802/A Adjust Mode schematic is shown in Figure 1. The

SC802/A provides the capability, via the VPRGM pin, to

disconnect the external feedback resistor divider when

the charging source is removed, to reduce current drain

from the battery through the resistor network. Connect

the external resistor divider between the VOUT pins and

CHARGER VIN

Thermistor

1μF

2.2μF

BAT.

SC802/SC802A

VCC1

BSEN

IPRGM

EN_NTC

ITERM

VOUT2

RTIME

CHRGB

VPRGM

CPB

RFGND

BIPB

VCC2

GND

VOUT1

AFC

CHARGE

CHARGER

PRESENT

Figure 1. V