SC804 datasheet(14/21 Pages) SEMTECH

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SC804

PRELIMINARY

POWER MANAGEMENT

FLAG

OFF

CPB

UVLO < VCC < OVP

Input out of range

CHRGB

IOUT > ITERM

IOUT < ITERM

OVPB

VCC > OVP

VCC < OVP

FLTB

VCC > OVP

VCC UVLO

NTC Temp Fault

Pre-Charge Time-out

(OT (Tj > 150°C)

Normal Operation

or NTC Disable

Applications Information (Cont.)

Charge Mode Timing Diagram

VCC

VOUT

IOUT

CPB

CHRGB

TIMER

FLTB

NTC

UVLO

2.8V

Pre- Charge

Soft Start

Fast Charge

Termination

Current

Re- Charge

Threshold

CC Mode

CV Mode

Off

Fault

Hold

Figure 5 - Charge Mode Timing

The CHRGB output indicates the charging status. When

the output current is greater than ITERM, CHRGB is low.

CHRGB is high impedance when IOUT is less than ITERM.

The CHRGB output is latched during the charge cycle when

the output current is less than ITERM. This latch is reset

when the battery enters a recharge cycle, or if NTC or VCC

are toggled.

The OVPB signal is an active-low output that signals when

the input voltage exceeds the OVP threshold. When the

voltage on VCC is less than the OVP threshold voltage this

output is high impedance. The FLTB output is activated

when the SC804 experiences a fault condition. This out-

put can be used to notify the system controller of a fault

condition when connected to an interrupt input, or it can

be used like CPB and CHRGB to drive an indicator LED.

The ﬁve fault modes signaled by FLTB are: input over-volt-

age, input under-voltage, NTC temperature out of range,

max die temperature (OT), and pre-charge time-out. When

any of these conditions occurs the FLTB output goes low;

otherwise it remains high impedance.

Capacitor Selection

Low cost, low ESR ceramic capacitors such as the X5R

and X7R dielectric material types are recommended for

use with the SC804. The output capacitance range is 1μF

to 4.7μF. The input capacitor is typically between 0.1μF to

1μF, but Charge Mode Timing Diagram larger values will

not degrade performance.

SC804 Datasheet(PDF) 14 Page - Semtech Corporation

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