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6 of 10
SS6821
BLOCK DIAGRAM
Power-down
Control
Wake-up Control
-0.3V
3
4
1
2
5
VCC
Overdischarge
Delay Circuit
Overcharge
Delay Circuit
Overcurrent
Delay Circuit
Enable
Enable
Load Detected
0.3V
0.2V
CS
GND
OC
OD
1.2V
1V
PIN DESCRIPTIONS
PIN 1: OC
- PMOS open drain output for control
of the charge control MOSFET M2.
In normal mode, this PMOS turns
on to pull the gate of the MOSFET
M2 high, and the MOSFET M2 turns
on. When over-charge occurs, this
PMOS turns off, no current flows
through R3 and the MOSFET M2
turns off.
PIN 2: GND - Ground pin. This pin is to be
connected to the negative terminal
of the battery cell.
PIN 3: OD
- Output
pin
for
control
of
the
discharge
control
MOSFET
M1.
When over-discharge occurs, this
pin
goes
low
to
turn
off
the
MOSFET M1 and discharging is
halted.
PIN 4: CS
- Input pin for current sensing. Using
the
sum
of
the
drain-source
voltages of the MOSFET M1 and
the MOSFET M2 (voltage between
CS
and
GND),
it
senses
the
discharge current during normal
mode and detects whether charging
current is present during the power-
down mode. It is also used to detect
whether
the
load
is
connected
during over-charge mode.
PIN 5: VCC - Power supply pin. This pin is to be
connected to the positive terminal of
the battery cell.
12/6/2004 Rev.2.02