Rainbow Electronics MAX4880 - Manual (Page 5)

MAX4880
Overvoltage-Protection Controller with
Internal Disconnect Switch
_______________________________________________________________________________________ 5
CURRENT LIMIT vs. TEMPERATURE
TEMPERATURE ( °C)
CURRENT LIMIT (mA)
MAX4880 toc11
-40 -15 10 35 60 85
0
100
200
300
400
500
600
700
800
V
CB
= 5V
V
BTA
= 5V
V BTB = 3.6V
CURRENT LIMIT vs. V BTB
V BTB (V)
CURRENT LIMIT (mA)
MAX4880 toc12
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
0
100
200
300
400
500
600
700
800
V
CB
= 5V
V
BTA
= 5V
Pin Description
Typical Operating Characteristics (continued)
(V
IN
= 5V, TA = +25 °C, otherwise noted.)
PIN NAME FUNCTION
1 IN
Input. IN is the power input for the overvoltage (OVP) charge pump. Bypass IN to GND with a 1µF or
larger capacitor to achieve 15kV ESD protection.
2 EN
Active-Low Enable Input. Driving EN high turns off the external MOSFET. Pulling EN low activates the
overvoltage-protection circuitry and turns on the external MOSFET.
3 GATE
Gate-Drive Output. GATE is the output of an on-chip OVP charge pump. When V UVLO < V IN < V OVLO ,
GATE is driven high to turn on the external n-channel MOSFET. When V
IN (MIN)
< V
IN
< V
UVLO
or V
IN
>
V OVLO , GATE is driven low to turn off the external n-channel MOSFET.
4 BTA
Input Terminal for the Internal-Current-Limited Switch. Connect BTA to the source of the external n-
channel MOSFET. BTA is the power input for the entire device (except the OVP charge pump). Bypass
BTA to GND with a 0.1µF capacitor as close to the device as possible.
5 CB
Control Input for the Internal-Current-Limited Switch. Drive CB high to leave the internal switch control for
the internal logic. The internal switch turns on and off depending on the battery voltage level. The internal
switch turns off when the battery voltage reaches the BTB trip level (4.2V), and turns back on when the
battery falls by 200mV. Driving CB low turns off the internal switch regardless of the battery voltage.
6 GND Ground
7 BTB
Output Terminal for the Internal-Current-Limited Switch. When the BTB voltage exceeds the trip level
(4.2V), the internal switch opens. The switch closes only when the BTB voltage drops 200mV below the
trip level.
8 BTB_SNS
Battery-Voltage-Sensing Input. BTB_SNS must be connected to BTB for proper operation. Bypass
BTB_SNS to GND with a 0.1µF capacitor as close to the device as possible.
9 BAT_OK
Active-Low, Open-Drain, Battery-Voltage-Limit Flag Output. BAT_OK asserts low when the voltage on BTB
exceeds the BTB trip level (4.2V). BAT_OK is disabled when EN goes high.