isl9212 Intersil Corporation, isl9212 Datasheet - Page 7

• Manufacturer Part Number: isl9212
• Description: Charging System Safety Circuit
• Manufacturer: Intersil Corporation

Typical Operating Performance
Theory of Operation
The ISL9212 is an integrated circuit (IC) optimized to provide
a redundant safety protection to a Li-ion battery from
charging system failures. The IC monitors the input voltage,
the battery voltage, and the charge current. When any of the
above three parameters exceeds its limit, the IC turns off an
internal P-channel MOSFET to remove the power from the
charging system. In addition to the above protected
parameters, the IC also monitors its own internal
temperature and turns off the P-channel MOSFET when the
temperature exceeds 140°C. Together with the battery
charger IC and the protection module in a battery pack, the
charging system has triple-level protection from over-
charging the Li-ion battery and is two-fault tolerant. The
ISL9212 protects up to 30V input voltage.
FIGURE 20. EN INPUT THRESHOLD vs TEMPERATURE
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
-50
FIGURE 22. ON RESISTANCE vs TEMPERATURE AT DIFFERENT INPUT VOLTAGES AND LOAD CURRENTS
-20
TEMPERATURE (°C)
10
7
40
70
0.35
0.30
0.25
0.20
0.15
0.10
0.05
The test conditions for the Typical Operating Performance are: V
R
100
0
-50
ILIM
FROM TOP TO BOTTOM V
3V/1.5A, 3V/0.5A, 4.6V/1.5A, 4.6V/0.5A,
5V/1.5A, 5V/0.5A, 6.5V/1.5A, AND 6.5V/0.5A
= 25.5kΩ, R
130
-20
ISL9212
TEMPERATURE (°C)
10
VB
= 200kΩ, Unless Otherwise Noted. (Continued)
40
Power-Up
The ISL9212 has a power-on reset (POR) threshold of 2.6V
with a built-in hysteresis of 100mV. Before the input voltage
reaches the POR threshold, the internal power PFET is off.
Approximately 10ms after the input voltage exceeds the
POR threshold, the IC resets itself and begins the soft-start.
The 10ms delay allows any transients at the input during a
hot insertion of the power supply to settle down before the IC
starts to operate. The soft-start slowly turns on the power
PFET to reduce the inrush current as well as the input
voltage drop during the transition. The power-up behavior is
illustrated in Figure 2.
Input Overvoltage Protection (OVP)
The input voltage is monitored by the comparator CP1 in the
Block Diagram (Figure 1). CP1 has an accurate reference of
1.2V from the bandgap reference. The OVP threshold is set
by the resistive divider consisting of R1 and R2. The
IN
FIGURE 21. EN PIN INTERNAL PULL-DOWN RESISTANCE
AND I
70
LOAD
250
240
230
220
210
200
190
180
170
160
150
100
-50
ARE:
130
-20
TEMPERATURE (°C)
10
40
IN
= 5V, T
70
A
= 25°C,
100
May 8, 2006
130
FN9280.1