isl88731a Intersil Corporation, isl88731a Datasheet - Page 10

• Manufacturer Part Number: isl88731a
• Description: Smbus Level 2 Battery Charger
• Manufacturer: Intersil Corporation

Undervoltage Detect and Battery Trickle Charging
If the voltage at CSON falls below 2.5V, the ISL88731A
reduces the charge current limit to 128mA to trickle charge
the battery. When the voltage rises above 2.7V the charge
current reverts to the programmed value in the
ChargeCurrent register.
Over-Temperature Protection
If the die temperature exceeds +150°C, it stops charging.
Once the die temperature drops below +125°C, charging will
start up again.
10
FIGURE 15. OVERVOLTAGE PROTECTION IN ISL88731
ISL88731A
Overvoltage Protection
ISL88731 has an Overvoltage Protection circuit that limits
the output voltage when the battery is removed or
disconnected by a pulse charging circuit. If CSON exceeds
the output voltage set point in the chargevoltage register by
more than 300mV an internal comparator pulls VCOMP
down and turns off both upper and lower FETs of the buck as
in Figure 15. There is a delay of approximately 1µs between
V
LGATE and UGATE low. After UGATE and LGATE are
turned OFF inductor current continues to flow through the
body diode of the lower FET and V
inductor current reaches zero.
OUT
exceeding the OVP trip point and pulling VCOMP,
OUT
continues to rise until
January 7, 2009
FN6738.1