Copyright ANPEC Electronics Corp.
Rev. A.2 - Nov., 2009
APL3208A/B/C
www.anpec.com.tw9
Function Description
ACIN Power-On-Reset (POR)
The APL3208A/B/C has a built-in power-on-reset circuit
to keep the output shutting off until internal circuitry is
operating properly. The POR circuit has hysteresis and a
de-glitch feature so that it will typically ignore undershoot
transients on the input. When the input voltage exceeds
the POR threshold and after 8ms blanking time, the out-
put voltage starts a soft-start to reduce the inrush current.
ACIN Over-Voltage Protection (OVP)
The input voltage is monitored by the internal OVP circuit.
When the input voltage rises above the input OVP
threshold, the internal FET will be turned off within 1ms to
protect the connected system on OUT pin. When the in-
put voltage returns below the input OVP threshold minus
the hysteresis, the FET is turned on again after 8ms re-
covery time. The input OVP circuit has a 200mV hyster-
esis and a recovery time of TON(OVP) to provide noise im-
munity against transient conditions.
Battery Over-Voltage Protection
The APL3208A/B/C monitors the VBAT pin voltage for bat-
tery over-voltage protection. The battery OVP threshold is
internally set to 4.35V. When the VBAT pin voltage ex-
ceeds the battery OVP threshold for a blanking time of TB
(BOVP), the internal power FET is turned off. When the VBAT
voltage returns below the battery OVP threshold minus
the hysteresis, the FET is turned on again. The APL3208A/
B/C has a built-in counter. When the total count of battery
OVP fault reaches 16, the FET is turned off permanently,
requiring a VACIN POR again to restart.
Over-Temperature Protection
When the junction temperature exceeds 160oC, the inter-
nal thermal sense circuit turns off the power FET and
allows the device to cool down. When the device’s junc-
tion temperature cools by 40oC, the internal thermal
sense circuit will enable the device, resulting in a pulsed
output during continuous thermal protection. Thermal pro-
tection is designed to protect the IC in the event of over
temperature conditions. For normal operation, the junc-
tion temperature cannot exceed TJ=+125oC.
Internal P-MOSFET
The APL3208A/B/C integrates a P-channel MOSFET with
the body diode reverse protection to replace the external
power bipolar transistor and Schottky diode for the Infineon
ULC2 mobile. The body diode reverse protection pre-
vents a reverse current flowing from the battery back to
the CHG_DET pin. During power-on, when CHG_DET
voltage rises above the VBAT voltage by more than
120mV, the body diode of the P-channel MOSFET is for-
ward biased from OUT to CHG_DET, and P-MOSFET is
controlled by the external CHG_SW voltage. When the
CHG_DET voltage drops below VBAT+20mV, the body di-
ode of the P-channel MOSFET is forward biased from
CHG_DET to OUT and P-channel MOSFET is turned off.
When any of input OVP, battery OVP, is detected,the inter-
nal P-channel MOSFET is also turned off.
Current-Limit Protection
The APL3208A/B/C provides a current-limit protection
function. When the current via the internal switch sur-
passes the current limit threshold, the current will be
clamped to a constant level to provide external battery
charging current.