FAN54300 Datasheet, PDF (29/43 Pages) Fairchild Semiconductor – USB-Compliant, Dual-Power Input, Single-Cell, Li-Ion Switching Charger with USB-OTG Boost Regulator

Input Over-Voltage Detection
When VBUS exceeds its OVP threshold, the IC:
1. Turns off Q3;
2. Suspends charging from VBUS; and
3. Sets the FAULTU bits to 001, STATU bits to 11, and
pulses the STAT pin.
When VBUS falls to about 150 mV below VBUSOVP, the fault is
cleared, and charging resumes after VBUS is revalidated.
If VIN exceeds its OVP threshold, the IC:
1. Turns off Q4;
2. Suspends charging from VIN; and
3. Sets the FAULTV bits to 001, STATV bits to 11, and
pulses the STAT pin.
Charge Mode Battery Detection & Protection
V_BAT Over-Voltage Protection
The OREG voltage regulation loop prevents VBAT from
overshooting the OREG voltage by more than 50 mV when
the battery is removed. When the PWM charger is running
with no battery, the TE bit is not set, and a battery is inserted
that’s charged to a voltage higher than VOREG; PWM pulses
stop. If no further pulses occur for 30 ms, the IC sets the
FAULT bits to 100, STAT bits to 11, and pulses the STAT pin.
Battery Detection During Charging
The IC can detect presence, absence, or removal of a battery.
During normal charging, once VBAT is greater than VOREG –
VRCH and the termination charge current is detected; the IC
terminates charging and sets the STAT bits to 10. It then turns
on a discharge current, IDETECT, for tDETECT . If VBAT is still above
VOREG – VRCH, the battery is present and the IC sets the
FAULT bits to 000. If VBAT is below VOREG – VRCH, the battery
is absent and the IC:
1. Sets the registers to their default values;
2. Sets the FAULT bits to 111; and
3. Resumes charging with default values after delay tINT.
Battery Detection During Power-up
At PWRIN POR, if the charger is in 15-Minute Mode (no I²C
writes from the host detected), the IC starts a 32 ms timer
when VBAT crosses VSHORT and starts PWM charging. If VBAT
exceeds 3.7 V within a 32 ms period, the IC determines that
the battery is not present and:
1. Enters Charge Configuration Mode;
2. Sets the FAULT bits to 111 (no battery) and resets the
SAFETY registers; and
3. Disables auto-charging until the next PWRIN POR.
Battery Short-Circuit Protection
If the battery voltage is below the short-circuit threshold
(VSHORT); a linear current source, ISHORT, supplies VBAT until
VBAT > VSHORT.
Charger Status / Fault Status
The STAT pin indicates the operating condition of the IC and
provides a fault indicator for interrupt-driven systems. When a
fault condition occurs, the STAT pin pulses LOW for 125 s. If
a new fault replaces the prior fault, STAT issues a new pulse.
The FAULT bits ( R0[2:0] ) indicate the type of fault in Charge
Mode (see Table 14). FAULT bits return to 000 once R0 is
read if the fault condition has cleared.
Charge Mode Control Bits
When set, the HZ_VBUS and HZ_VIN bits prevent charging
from the VBUS or VIN input sources, respectively. The DIS pin
prevents all charging when set, regardless of the state of the
HZ bits.
Table 6. DIS Pin and HZ Bit Functionality
Charging
DIS PIN
HZ
ENABLE
0
0
DISABLE
X
1
DISABLE
1
X
Boost Mode
Boost Mode can be enabled when the IC is in 32-Second Mode
(host sets TMR_RST before the t32SEC expired ) with the OTG
pin and OPA_MODE bits as indicated in Table 7. The OTG
ACTIVE state is 1 if OTG_PL =1, and 0 when OTG_PL =0.
If boost is active using the OTG pin, boost mode is initiated
even if the HZ_VBUS = 1. The HZ_VBUS bit overrides the
OPA_MODE bit.
Table 7. Enabling Boost
OTG_E
N
OTG PIN
HZ_VBU
S
OPA_MOD
E
BOOS
T
1
ACTIVE
X
1
X
0
X
Enabled
1
Enabled
1
ACTIVE
0
0
Disabled
1
ACTIVE
X
0
X
1
0
Disabled
X
Disabled
To remain in Boost Mode, the TMR_RST bit must be set by
the host before the t32SEC timer expires. If t32SEC times out in
Boost Mode; the IC reverts to High-Impedance Mode, pulses
the STAT pin, sets the FAULT bits to 110, and resets the
BOOST bit. POR or USB activity clears the fault condition.
The IC can operate its boost regulator while simultaneously
charging from VIN. If the IC is charging from VIN when the
boost regulator is enabled, charging pauses until the boost
soft-start has completed.
© 2010 Fairchild Semiconductor Corporation
FAN54300 • Rev. 1.0.4
29
www.fairchildsemi.com