BQ24295 Datasheet, PDF (20/45 Pages) Texas Instruments – I2C Controlled 3A Single Cell USB Charger

bq24295
SLUSBC1 – SEPTEMBER 2013
www.ti.com
New Fault Register REG09^(1)(2)(3)
BIT
DESCRIPTION
Bit 7
WATCHDOG_FAULT 0 – Normal, 1- Watchdog timer expiration
Bit 6
OTG_FAULT
0 – Normal, 1 – VBUS overloaded in OTG, or VBUS OVP, or battery is too low (any conditions that we
cannot start boost function)
Bit 5
Bit 4
CHRG_FAULT[1]
CHRG_FAULT[0]
00 – Normal, 01 – Input fault (OVP or bad source), 10 - Thermal shutdown,
11 – Charge Timer Expiration
Bit 3
BAT_FAULT
0 – Normal, 1 – System OVP
Bit 2
Reserved
Reserved – 0
Bit 1
NTC_FAULT[1]
0-Normal 1–Cold Note: Cold temperature threshold is different based on device operates in buck or
boost mode
Bit 0
NTC_FAULT[0]
0-Normal 1–Hot Note: Hot temperature threshold is different based on device operates in buck or boost
mode
(1) REG09 only supports single byte i2c read.
(2) All register bits in REG09 are latched fault. First time read of REG09 will clear the previous fault and second read will update fault
register to any fault that still presents.
(3) When adapter is unplugged, input fault (bad source) in CHRG_FAULT bits[5:4] will be set to 01 once.
Vender / Part / Revision Status Register REG0A
BIT
DESCRIPTION
Bit 7
PN[2]
110 (bq24295)
Bit 6
PN[1]
Bit 5
PN[0]
Bit 4
Reserved
0 – Reserved
Bit 3
Reserved
0 – Reserved
Bit 2
Rev[2]
000
Bit 1
Rev[1]
Bit 0
Rev[0]
DETAILED DESCRIPTION
The bq24295 is an I²C controlled power path management device and a single cell Li-Ion battery charger. It
integrates the input reverse-blocking FET (RBFET, Q1), high-side switching FET (HSFET, Q2), low-side
switching FET (LSFET, Q3), and battery FET (BATFET, Q4) between system and battery. The device also
integrates the bootstrap diode for the high-side gate drive.
Device Power Up
Power-On-Reset (POR)
The internal bias circuits are powered from the higher voltage of VBUS and BAT. When VBUS or VBAT rises
above UVLOZ, the sleep comparator, battery depletion comparator and BATFET driver are active. I2C interface
is ready for communication and all the registers are reset to default value. The host can access all the registers
after POR. By default, the BATFET driver is inactive when battery power is first applied. The BATFET driver can
be enabled by plugging in DC source, by clearing BATFET_Disable bit (REG07[5]), or logic low to high transition
on QON pin.
Power Up from Battery without DC Source
If only battery is present and the voltage is above depletion threshold (V_{BAT_DEPL}), the BATFET turns on and
connects battery to system. The REGN LDO stays off to minimize the quiescent current. The low R_DSON in
BATFET and the low quiescent current on BAT minimize the conduction loss and maximize the battery run time.
During both boost and charge mode, the device always monitors the discharge current through BATFET. When
the system is overloaded or shorted, the device will immediately turn off BATFET and keep BATFET off until the
input source plugs in again.
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