Datasheet

GC1
Fuse
VBAT
V
BAT
COMPC
DS
VIN
GC2
TPS43330-Q1
or
TPS43332-Q1
C14
Fuse (S1)
Q6
C13
C15C17
C16
D2
R10
Q7
D3
D1
TPS43330-Q1
or
TPS43332-Q1
GC2
VIN
DS
GC1
COMPC
VBAT
R9
V
BAT
L3
TPS43330-Q1
TPS43332-Q1
SLVSA82E –MARCH 2011–REVISED APRIL 2013 www.ti.com
During low-power mode, the EXTSUP functionality is not available. The internal regulator operates as a shunt
regulator powered from VIN and has a typical value of 7.5 V. Current-limit protection for VREG is available in
low-power mode as well. If EXTSUP is unused, leave the pin open without a capacitor installed.
External P-Channel Drive (GC2) and Reverse-Battery Protection
The TPS43330-Q1 and TPS43332-Q1 include a gate driver for an external P-channel MOSFET which can
connect across the rectifier diode of the boost regulator. Such connection is useful to reduce power losses when
the boost controller is not switching. The gate driver provides a swing of 6 V typical below the VIN voltage in
order to drive a P-channel MOSFET. When V
BAT
falls below the boost-enable threshold, the gate driver turns off
the P-channel MOSFET, eliminating the diode bypass.
Another use for the gate driver is to bypass any additional protection diodes connected in series, as shown in
Figure 24. Figure 25 also shows a different scheme of reverse battery protection, which may require only a
smaller-sized diode to protect the N-channel MOSFET, as the diode conducts only for a part of the switching
cycle. Because the diode is not always in the series path, the system efficiency can be improved.
Figure 24. Reverse-Battery Protection Option 1 for Buck-Boost Configuration
Figure 25. Reverse-Battery Protection Option 2 for Buck-Boost Configuration
Undervoltage Lockout and Overvoltage Protection
The TPS43330-Q1 and TPS43332-Q1 start up at a VIN voltage of 6.5 V (minimum), required for the internal
supply (VREG). Once it has started up, the device operates down to a VIN voltage of 3.6 V; below this voltage
level, the undervoltage lockout disables the device. Note: if V
IN
drops, V
REG
drops as well, hence reducing the
gate-drive voltage, whereas the digital logic is fully functional. Note as well, even if ENC is high, there is a
requirement to exceed the boost-unlock voltage of typically 8.5 V once, before boost activation can take place
(see the Boost Controller section herein). A voltage of 46 V at VIN triggers the overvoltage comparator, which
shuts down the device. In order to prevent transient spikes from shutting down the device, the under- and
overvoltage protection have filter times of 5 µs (typical).
When the voltages return to the normal operating region, the enabled switching regulators start including a new
soft-start ramp for the buck regulators.
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Product Folder Links: TPS43330-Q1 TPS43332-Q1