Datasheet
R4 1 MΩ
C1
10 µF
C
22 µF
OUT
L
VIN
EN
ILIM
GND
VOUT
FB
PG
R
20 k
ILIM
Ω
C
100 pF
FF
V
IN
R2
243 kΩ
L1
1 μH
R1
768 kΩ
V
OUT
U1
Power Good
Output
2.3 V to
6.0 V
3.0 V to
6.5 V
Enable
Logic Input
TPS61252
SLVSAG3 –SEPTEMBER 2010
www.ti.com
POWER GOOD
The device has a built in power good function to indicate whether the output voltage operates within appropriate
levels. The power good output (PG) is set high after the feedback voltage reaches 95% of its nominal value and
stays there until the feedback voltage falls below 90 % of the nominal value. The power good is operable as long
as the converter is enabled and V
IN
is present. If the converter is disabled by pulling the EN pin low the PG open
drain output is high resistive. That means it follows the voltage it is connected to via the pull-up resistor. If the
converter is controlled by an external enable signal and the power good should indicate that the output is turned
off the application circuit below should be used.
INPUT OVER VOLTAGE PROTECTION
This converter has a input over voltage protection that protects the device from damage due to a voltage higher
than the absolute maximum rating of the input allows. If 6.5 V (typ.) at the input is exceeded the converter
completely shuts down to protect its inner circuitry. If the input voltage drops below 6.4 V (typ.) it turns on the
device again and enters normal start up.
LOAD DISCONNECT AND REVERSE CURRENT PROTECTION
Regular boost converters do not disconnect the load from the input supply and therefore a connected battery will
be discharge during shutdown. The advantage of TPS61252 is that this converter is disconnecting the output
from the input of the power supply when it is disabled. In case of a connected battery it prevents it from being
discharge during shutdown of the converter.
THERMAL REGULATION
The TPS61252 contains a thermal regulation loop that monitors the die temperature. If the die temperature rises
to values above 110 °C, the device automatically reduces the current to prevent the die temperature from further
increasing. Once the die temperature drops about 10 °C below the threshold, the device will automatically
increase the current to the target value. This function also reduces the current during a short-circuit-condition.
THERMAL SHUTDOWN
As soon as the junction temperature, T
J
, exceeds 140°C (typical) the device enters thermal shutdown. In this
mode, the High Side and Low Side MOSFETs are turned-off. When the junction temperature falls about 20 °C
below the thermal shutdown, the device continuous the operation.
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Product Folder Link(s): TPS61252