TPS22946 Datasheet, PDF (19/30 Pages) Texas Instruments – ULTRA-LOW POWER,LOW INPUT VOLTAGE, CURRENT-LIMITED LOAD SWITCH WITH SHUT-OFF,AUTO-RESTART,AND OVER-CURRENT CONDITION TIME-OUT

TPS22946
www.ti.com......................................................................................................................................... SLVS984A – SEPTEMBER 2009 – REVISED OCTOBER 2009
APPLICATION INFORMATION
On/Off Control
The ON pin controls the state of the switch. Activating ON continuously holds the switch in the on state so long
as there is no fault. A junction temperature in excess of 150°C overrides the ON control to turn off the switch. ON
is active HIGH and has a low threshold making it capable of interfacing with low voltage signals. When the
MOSFET is off, the body diode is disabled so no current can flow through it from the input to the output, however
it does not prevent reverse current flowing.
Detection Schemes
Over-Temperature Detection
The thermal shutdown detection circuit is active every 8mS for a period of 0.5mS. The thermal shutdown protects
the part from internally or externally generated excessive temperatures. During an over-temperature condition the
switch is turned-off (Open). The switch automatically turns-on (closes) again if temperature of the die drops
below the threshold temperature while the part is still enabled.
In addition, if an over-current fault condition is detected due to a moderate over-current or a hard-short, the
thermal shutdown is activated immediately and stays on continuously for the duration of blanking (see Figure 3).
V_IN
V_IN/2
0V
V_ON is tied directly to V_IN
V_ON
0V
t_PWRON
V_OUT
Temperature (°C)
Over Temperature
Detection
V_OUT/2
Normal Temperature
140°C
Inrush current window
8mS
t
OVRTMP
0.5 ms
ON
OFF
ON
OFF
Over temperature detected
during the ON cycle
ON
129°C
Over Temperature
resumes the normal cycle
0.5 ms t
OVRTMP
OFF
ON OFF
Load Switch Status
SWITCH
OPEN
SWITCH
CLOSE
SWITCH
OPEN
SWITCH
CLOSE
NOTE: Case where the temperature causes the over-temperature detection circuit to trip before the other detection schemes.
Figure 26. Over-Temperature Detection
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