Datasheet

TPS61175
SLVS892B –DECEMBER 2008–REVISED FEBRUARY 2012 www.ti.com
ENABLE AND THERMAL SHUTDOWN
The TPS61175 enters shutdown when the EN voltage is less than 0.4-V for more than 10-ms. In shutdown, the
input supply current for the device is less than 1.5-μA (max). The EN pin has an internal 800-kΩ pull down
resistor to disable the device when it is floating.
An internal thermal shutdown turns off the device when the typical junction temperature of 160°C is exceeded.
The IC restarts when the junction temperature drops by 15°C.
UNDER VOLTAGE LOCKOUT (UVLO)
An under voltage lockout circuit prevents mis-operation of the device at input voltages below 2.5-V (typical).
When the input voltage is below the under voltage threshold, the device remains off and the internal switch FET
is turned off. The under voltage lockout threshold is set below minimum operating voltage of 2.9V to avoid any
transient VIN dip triggering the UVLO and causing the device to reset. For the input voltages between UVLO
threshold and 2.9V, the device attempts to operate, but the specifications are not ensured.
MINIMUM ON TIME and PULSE SKIPPING
Once the PWM switch is turned on, the TPS61175 has minimum ON pulse width of 60-ns. This sets the limit of
the minimum duty cycle of the PWM switch, and it is independent of the set switching frequency. When operating
conditions result in the TPS61175 having a minimum ON pulse width less than 60-ns, the IC enters pulse-
skipping mode. In this mode, the device keeps the power switch off for several switching cycles to keep the
output voltage from rising above the regulated voltage. This operation typically occurs in light load condition
when the PWM operates in discontinuous mode. Pulse skipping increases the output voltage ripple, see the
Figure 14.
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