Datasheet

TPS62110, TPS62111
TPS62112, TPS62113
SLVS585C –JULY 2005–REVISED OCTOBER 2012 www.ti.com
ENABLE
A logic low on EN forces the TPS6211x into shutdown. In shutdown, the power switch, drivers, voltage reference,
oscillator, and all other functions are turned off. The LBO pin is high impedance, while PG is held low. The
supply current is reduced to less than 2 µA in the shutdown mode. When the device is in thermal shutdown, the
band gap is forced to be switched on even if the device is set into shutdown by pulling EN to GND.
If an output voltage is present when the device is disabled, which could be due to an external voltage source or a
super capacitor, the reverse leakage current is specified under electrical characteristics. Pulling the enable pin
high starts up the TPS6211x with the soft start. If the EN pin is connected to any voltage other than V
I
or GND,
an increased leakage current of typically 10 µA and up to 20 µA can occur. See SLVA295 for details.
UNDERVOLTAGE LOCKOUT
The undervoltage lockout circuit prevents the device from misoperation at low-input voltages. It prevents the
converter from turning on the switch or rectifier MOSFET under undefined conditions. The minimum input voltage
to start up the TPS6211x is 3.4 V (worst case). The device shuts down at 2.8 V minimum.
THERMAL SHUTDOWN
The junction temperature (T
J
) of the device is monitored by an internal temperature sensor. If T
J
exceeds 145°C
typical, the device goes into thermal shutdown. Both the high-side and low-side power FETs are turned off and
PG goes high impedance. When T
J
decreases by typically 10°C, the converter resumes normal operation.
SYNCHRONIZATION
If no clock signal is applied, the converter operates with a typical switching frequency of 1 MHz. It is possible to
synchronize the converter to an external clock within a frequency range from 0.8 MHz to 1.4 MHz only. The
device automatically detects the rising edge of the first clock and synchronizes immediately to the external clock.
If the clock signal is stopped, the converter automatically switches back to the internal clock and continues
operation. The switch over is initiated if no rising edge on the SYNC pin is detected for a duration of four clock
cycles. Therefore, the maximum delay time can be 6.25 µs if the internal clock has its minimum frequency of 800
kHz.
If the device is synchronized to an external clock, the power-save mode is disabled, and the devices stay in
forced PWM mode.
Connecting the SYNC pin to the GND pin enables the power-save mode. The converter operates in the PWM
mode at moderate-to-heavy loads, and in the PFM mode during light loads, which maintains high efficiency over
a wide load-current range.
POWER-GOOD COMPARATOR
The power-good (PG) comparator is an open-drain output capable of sinking 1 mA (typical). The PG is only
active when the device is enabled (EN = high). When the device is disabled (EN = low), the PG pin is pulled to
GND.
The PG output is only valid after a 250-µs delay when the device is enabled and the supply voltage is greater
than the undervoltage lockout V
(UVLO)
.
The PG pin becomes active-high when the output voltage exceeds 98.4% (typical) of its nominal value. Leave
the PG pin floating or grounded when not used.
LOW-BATTERY DETECTOR (Standard Version)
The low-battery output (LBO) is an open-drain type which goes low when the voltage at the low-battery input
(LBI) falls below the trip point of 1.256 V ±1.5%. The voltage at which the low-battery warning is issued can be
adjusted with a resistive divider as shown in Figure 19. The sum of resistors (R1 + R2) as well as the sum of (R5
+ R6) is recommended to be in the 100-kΩ to 1-MΩ range for high efficiency at low output current. An external
pullup resistor can be connected to V
O
, or any other voltage rail in the voltage range of 0 V to 17 V. During start-
up, the LBO output signal is invalid for the first 500 µs. LBO is high-impedance when the device is disabled. If the
low-battery comparator function is not used, connect LBI to ground. The low-battery detector is disabled when
the device is disabled.
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