Datasheet

DocID17977 Rev 2 13/46
ST1S14 Function description
4.4 Error amplifier
The voltage error amplifier is the core of the loop regulation. It is a transconductance
operational amplifier whose non inverting input is connected to the internal voltage
reference (1.222 V), while the inverting input (FB) is connected to the external divider or
directly to the output voltage.
The error amplifier is internally compensated to minimize the size of the final application.
The error amplifier output is compared with the inductor current sense information to
perform PWM control.
4.5 Inhibit function
The inhibit feature is used to set the device in standby mode according to Table 2. When the
device is disabled, the power consumption is reduced to less than 40 µA. The EN2 pin is
also V
IN
compatible.
4.6 Thermal shutdown
The shutdown block generates a signal that turns off the power stage if the temperature of
the chip goes higher than a fixed internal threshold (150±10 °C). The sensing element of the
chip is very close to the PDMOS area, ensuring fast and accurate temperature detection. A
hysteresis of approximately 15 °C keeps the device from turning on and off continuously.
Table 7. Uncompensated error amplifier characteristics
Description Values
Transconductance 218 µS
Low frequency gain 93 dB
C
P
24 pF
C
C
211 pF
R
C
200 kΩ