STBP120 Datasheet, PDF (7/36 Pages) STMicroelectronics – Overvoltage protection device with thermal shutdown

STBP120
2
Pin descriptions
Pin descriptions
2.1
Input (IN)
Input voltage pin. This pin is connected to the DC power supply. External low ESR ceramic
capacitor of minimum value 1 µF must be connected between IN and GND. This capacitor is
for decoupling and also protects the IC against dangerous voltage spikes and ESD events.
This capacitor should be located as close to the IN pins as possible.
All IN pins (4, 5) must be hardwired to common supply.
2.2
Power output (OUT)
Output voltage pin. This pin is connected to the input through a low R_DS(on) N-channel
MOSFET switch.
If no fault is detected and the STBP120 is not disabled (controlled by the EN input), this
switch is turned on and the output voltage follows the input voltage.
The output is disconnected from the input when the input voltage is under the UVLO
threshold or above the OVLO threshold, when the chip temperature is above the thermal
shutdown threshold or when the chip is disabled by the EN input.
There is a 50 ms delay, t_on, between input voltage or junction temperature returns to
specified range and the power output is connected to the input (see Figure 6).
All OUT pins (6, 7) must be hardwired to common supply.
2.3
Fault indication output (FLT)
The fault indication output (active-low - open-drain) provides information on the STBP120
state to the application controller. When FLT is active (i.e. driven low), this indicates the
STBP120 is in the undervoltage or overvoltage condition or thermal shutdown mode is
active. When the input voltage and junction temperature is in specified range, the FLT output
is in high impedance (Hi-Z) state.
There is an additional 50 ms delay, t_start, between the power output is connected to the input
and the FLT output is deactivated (i.e. in Hi-Z state) (see Figure 6).
Since the FLT output is of open-drain type, it may be pulled up by an external resistor R_P to
the controller supply voltage. If there is no need to use this output, it may be left
disconnected. The suitable R_P resistor value is in range of 10 kΩ to 1 MΩ.
To improve safety and to prevent damage to application circuits in the event of extreme
voltage or current conditions, an optional protective resistor R_FLT can be connected between
the FLT output and the controller input. The suitable R_FLT resistor value is in range of 22 kΩ
to 100 kΩ.
The function of the FLT output is not affected by the EN input state (see Figure 9).
Doc ID 15492 Rev 4
7/36