gs-r24p0501.5 STMicroelectronics, gs-r24p0501.5 Datasheet - Page 5

• Manufacturer Part Number: gs-r24p0501.5
• Description: 1.8w Step-down Switching Regulator Family
• Manufacturer: STMicroelectronics

GS-R24P
USER NOTES
Input Voltage
The recommended operating maximum DC Input Voltage is 35V inclusive of ripple voltage.
Inhibit function
The inhibit feature allows to put in stand-by mode the device.
With INH pin 4 higher than 2.2V the device is disabled and the power consumption is reduced to less than
150µA for V
= 35V.
i
With INH pin lower than 0.8V, the device is enabled.
If the INH pin is left floating, an internal pull up ensures that the voltage at the pin reaches the inhibit threshold
and the device is disabled.
The pin is also V
compatible.
i
Current protection
The device has two current limit protections, pulse by pulse and frequency fold back.
The current is sensed through a resistor and if reaches the threshold, the on time is reduced and consequently
the output voltage too.
Since the minimum switch ON time (necessary to avoid false overcurrent signal) is not enough to obtain a suf-
ficiently low duty cycle at 250 Hz, the output current, in strong overcurrent or short circuit conditions, could in-
crease again.
For this reason the switching frequency is also reduced, so keeping the inductor current under its maximum
threshold.
The frequency depends on the feedback voltage.
As the feedback voltage decreases (due to the reduced duty cycle), the switching frequency decrease too.
Thermal shutdown
The shutdown block generates a signal that turns off the power stage if the temperature of the internal chip goes
higher than a fixed internal threshold (150 ºC).
The sensing element of the chip is very close to the PDMOS area, so ensuring an accurate and fast temperature
detection.
An hysteresis of approximately 20ºC avoids that the devices turns on and off continuously.
Thermal Characteristics
Output voltage programming (GS-R24H(S)0001.5 only)
The GS-R24P output voltage is 5.54V ±4%, to reduce this value connect a resistor between pin 6 (FB) and
pin 5 (V
).
out-c
The resistor must be located very close to the proper pins, to minimize the injected noise (see figure 1).
The resistor value is calculated using the following formula:
Rv=[(V
-1.235)*11.3]/(5.54-V
) --[kOhm]
out
out
V
can be adjusted between 1.235V (Rv=0 Ohm) and 5.54V (Rv=open)
out
5/7