RHFL4913_07 Datasheet, PDF (7/16 Pages) STMicroelectronics – Rad-Hard Adjustable positive voltage regulator

RHFL4913 ADJUSTABLE VERSION
4 Device description
Device description
The RHFL4913 Adjustable contains a PNP type power element controlled by a signal resulting from
amplified comparison between the internal temperature compensated Band-Gap and the fraction of the
desired Output Voltage value obtained from an external resistor divider bridge. The device is protected by
several functional blocks.
4.1 ADJ Pin
The Load output voltage feed-back comes from an external divider resistor bridge middle point connected
to ADJ pin (allowing all possible output voltage settings as per User’s desire) established between Load
terminals.
4.2 INHIBIT ON-OFF Control
By setting INHIBIT pin TTL-High, the Device switches off the Output Current and Voltage. Device is ON
when INHIBIT pin is set Low. Since INHIBIT pin is internally pulled down, it can be left floating in case
Inhibit function is not utilized.
4.3 Overtemperature protection
A temperature detector internally monitors the power element junction temperature. The Device goes
OFF when approx. 175°C are reached, returning to ON mode when back to approx. 40°C. Combined with
other protection blocks, it protects the Device from destructive junction temperature excursions in all load
conditions. It is worth noting that when internal temperature detector reaches 175°C, the active power
element can be at 225°C: Extensive operation under these conditions far exceeds Maximum Operation
Ratings and Device reliability cannot be granted.
4.4 Overcurrent protection
An internal non-fold back Short-Circuit limitation is set with I_SHORT > 3.8A (V_O is 0V). This value can be
downward modified by an external resistor connected between I_SC and V_I pins, with a typical value range
of 10kΩ to 200kΩ. To keep excellent V_O regulation, it is necessary to set I_SHORT 1.6 times greater than the
maximum desired application I_O. When I_O reaches I_SHORT – 300mA, the current limitor overrules
Regulation and V_O starts to drop and OCM flag is risen. When no current limitation adjustment is
required, I_SC pin must be left unbiased (as it is in 3pin packages).
4.5 OCM pin
Goes Low when current limit starts to be active, otherwise V_OCM = V_I. It is buffered and can sink 10mA.
OCM pin is internally pulled-up by a 5 kΩ resistor.
4.6 Alternates to
RHFL4913 is recommended to replace all Industry Positive Regulators due to its exceptional Radiation
performance. To replace 3-terminal Industry devices, use RHFL4913 Fixed Voltage versions.
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