l4913adies STMicroelectronics, l4913adies Datasheet - Page 8

• Manufacturer Part Number: l4913adies
• Description: Rad-hard Positive Fixed Voltage Regulators
• Manufacturer: STMicroelectronics

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6.5
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Device description
The RHFL4913 adjustable voltage regulator contains a PNP type power element controlled
by a signal resulting from an 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.
ADJ pin
The load output voltage feedback comes from an external resistor divider bridge mid-point
connected to the ADJ pin (allowing all possible output voltage settings as per user
requirements) established between load terminals.
Inhibit ON-OFF control
By setting the INHIBIT pin TTL high, the device switches off the output current and voltage.
The device is ON when the INHIBIT pin is set low. Since the INHIBIT pin is pulled down
internally, it can be left floating in cases where the inhibit function is not used.
Overtemperature protection
A temperature detector internally monitors the power element junction temperature. The
device turns off when a temperature of approximately 175 °C is reached, returning to ON
mode when back to approximately 135 °C. Combined with the other protection blocks, the
device is protected from destructive junction temperature excursions in all load conditions. It
should be noted that when the internal temperature detector reaches 175 °C, the active
power element can be as high as 225 °C. Prolonged operation under these conditions far
exceeds the maximum operating ratings and device reliability cannot be guaranteed.
Overcurrent protection
An internal non fold-back short circuit limitation is set with I
value can be decreased via an external resistor connected between the I
a typical value range of 10 kΩ to 200 kΩ . To maintain optimal V
set I
I
flag is raised. When no current limitation adjustment is required, the I
unbiased (as it is in 3 pin packages).
OCM pin
The OCM pin goes low when the current limit becomes active, otherwise V
buffered and can sink 10 mA. The OCM pin is internally pulled up by a 5 kΩ resistor.
SHORT
SHORT
– 300 mA, the current limiter overrules the regulation, V
1.6 times greater than the maximum desired application I
SHORT
O
O
regulation, it is necessary to
starts to drop and the OCM
> 3.8 A (V
O
SC
. When I
SC
pin must be left
OCM
and V
O
is 0 V). This
O
= V
reaches
I
pins, with
I
. It is