5

Device description

The RHFL4913 fixed voltage contains a PNP type power element controlled by a signal resulting from amplified

comparison between the internal temperature compensated band-gap cell and the fraction of the desired

output voltage value. This fractional value is obtained from an internal-to-die resistor divider bridge set by

STMicroelectronics. The device is protected by several functional blocks.

5.1

Low pin count package limitations

Some functions (INHIBIT, OCM, SENSE) are not available due to lack of pins. Corresponding die pads are by

default connected inside silicon.

5.2

SENSE pin

The load voltage is applied by a Kelvin line connected to SENSE pin: Voltage feedback comes from the internal

divider resistor bridge. Therefore possible output voltages are set by manufacturer mask metal options. SENSE

pin is not available in 3-pin packages.

5.3

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. INHIBIT pin is not available in 3-pin packages.

5.4

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 40 °C. It

should be noted that when the internal temperature detector reaches 175 °C, the active power element can be at

225 °C: the device reliability cannot be guaranteed in case of extensive operation under these conditions.

5.5

Overcurrent protection

ISC pin. An internal non-fold back short-circuit limitation is set with ISHORT > 3.8 A (VO is 0 V). This value can be

reduced by an external resistor connected between ISC pin and VI pin,with a typical value range of 25 kΩ to 200

kΩ. This adjustment feature is not available in 3-pin packages. To keep excellent VO regulation, it is necessary to

set ISHORT 1.6 times greater than the maximum desired application IO. When IO reaches ISHORT – 300 mA, the

current limiter overrules regulation and VO starts to drop and the OCM flag is risen. When no current limitation

adjustment is required, ISC pin must be left unbiased (as it is in 3 pin-packages).

5.6

OCM pin

The OCM pin goes low when the current limit becomes active, otherwise VOCM = VI. It is buffered and can sink 10

mA. The OCM pin is internally pulled up by a 5 kΩ resistor. Not available in 3-pin packages.

5.7

Alternate to

The RHFL4913 fixed (and custom) voltages replace all 3-terminal industry devices, providing essential benefits

•

Lower dropout

•

High radiation performance

•

Better SVR

•

Saving the high stability external setting resistors

RHFL4913XX25, RHFL4913XX33, RHFL4913XX50

Device description

DS3260 - Rev 15

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