RHFL4913A STMICROELECTRONICS [STMicroelectronics], RHFL4913A Datasheet - Page 10

• Manufacturer Part Number: RHFL4913A
• Description: Rad-hard adjustable positive voltage regulator
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Application information
6
6.1
6.2
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Application information
To adjust the output voltage, the R2 resistor must be connected between the V
pins. The R1 resistor must be connected between ADJ and ground. Resistor values can be
derived from the following formula:
V
The V
The minimum output voltage is therefore 1.22 V and minimum input voltage is 3 V.
The RHFL4913A adjustable is functional as soon as the V
above the power element saturation voltage. The adjust pin to ground resistor value must
not be greater than 10 kΩ, in order to keep the output feedback error below 0.2%. A
minimum of 0.5 mA I
dissipate this current into the divider bridge resistor. All available V
available V
reliability of the device cannot be guaranteed. The inhibit function switches off the output
current electronically, and therefore very quickly. According to Lenz’s Law, external circuitry
reacts with LdI/dt terms which can be of high amplitude in case somewhere a serial coil
inductance exists. Large transient voltage would develop on both device terminals. It is
advisable to protect the device with Schottky diodes to prevent negative voltage excursions.
In the worst case, a 14 V Zener diode could protect the device input. The device has been
designed for high stability and low dropout operation. Therefore, tantalum input and output
capacitors with a minimum 1 µF are mandatory. Capacitor ESR range is from 0.01 Ω to over
20 Ω. This range is useful when ESR increases at low temperature. When large transient
currents are expected, larger value capacitors are necessary.
In the case of high current operation with short circuit events expected, caution must be
exercised with regard to capacitors. They must be connected as close as possible to the
device terminals. As some tantalum capacitors may permanently fail when subjected to high
charge-up surge currents, it is recommended to decouple them with 470 nF polyester
capacitors.
Since the RHFL4913A adjustable voltage regulator is manufactured with very high speed
bipolar technology (6 GHz f
care, with very low inductance and low mutually coupling lines. Otherwise, high frequency
parasitic signals may be picked up by the device resulting in system self-oscillation. The
benefit is an SVR performance extended to far higher frequencies.
Notes on the 16-pin hermetic package
The bottom section of the 16-pin package is metallized in order to allow the user to directly
solder the RHFL4913A onto the equipment heat sink for enhanced heat removal.
Remote sensing operation
A separate kelvin voltage sensing line provides the ADJ pin with exact load "high potential"
information (see
Iq current (Iq is roughly the I
element) routed through the parasitic series line resistor RW2. To compensate for this
O
= V
ADJ
ADJ
is 1.23 V, controlled by the internal temperature-compensated band gap block.
(R1+ R2) / R1
O
pins, should always be externally interconnected, otherwise the stability and
Figure
O
must be set to ensure perfect no-load regulation. It is advisable to
3). But variable remote load current consumption induces variable
T
O
transistors), the PCB layout must be designed with exceptional
Doc ID 10005 Rev 11
current divided by the h
FE
of the internal PNP series power
I
- V
O
voltage difference is slightly
I
pins, as well as all
O
RHFL4913A
and ADJ