l7913adie2v STMicroelectronics, l7913adie2v Datasheet - Page 10

• Manufacturer Part Number: l7913adie2v
• Description: Rad-hard Adjustable Negative Voltage Regulator
• Manufacturer: STMicroelectronics

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Application information
Adjusting output voltage: R1 resistor must be connected between V
resistor must be connected between ADJ and GND pins. Resistor values can be derived
from the following formula:
V
To access all RHFL7913 adjustable functionality, V (+) shall be set at 3.0 V (max 5 V). As a
consequence, V
operation rating.
The device is functional as soon as V
element saturation voltage. The adjustable pin to Ground resistor shall not be greater than
10 kΩ to make output feedback error be below 0.2%. A minimum 0.5 mA I
set to ensure perfect “no-load” regulation. It can be wise to dissipate this current into the
divider bridge resistor.
All available V
otherwise device stability and reliability cannot be granted. The INHIBIT function switches
off output current in an electronic way, is very quickly. According to Lenz’ Law, external
circuitry reacts with –LdI/dt terms which can be of high amplitude in case some series-
inductance exists. Effect would be large transient voltage developed on both device
terminals. External Schottky diodes may prevent voltage excursions beyond max ratings. In
the worst case, a 14 V Zener diode shall protect the device input. In case of inductive load, a
input-output protection diode can be necessary to prevent V
transient operation.
The device has been designed for high stability and low drop out operation: minimum 1 µF
input and output tantalum capacitors are therefore mandatory. Typical industry PCB design
practices 10 µF capacitors values are acceptable. Capacitor ESR range is from 0.5 Ω to over
20 Ω . Such range turns out to be useful when ESR increases at low temperature. When
large transient currents are expected, larger value capacitors are necessary.
In case of high current operation with expected short-circuit events, caution shall be
considered relatively to capacitors. They shall be connected as close as possible form
device terminals. As some tantalum capacitors may permanently fail when submitted to high
charge-up surge currents, it is recommended to decouple them with 470 nF polyester
capacitors.
RHFL7913 adjustable being manufactured with very high speed bipolar technology (6 GHz
f
inductance, low mutually coupling lines, otherwise high frequency parasitic signals may be
picked-up by the Device resulting into system self-oscillation. In difficult high current
circumstances (coming from PCB layout) a 470 nF polyester capacitor connected between
V
higher frequencies.
T
O
O
transistors), the PCB layout shall be performed with unprecedented care, very low
= V
and ADJ pin increases stability margins. Benefit is SVR performances extended to far
ADJ
(1 + R1/R2) with V
I
pins shall always be PCB interconnected, the same for all available V
I
(-) cannot be greater than –9.0 V (resp. –7 V) due to –12 V maximum
ADJ
= -1.20 V
I
- V
O
voltage difference is slightly above power
O
to be greater than V
O
and ADJ pins. R2
O
is necessary to
I
during
O
pins,