LR12_13 Datasheet, PDF (1/10 Pages) Supertex, Inc – High Input Voltage, Adjustable 3-Terminal Linear Regulator

Supertex inc.
LR12
High Input Voltage, Adjustable
3-Terminal Linear Regulator
Features
►► 13.2 to 100V input voltage range
►► Stable with 100nF output capacitor
►► Adjustable 1.20 to 88V output regulation
►► 5% reference voltage tolerance
►► Output current limiting, 50mA min.
►► 10µA typical ADJ current
►► Over temperature protection
►► Available in 3 different packages
Applications
►► DC/DC SMPS startup circuits
►► Adjustable high voltage constant current sources
►► Industrial controls
►► Motor controls
►► Battery powered systems
►► Power supplies
►► Telecom applications
►► LED drivers
►► Automotive applications
General Description
The Supertex LR12 is a high voltage, low output current,
adjustable linear regulator. It has a wide operating input voltage
range of 13.2 - 100V. The output voltage can be adjusted from
1.20 - 88V, provided that the input voltage is at least 12V greater
than the output voltage. The output voltage can be adjusted
by means of two external resistors R₁ and R₂ as shown in the
typical application circuits. The LR12 regulates the voltage
difference between VOUT and ADJ pins to a nominal value of
1.20V. The 1.20V is amplified by the external resistor ratio R₁
and R₂. An internal constant bias current of typically 10µA is
connected to the ADJ pin. This increases V_OUT by a constant
voltage of 10µA times R₂.
The LR12 has current limiting and temperature limiting. The
output current limit is 100mA maximum and the minimum
temperature limit is 125°C. An output short circuit current will
therefore be limited to 100mA maximum. When the junction
temperature reaches its temperature limit, the output current
and/or output voltage will decrease to keep the junction
temperature from exceeding its temperature limit. For SMPS
start-up circuit applications, the LR12 turns off when an external
voltage greater than the output voltage of the LR12 is applied
to VOUT of the LR12. To maintain stability, a bypass capacitor
of 100nF or larger and a minimum DC output current of 500µA
are required.
LR12 Typical Application
V_IN
13.2 to 100V
C₁
*
VIN VOUT
ADJ
LR12
R₂
V_OUT
1.2 to 88V
R₁
C₂
R_LOAD
* Required for conditions where V_IN is less than V_OUT.
Doc.# DSFP-LR12
C080113
Supertex inc.
www.supertex.com