LM217L STMicroelectronics, LM217L Datasheet - Page 9

• Manufacturer Part Number: LM217L
• Description: Low current 1.2 to 37 V adjustable voltage regulator
• Manufacturer: STMicroelectronics

Specifications of LM217L

• Output Voltage Range: 1.2 to 37V

LM217L/LM317L
Application information
6
Application information
The LM317L provides an internal reference voltage of 1.25V between the output and
adjustments terminals. This is used to set a constant current flow across an external resistor
divider (see
Figure
4.), giving an output voltage V
of:
O
V
= V
(1 + R
/R
) + I
R
O
REF
2
1
ADJ
2
The device was designed to minimize the term I
(100µA max) and to maintain it very
ADJ
constant with line and load changes. Usually, the error term I
× R
can be neglected. To
ADJ
2
obtain the previous requirement, all the regulator quiescent current is returned to the output
terminal, imposing a minimum load current condition. If the load is insufficient, the output
voltage will rise.
Since the LM317L is a floating regulator and "sees" only the input-to-output differential
voltage, supplies of very high voltage with respect to ground can be regulated as long as the
maximum input-to-output differential is not exceeded. Furthermore, programmable regulator
are easily obtainable and, by connecting a fixed resistor between the adjustment and output,
the device can be used as a precision current regulator. In order to optimize the load
regulation, the current set resistor R
(see
Figure
4.) should be tied as close as possible to
1
the regulator, while the ground terminal of R
should be near the ground of the load to
2
provide remote ground sensing.
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