LTC1261C Ver la hoja de datos (PDF) - Linear Technology
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LTC1261C Datasheet PDF : 18 Pages
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LTC1261
APPLICATIONS INFORMATION
Table 2. Output Voltages Using the Internal Resistor Divider
PIN CONNECTIONS
OUTPUT VOLTAGE
ADJ to RADJ
–5V
ADJ to RADJ, R0 to GND
–4.5V
ADJ to RADJ, R1 to R0
–4V
ADJ to RADJ, R1 to GND
–3.5V
ADJ to R1
–1.77V
ADJ to R0
–1.38V
ADJ to GND
–1.24V
There are some oddball output voltages available by con-
necting ADJ to R0 or R1 and shorting out some of the
internal resistors. If one of these combinations gives you
the output voltage you want, by all means use it!
The internal resistor values are the same for the fixed
output versions of the LTC1261 as they are for the
adjustable. The output voltage can be trimmed, if desired,
by connecting external resistance from the COMP pin to
OUT or ground to alter the divider ratio. As in the adjustable
parts, the absolute value of the internal resistors may vary
significantly from unit to unit. As a result, the further the
trim shifts the output voltage the less accurate the output
voltage will be. If a precise output voltage other than one
of the available fixed voltages is required, it is better to
use an adjustable LTC1261 and use precision external
resistors. The internal reference is trimmed at the factory
to within 3.5% of 1.24V; with 1% external resistors the
output will be within 5.5% of the nominal value, even
under worst case conditions.
The LTC1261 can be internally configured with nonstan-
dard fixed output voltages. Contact the Linear Technology
Marketing Department for details.
TYPICAL APPLICATIONS
3.3V Input, –4.5V Output GaAs FET Bias Generator
VBAT
3.3V
1µF
SHUTDOWN
0.1µF
0.1µF
14
2
C1+
VCC
SHDN
13
3 C1–
REG 12
4
LTC1261
C2+
OUT
11
5 C2–
ADJ 10
NC 8 R1
R0
7
RADJ 9
GND
6
100pF
P-CHANNEL
POWER SWITCH
10k
–4.5V BIAS
3.3µF
GaAs
TRANSMITTER
LTC1261 • TA03
For more information www.linear.com/LTC1261
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