LTC1261L Ver la hoja de datos (PDF) - Linear Technology
Número de pieza
componentes Descripción
Fabricante
LTC1261L Datasheet PDF : 14 Pages
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TYPICAL PERFORMANCE CHARACTERISTICS
Oscillator Frequency
vs Temperature
725
TA = 25°C
700 VOUT = – 4V
VCC = 5V
675
650
625
600
575
550
525
–40 –25 –10 5 20 35 50 65 80 95
TEMPERATURE (°C)
1261L G10
Start-Up Time vs Supply Voltage
0.7
TA = 25°C
0.6 IOUT = 10mA
0.5
VOUT = – 4V
0.4
0.3
VOUT = – 2V
0.2
0.1
0
2.5
3.0 3.5 4.0 4.5
SUPPLY VOLTAGE (V)
5.0
1261L G11
LTC1261L
Output Short-Circuit Current
vs Temperature
160
140
120
VCC = 5.25V
100
VCC = 5V
80
60
VCC = 3V
40
20
VCC = 2.7V
0
– 40 – 25 –10 5 20 35 50 65 80 95
TEMPERATURE (°C)
1261L G12
PIN FUNCTIONS
VCC (Pin 1): Power Supply. This requires an input voltage
between 2.7V and 5.25V. VCC must be bypassed to ground
with at least a 1µF capacitor placed in close proximity to the
chip. See the Applications Information section for details.
C1+ (Pin 2): C1 Positive Input. Connect a 0.1µF capacitor
between C1+ and C1–.
C1– (Pin 3): C1 Negative Input. Connect a 0.1µF capacitor
from C1+ to C1–.
GND (Pin 4): Ground. Connect to a low impedance ground.
A ground plane will help to minimize regulation errors.
ADJ (COMP for Fixed Versions) (Pin 5): Output Adjust/
Compensation Pin. For adjustable parts this pin is used to
set the output voltage. The output voltage is divided down
with an external resistor divider and fed back to this pin
to set the regulated output voltage. Typically the resistor
string should draw ≥10µA from the output to minimize
errors due to the bias current at the adjust pin. Fixed output
voltage parts have the internal resistor string connected
to this pin inside the package. The pin can be used to
trim the output voltage if desired. It can also be used as
an optional feedback compensation pin to reduce output
ripple on both the adjustable and fixed output voltage
parts. See the Applications Information section for more
information on compensation and output ripple.
OUT (Pin 6): Negative Voltage Output. This pin must be
bypassed to ground with a 1µF or larger capacitor. The
value of the output capacitor and its ESR have a strong
effect on output ripple. See the Applications Information
section for more details.
REG (Pin 7): This is an open-drain output that pulls low
when the output voltage is within 5% of the set value. It
will sink 5mA to ground with a 5V supply. The external
circuitry must provide a pull-up or REG will not swing high.
The voltage at REG may exceed VCC and can be pulled up
to 6V above ground without damage.
SHDN (Pin 8): Shutdown. When this pin is at ground the
LTC1261L operates normally. An internal 5µA pull-down
keeps SHDN low if it is left floating. When SHDN is pulled
high, the LTC1261L enters shutdown mode. In shutdown,
the charge pump is disabled, the output collapses to 0V
and the quiescent current drops to 5µA typically.
1261lfa
5
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