LTC1779 データシートの表示（PDF） - Linear Technology
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LTC1779 Datasheet PDF : 12 Pages
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TYPICAL PERFOR A CE CHARACTERISTICS
Reference Voltage
vs Temperature
825
VIN = 4.2V
820
815
810
805
800
795
790
785
780
775
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
1779 G01
Shutdown Threshold
vs Temperature
600
VIN = 4.2V
560
520
480
440
400
360
320
280
240
200
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
1779 G04
Normalized Oscillator Frequency
vs Temperature
15
VIN = 4.2V
12
9
6
3
0
–3
–6
–9
–12
–15
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
1779 G02
RDS(ON) of Internal P-Channel FET
vs Input Voltage
1.85
1.70
ISSEWNS=E1–0=0mVAIN
1.55
1.40
1.25
TA = 125°C
1.10
0.95
TA = 25°C
0.80
0.65
TA = –55°C
0.50
0.35
2 3 4 5 6 7 8 9 10
INPUT VOLTAGE (V)
1779 G05
LTC1779
Undervoltage Lockout Trip
Voltage vs Temperature
2.20
VIN FALLING
2.16
2.12
2.08
2.04
2.00
1.96
1.92
1.88
1.84
1.80
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
1779 G03
RDS(ON) of Internal P-Channel FET
vs Temperature
1.85
1.70 SISEWNS=E1–0=0mVAIN
1.55
1.40
VIN = 2.4V
1.25
1.10
VIN = 4.2V
0.95
VIN = 6V
0.80
0.65
0.50
VIN = 9.8V
VIN = 8.4V
0.35
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
1779 G06
PI FU CTIO S
ITH/RUN (Pin 1): This pin performs two functions. It
serves as the error amplifier compensation point as well as
the run control input. The current comparator threshold
increases with this control voltage. Nominal voltage range
for this pin is 0.7V to 1.9V. Forcing this pin below 0.325V
causes the device to be shut down. In shutdown all
functions are disabled and the internal P-channel MOSFET
is turned off. The SW pin will be high impedance.
GND (Pin 2): Ground Pin.
VFB (Pin 3): Receives the feedback voltage from an exter-
nal resistive divider across the output.
SENSE– (Pin 4): The Negative Input to the Current Com-
parator. Can be connected to VIN for default minimum
peak current of 250mA. Connecting a resistor between
SENSE– and VIN specifies a lower peak current. (See
Applications Information for specifying resistor value.)
VIN (Pin 5): Supply Pin. Must be closely decoupled to GND
Pin 2.
SW (Pin 6): Switching Node and Drain of Internal
P-Channel Power MOSFET. Connects to external induc-
tor and catch diode.
3
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