MAX1760(2001) 데이터 시트보기 (PDF) - Maxim Integrated
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MAX1760 Datasheet PDF : 12 Pages
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0.8A, Low-Noise, 1MHz,
Step-Up DC-DC Converter
Typical Operating Characteristics (continued)
(Circuit of Figure 2, VIN = 2.4V, VOUT = 3.3V, TA = +25°C, unless otherwise noted.)
NOISE SPECTRUM
16
12
8
4
0
0.1
1
10
FREQUENCY (MHz)
TURN-ON WAVEFORMS
NO SOFT-START COMPONENTS
A
B
C
OV
t = 2ms/div
A = ON, 5V/div
B = INPUT CURRENT, 500mA/div
C = VOUT, 2V/div
SOFT-START WAVEFORMS
RSS = 500kΩ, CSS = 0.1µF
A
B
C
0V
2.00ms/div
A = ON, 5V/div
B = INPUT CURRENT, 100mA/div
C = VOUT, 2V/div
Pin Description
PIN NAME
FUNCTION
N-Channel Current-Limit Control. For maximum current limit, connect to REF. To reduce current, supply a
1
ISET
voltage between REF and GND by means of a resistive voltage-divider. If soft-start is desired, connect a
capacitor from ISET to GND. When ON = high, or VREF <80% of nominal value, an on-chip 100kΩ switched
resistor discharges this pin to GND.
2
REF
1.250V Voltage Reference Bypass. Connect a 0.22µF ceramic bypass capacitor to GND. Up to 50µA of
external load current is allowed.
3
GND
Ground. Connect to PGND with short trace.
4
FB
DC-DC Converter Feedback Input. To set fixed output voltage of +3.3V, connect FB to ground. For
adjustable output of 2.5V to 5.5V, connect to a resistive divider from OUT to GND. FB set point = 1.24V.
5
OUT
IC Power, Supplied from the Output. Bypass to GND with a 0.68µF ceramic capacitor, and connect to POUT
with a series 4.7Ω resistor (Figure 2).
Clock Input for the DC-DC Converter. Also serves to program operating mode of switcher as follows:
CLK/SEL = LO: Normal operation—operates at a fixed frequency, automatically switching to low-power
6
CLK/SEL
mode if load is minimized.
CLK/SEL = HI: Forced PWM mode—operates in low-noise, constant-frequency mode at all loads.
CLK/SEL = Clocked: Forced PWM mode with the internal oscillator synchronized to CLK in 500kHz to
1200kHz range.
7
PGND Source of N-Channel Power MOSFET Switch
8
LX
Inductor Connection
9
POUT Power Output. P-channel synchronous-rectifier source.
10
ON
Shutdown Control Input. When ON = high, the IC is in shutdown. Connect ON to GND for normal operation.
6 _______________________________________________________________________________________
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