MAX1760 Ver la hoja de datos (PDF) - Maxim Integrated
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MAX1760 Datasheet PDF : 14 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
TURN-ON WAVEFORMS
NO SOFT-START COMPONENTS
SOFT-START WAVEFORMS
RSS = 500kΩ, CSS = 0.1µF
A
A
12
8
B
B
4
0
0.1
1
10
FREQUENCY (MHz)
C
OV
t = 2ms/div
A = ON, 5V/div
B = INPUT CURRENT, 500mA/div
C = VOUT, 2V/div
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.
ON
MAX1760 Enable Input. When ON is low, the IC is on. Connect to GND for normal operation.
10
ON
MAX1760H Enable Input. When ON is high, the IC is on. Connect to OUT for normal operation.
—
EP
Exposed Paddle (TDFN Package Only). Internally connected to GND. Connect to a large ground plane to
maximize thermal dissipation. Do not use as sole ground connection.
6 _______________________________________________________________________________________
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