MAX1946ETA(2003) 查看數據表（PDF） - Maxim Integrated
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MAX1946ETA
(Rev.:2003)
(Rev.:2003)
Maxim Integrated
MAX1946ETA Datasheet PDF : 13 Pages
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Single USB Switch with Autoreset and
Fault Blanking in Tiny QFN
Typical Operating Characteristics (continued)
(Circuit of Figure 2, VIN = 5V, CIN = 0.1µF, COUT = 1µF, ON = SEL, TA = +25°C, unless otherwise noted.)
STARTUP WAVEFORMS
COUT = 100µF
MAX1946 toc21
UVLO RESPONSE
MAX1946 toc22
COUT = 100µF
A
ROUT = 10Ω
B
C
D
1ms/div
A: VOUT, 5V/div
B: VFAULT, 5V/div
C: VOUT, 2V/div
D: IOUT, 500mA/div
0
A
0
0
B
0
0
C
0
0
10ms/div
A: VIN, 2V/div
B: VOUT, 2V/div
C: VFAULT, 2V/div
Pin Description
PIN
NAME
FUNCTION
1
FAULT
Fault-Indicator Output Switch. Open-drain output asserts low when switch enters thermal shutdown,
undervoltage lockout, or a sustained (>20ms) current-limit or short-circuit condition.
2
GND
Ground
Switch Power Output. Connect OUT pins together at the device and bypass with a 1µF ceramic
3, 4
OUT
capacitor. Load conditions may require additional bulk capacitance. When disabled, OUT goes into
a high-impedance state.
Switch Power Input. Connect IN pins together at the device and bypass with a 0.1µF ceramic
5, 6
IN
capacitor to GND. Input conditions may require additional bulk capacitance to prevent pulling the
input supply down.
7
ON
ON/OFF Control Input. The active polarity of ON is set by SEL. Connect SEL high to make ON active
high. Connect SEL to GND to make ON active low.
8
SEL
Logic Input Polarity Select. SEL sets the active polarity of the ON input. Connect SEL high to make
ON active high. Connect SEL to GND to make ON active low.
Detailed Description
The MAX1946 includes output current limiting, short-cir-
cuit protection, thermal shutdown, an enable input, and
fault indicator (see the Functional Diagram). A logic
input at SEL sets the active polarity of the enable input.
The fault indicator notifies the system when the current-
limit, short-circuit, undervoltage lockout, or thermal-
shutdown threshold is exceeded.
The MAX1946 operates from a 2.7V to 5.5V input
supply and supplies a minimum output current of 740mA.
A built-in current limit of 1.1A limits the output current in
the event of an overload condition. A built-in short-circuit
detection circuit pulses the output current if the output
voltage falls below 1V. This lowers RMS output current
and reduces power dissipation during continuous short
conditions.
An internal micropower charge pump generates a high-
side supply that drives the gate of an internal 75mΩ
NMOS switch.
8 _______________________________________________________________________________________
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