Datasheet
MAX1946
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.
Single USB Switch with Autoreset and
Fault Blanking in Tiny TDFN
8 _______________________________________________________________________________________
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
3, 4 OUT
Switch Power Output. Connect OUT pins together at the device and bypass with a 1µF ceramic
capacitor. Load conditions may require additional bulk capacitance. When disabled, OUT goes into
a high-impedance state.
5, 6 IN
Switch Power Input. Connect IN pins together at the device and bypass with a 0.1µF ceramic
capacitor to GND. Input conditions may require additional bulk capacitance to prevent pulling the
input supply down.
7ON
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.
—EP
Exposed Metal Paddle. This paddle is internally connected to GND through a soft connect. For
enhanced thermal dissipation, connect EP to a large ground plane. Do not use EP as a sole ground
connection.
Pin Description
STARTUP WAVEFORMS
C
OUT
= 100µF
MAX1946 toc21
1ms/div
A
D
C
0
0
0
0
B
C
OUT
= 100µF
R
OUT
= 10Ω
A: V
OUT
,
5V/div
B: V
FAULT
,
5V/div
C: V
OUT
,
2V/div
D: I
OUT
,
500mA/div
Typical Operating Characteristics (continued)
(Circuit of Figure 2, V
IN
= 5V, C
IN
= 0.1µF, C
OUT
= 1µF, ON = SEL, T
A
= +25°C, unless otherwise noted.)
UVLO RESPONSE
MAX1946 toc22
10ms/div
A
B
0
0
0
C
A: V
IN
,
2V/div
B: V
OUT
,
2V/div
C: V
FAULT
,
2V/div