19-2550; Rev 2; 3/07
Single USB Switch with Autoreset and
Fault Blanking in Tiny TDFN
The MAX1946 single current-limited switch with autoreset supplies a guaranteed 500mA load in accordance
with USB specifications. The MAX1946 operates from a
2.7V to 5.5V input supply and consumes only 40µA of
quiescent current when operating and only 3µA in shutdown. Selectable active-high/active-low control logic
and shutdown control provide additional flexibility. An
autoreset feature latches the switch off in the event of a
short circuit, saving system power. The switch reactivates upon removal of the shorted condition.
The MAX1946 provides several safety features to protect the USB port. Built-in thermal-overload protection
turns off the switch when the die temperature exceeds
+160°C. Accurate internal current-limiting circuitry protects the input supply against both overload and shortcircuit conditions. An open-drain fault signal, (FAULT),
notifies the microprocessor (µP) when a thermal overload, current-limit, undervoltage lockout (UVLO), or
short-circuit fault occurs. A 20ms fault-blanking feature
enables the circuit to ignore momentary faults, such as
those caused when hot-swapping a capacitive load,
preventing false alarms to the host system. The faultblanking feature prevents fault signals from being
issued when the device powers up the load.
The MAX1946 is available in a space-saving 8-pin
TDFN package and operates over the extended (-40°C
to +85°C) temperature range.
Applications
Features
♦ Single USB Switch in 3mm x 3mm Package
♦ Autoreset Feature Saves System Power
♦ Guaranteed 500mA Load Current
♦ Built-In 20ms Fault-Blanking Circuitry
♦ Active-High or Active-Low Control Logic
♦ Fully Compliant to USB Specifications
♦ 2.7V to 5.5V Input Voltage Range
♦ Fault-Indicator Output
♦ Thermal-Overload Protection
♦ UL Certification Pending
Ordering Information
PART
TEMP
RANGE
PINPACKAGE
TOP
MARK
PKG
CODE
MAX1946ETA+
-40°C to
+85°C
8 TDFN-EP*
3mm x 3mm
ACQ
T833-1
+Denotes a lead-free package.
*EP = Exposed paddle.
USB Ports and USB Hubs
Notebook and Desktop Computers
PDAs and Palmtop Computers
Digital Cameras
Docking Stations
Typical Operating Circuit
Pin Configuration
INPUT
2.7V TO 5.5V
TOP VIEW
+
GND 2
IN
8 SEL
FAULT 1
MAX1946
FAULT
IN
7 ON
OUT 3
6 IN
OUT 4
5 IN
ACTIVE HIGH
ACTIVE LOW
SELECTABLE
ON
MAX1946
OUT
OUT
SEL
GND
TDFN
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1
MAX1946
General Description