MAXIM MAX1946 Technical data

General Description

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
(3mm x 3mm) TDFN package and operates over the
extended (-40°C to +85°C) temperature range.

Applications

USB Ports and USB Hubs

Notebook and Desktop Computers

PDAs and Palmtop Computers

Digital Cameras

Docking Stations

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

MAX1946

Single USB Switch with Autoreset and

Fault Blanking in Tiny TDFN

________________________________________________________________

Maxim Integrated Products

1

19-2550; Rev 3; 2/10

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.

Ordering Information

Pin Configuration

IN

IN

OUT

ACTIVE HIGH

ACTIVE LOW
SELECTABLE

OUT

ON

SEL

FAULT

INPUT

2.7V TO 5.5V

GND

MAX1946

Typical Operating Circuit

+

Denotes a lead(Pb)-free/RoHS-compliant package.

*

EP = Exposed paddle.

PART TEMP RANGE

MAX1946ETA+ -40°C to +85°C 8 TDFN-EP* ACQ

PIN-

PACKAGE

TOP MARK

TOP VIEW

+

SEL

1FAULT

MAX1946

2GND

OUT 3

OUT

4

TDFN

8

ON

7

IN

6

IN

5

MAX1946

Single USB Switch with Autoreset and
Fault Blanking in Tiny TDFN

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

IN, ON, OUT, SEL to GND........................................-0.3V to +6V

FAULT to GND.............................................-0.3V to (V

IN

+ 0.3V)

IN to OUT..................................................................-0.3V to +6V

OUT Continuous Switch Current (internally limited)..............1.3A

FAULT DC Current ..............................................................10mA

Continuous Power Dissipation (T

A

= +70°C)
Exposed Pad Must be Soldered to PC Board

8-Pin TDFN (derate 23.8mW/°C above +70°C) .........1905mW

Operating Temperature Range ...........................-40°C to +85°C

Junction Temperature......................................................+150°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

ELECTRICAL CHARACTERISTICS

(VIN= 5V, CIN= 0.1µF, C

OUT

= 1µF, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note1)

PARAMETER

SYM B O L

CONDITIONS

MIN

TYP

MAX

UNITS

Supply Voltage Range V

IN

2.7 5.5 V

VIN = 5, TA = +25°C 75 90

VIN = 5V 110Switch On-Resistance R

ON

VIN = 3.3V 125

mΩ

Standby Supply Current Switch disabled 3 10 µA

Quiescent Supply Current I

IN

Switch enabled, I

OUT

= 0 40 60 µA

Switch disabled, V

OUT

= 0, TA = +25°C

1

OUT Off-Leakage Current I

LKG

Switch disabled, V

OUT

= 0, TA = +85°C 0.2

µA

Undervoltage Lockout Threshold

V

ULVO

Rising edge, 3% hysteresis 2.3 2.5 2.7 V

Continuous Load Current

mA

Continuous Current Limit I

LIM

V

IN_

- V

OUT

= 0.5V

1.1

A

0.8 1.2 1.6 A

PK

Short-Circuit Current Limit I

SC

V

OUT

= 0 (I

OUT

pulsing)

Short-Circuit Detect Threshold (Note 2) 1 V

Continuous Current-Limit
Blanking Timeout Period

From continuous current-limit condition to
FAULT asserted

10 20 35 ms

Short-Circuit Blanking Timeout
Period

From short-circuit current-limit condition to
FAULT asserted

7.5 18

ms

Turn-On Delay t

ON

R

OUT

= 10Ω, time from ON to 10% of V

OUT

,

does not include rise time

0.6

ms

Output Rise Time t

RISE

R

OUT

= 10Ω, from 10% to 90% of V

OUT

1.2 ms

Turn-Off Delay t

OFF

R

OUT

= 10Ω, time from ON to 90% of V

OUT

,

does not include fall time

0.8 2 ms

Output Fall Time t

FALL

R

OUT

= 10Ω, from 90% to 10% of V

OUT

3ms

Thermal-Shutdown Threshold 15oC hysteresis

°C

0.01

500

0.74

0.25

0.35 A

160

1.20

RMS

35.0

1.50

MAX1946

Single USB Switch with Autoreset and

Fault Blanking in Tiny TDFN

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VIN= 5V, CIN= 0.1µF, C

OUT

= 1µF, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note1)

PARAMETER

CONDITIONS

UNITS

VIN = 2.7V to 4V 1.6

ON, SEL Input High Level V

IH

VIN = 4V to 5.5V 2

V

VIN = 2.7V to 4V 0.6

ON, SEL Input Low Level V

IL

VIN = 4V to 5.5V 0.8

V

ON, SEL Input Leakage Current VON, V

SEL

= 0 or VIN, TA = +25°C -1 +1 µA

FAULT Output Low Voltage V

OL

I

SINK

= 1mA, V

IN

= 2.7V 0.5 V

FAULT Output High Leakage
Current

V

IN

= V

FAULT

= 5.5V 1 µA

OUT Output Current Autoreset
Mode

In latched off state, V

OUT

= 0 102545mA

OUT Autoreset Threshold In latched off state, V

OUT

rising 0.4 0.5 0.6 V

OUT Autoreset Blanking Time In latched off state, V

OUT

> 0.5V 10 20 35 ms

ELECTRICAL CHARACTERISTICS

(VIN= 5V, CIN= 0.1µF, C

OUT

= 1µF, TA= -40°C to +85°C, unless otherwise noted.) (Note1)

PARAMETER

CONDITIONS

Supply Voltage Range V

IN

2.7 5.5 V

VIN = 5, TA = +25°C 90

VIN = 5V 110Switch On-Resistance R

ON

VIN = 3.3V 125

mΩ

Standby Supply Current Switch disabled 10 µA

Quiescent Supply Current I

IN

Switch enabled, I

OUT

= 0 60 µA

OUT Off-Leakage Current I

LKG

1µA

Undervoltage Lockout Threshold

V

ULVO

Rising edge, 3% hysteresis 2.3 2.7 V

Continuous Load Current

mA

Continuous Current Limit I

LIM

V

IN_

- V

OUT

= 0.5V 0.6 1.3 A

Short-Circuit Current Limit I

SC

V

OUT

= 0 (I

OUT

pulsing) 0.8 1.6 A

PK

Continuous Current-Limit
Blanking Timeout Period

From continuous current-limit condition to
FAULT asserted

10 35 ms

Short-Circuit Blanking Timeout
Period

From short-circuit current-limit condition to
FAULT asserted

7.5

ms

Turn-On Delay t

ON

R

OUT

= 10Ω. Time from ON to 10% of V

OUT

.

Does not include rise time.

ms

SYM B O L

SYM B O L

MIN TYP MAX

MIN TYP MAX UNITS

S w i tch d i sabl ed , V

= 0, TA = - 40°C to + 25°C

OU T

500

0.25 1.50

35.0

MAX1946

Single USB Switch with Autoreset and
Fault Blanking in Tiny TDFN

4 _______________________________________________________________________________________

Note 1: All parts are 100% tested at TA= +25°C. Limits over the operating temperature range are guaranteed by design.
Note 2: Short-circuit detect threshold is the output voltage at which the device transitions from short-circuit current limit to continuous

current limit.

ELECTRICAL CHARACTERISTICS (continued)

(VIN= 5V, CIN= 0.1µF, C

OUT

= 1µF, TA= -40°C to +85°C, unless otherwise noted.) (Note1)

PARAMETER

CONDITIONS

UNITS

Turn-Off Delay t

OFF

R

OUT

= 10Ω, time from ON to 90% of V

OUT

,

does not include fall time

2ms

VIN = 2.7V to 4V 1.6 V

ON, SEL Input High Level V

IH

VIN = 4V to 5.5V 2 V

VIN = 2.7V to 4V 0.6 V

ON, SEL Input Low Level V

IL

VIN = 4V to 5.5V 0.8 V

ON, SEL Input Leakage Current VON, V

SEL

= 0 or V

IN

-1 +1 µA

FAULT Output Low Voltage V

OL

I

SINK

= 1mA, V

IN

= 2.7V 0.5 V

OUT Output Current Autoreset
Mode

In latched off state, V

OUT

= 0 10 45 mA

OUT Autoreset Threshold In latched off state, V

OUT

rising 0.4 0.6 V

OUT Autoreset Blanking Time In latched off state, V

OUT

> 0.5V 10 35 ms

QUIESCENT SUPPLY CURRENT

vs. INPUT VOLTAGE

MAX1946 toc01

INPUT VOLTAGE (V)

QUIESCENT SUPPLY CURRENT (µA)

5.04.54.03.53.02.52.01.51.00.50

10

20

30

40

50

0

5.5

V

SEL

= VON = GND

QUIESCENT SUPPLY CURRENT

vs. TEMPERATURE

MAX1946 toc02

TEMPERATURE (°C)

QUIESCENT SUPPLY CURRENT (µA)

603510-15

33

36

39

42

45

30

-40 85

V

SEL

= VON = GND

VIN = 5V

VIN = 5.5V

VIN = 2.7V

SHUTDOWN SUPPLY CURRENT

vs. TEMPERATURE

MAX1946 toc03

TEMPERATURE (°C)

SHUTDOWN SUPPLY CURRENT (µA)

6035-15 10

2.7

2.8

2.9

3.0

3.1

3.2

3.3

3.4

2.6

-40 85

ON = GND, V

SEL

= 5V

Typical Operating Characteristics

(Circuit of Figure 2, VIN= 5V, CIN= 0.1µF, C

OUT

= 1µF, ON = SEL, TA= +25°C, unless otherwise noted.)

SYM B O L

MIN TYP MAX