Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - power management - special purpose 40 µA TDFN 8 EP (3x3)

General Description

The MAX1946 single current-limited switch with auto-

reset 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 shut-

down. 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 reacti-

vates upon removal of the shorted condition.

The MAX1946 provides several safety features to pro-

tect the USB port. Built-in thermal-overload protection

turns off the switch when the die temperature exceeds

+160°C. Accurate internal current-limiting circuitry pro-

tects the input supply against both overload and short-

circuit conditions. An open-drain fault signal, (FAULT),

notifies the microprocessor (µP) when a thermal over-

load, 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 fault-

blanking 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

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

PART TEMP RANGE

PIN-

PACKAGE

TOP MARK

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

SEL

2GND

TDFN

TOP VIEW

OUT 3

OUT

MAX1946

1FAULT

Pin Configuration

OUT

ACTIVE HIGH

ACTIVE LOW

SELECTABLE

OUT

SEL

FAULT

INPUT

2.7V TO 5.5V

GND

MAX1946

Typical Operating Circuit

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

EP = Exposed paddle.

Summary of content (13 pages)

PAGE 1
9-2550; Rev 3; 2/10 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.
PAGE 2
MAX1946 Single USB Switch with Autoreset and Fault Blanking in Tiny TDFN ABSOLUTE MAXIMUM RATINGS IN, ON, OUT, SEL to GND........................................-0.3V to +6V FAULT to GND .............................................-0.3V to (VIN + 0.3V) IN to OUT..................................................................-0.3V to +6V OUT Continuous Switch Current (internally limited)..............1.3A FAULT DC Current ..............................................................
PAGE 3
Single USB Switch with Autoreset and Fault Blanking in Tiny TDFN (VIN = 5V, CIN = 0.1µF, COUT = 1µF, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note1) PARAMETER SYMBOL ON, SEL Input High Level VIH ON, SEL Input Low Level VIL ON, SEL Input Leakage Current FAULT Output Low Voltage CONDITIONS 1.6 VIN = 4V to 5.5V 2 TYP MAX UNITS V VIN = 2.7V to 4V 0.6 VIN = 4V to 5.5V 0.8 VON, VSEL = 0 or VIN, TA = +25°C VOL MIN VIN = 2.7V to 4V -1 ISINK = 1mA, VIN = 2.
PAGE 4
ELECTRICAL CHARACTERISTICS (continued) (VIN = 5V, CIN = 0.1µF, COUT = 1µF, TA = -40°C to +85°C, unless otherwise noted.) (Note1) PARAMETER SYMBOL Turn-Off Delay tOFF ON, SEL Input High Level VIH ON, SEL Input Low Level FAULT Output Low Voltage CONDITIONS MIN TYP ROUT = 10Ω, time from ON to 90% of VOUT, does not include fall time VIN = 2.7V to 4V 1.6 VIN = 4V to 5.5V 2 VIL UNITS 2 ms V 0.6 VIN = 4V to 5.5V VON, VSEL = 0 or VIN VOL MAX V VIN = 2.
PAGE 5
Single USB Switch with Autoreset and Fault Blanking in Tiny TDFN NORMALIZED ON-RESISTANCE vs. TEMPERATURE 10 1 0.1 1.0 0.9 0.8 0.7 0.01 10 35 60 1080 VIN = 5.5V VIN = 5.0V 1070 1060 1050 VIN = 2.7V 1040 1030 -40 85 -15 10 35 60 85 -40 -15 10 35 60 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) TURN-ON TIME vs. TEMPERATURE (tON + tRISE) TURN-OFF TIME vs. TEMPERATURE (tOFF + tFALL) FAULT-BLANKING TIME vs. TEMPERATURE 3.0 VIN = 2.7V 2.5 VIN = 5V 2.0 3.5 VIN = 5.5V 1.
PAGE 6
MAX1946 Single USB Switch with Autoreset and Fault Blanking in Tiny TDFN Typical Operating Characteristics (continued) (Circuit of Figure 2, VIN = 5V, CIN = 0.1µF, COUT = 1µF, ON = SEL, TA = +25°C, unless otherwise noted.) OVERLOAD RESPONSE INTO 2.5Ω (EXPANDED TIME SCALE) OVERLOAD RESPONSE INTO 2.
PAGE 7
Single USB Switch with Autoreset and Fault Blanking in Tiny TDFN SWITCH TURN-ON TIME (tON + tRISE) SWITCH TURN-OFF TIME (tOFF + tFALL) MAX1946 toc17 MAX1946 toc18 COUT = 1µF ROUT = 10Ω COUT = 1µF ROUT = 10Ω A 0 A 0 B 0 B 0 1ms/div 1ms/div A: VON, 2V/div B: VOUT, 2V/div A: VON, 2V/div B: VOUT, 2V/div STARTUP WAVEFORMS COUT = 1µF COUT = 1µF ROUT = 10Ω STARTUP WAVEFORMS COUT = 330µF MAX1946 toc19 COUT = 330µF ROUT = 10Ω MAX1946 toc20 0 A B 0 B 0 C 0 C 0 A D 0 D 0 1ms/div
PAGE 8
MAX1946 Single USB Switch with Autoreset and Fault Blanking in Tiny TDFN Typical Operating Characteristics (continued) (Circuit of Figure 2, VIN = 5V, CIN = 0.1µF, COUT = 1µF, ON = SEL, TA = +25°C, unless otherwise noted.
PAGE 9
Single USB Switch with Autoreset and Fault Blanking in Tiny TDFN MAX1946 IN ON CHARGE PUMP SEL IN FAULT MAX1946 ILIM OUT THERMAL SHUTDOWN 25mA FAULT LOGIC 20ms TIMERS OSC 25kHz UVLO BIAS REF GND Figure 1. Functional Diagram An internal micropower charge pump generates a highside supply that drives the gate of an internal 75mΩ NMOS switch. On/Off Control and Undervoltage Lockout (UVLO) SEL sets the active polarity of the logic input of the MAX1946.
PAGE 10
MAX1946 Single USB Switch with Autoreset and Fault Blanking in Tiny TDFN Fault Indicator The MAX1946 provides an open-drain fault output, FAULT. Connect FAULT to IN through a 100kΩ pullup resistor for most applications. FAULT asserts low when any of the following conditions occur: • The input voltage is below the UVLO threshold. • The switch junction temperature exceeds the +160°C thermal-shutdown temperature limit. • The switch is in current-limit or short-circuit currentlimit mode for more than 20ms.
PAGE 11
Single USB Switch with Autoreset and Fault Blanking in Tiny TDFN IN 100kΩ FAULT IN 0.1µF OFF ON MAX1946 OUT ON OUT SEL 1µF GND *USB APPLICATIONS MAY REQUIRE ADDITIONAL BULK CAPACITANCE Figure 2. Typical Application Circuit Output Capacitor Bypass OUT to GND with a 1µF ceramic capacitor for local decoupling. Additional bulk capacitance (up to 470µF) reduces output-voltage transients under dynamic load conditions.
PAGE 12
MAX1946 Single USB Switch with Autoreset and Fault Blanking in Tiny TDFN Package Information Chip Information PROCESS: BiCMOS 12 For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
PAGE 13
Single USB Switch with Autoreset and Fault Blanking in Tiny TDFN REVISION NUMBER REVISION DATE 3 2/10 DESCRIPTION Removed UL Certification Pending bullet from Features section PAGES CHANGED 1 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.