Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsDiodesMAX9940AXK+T

General Description

The MAX9940 signal-line overvoltage protector for low-

voltage digital communication ports provides protection

against high-voltage faults and ESD strikes. The

MAX9940 is especially useful for sensitive communica-

tion protocols such as Maxim 1-Wire

that cannot

afford standard means of fault protection, such as large

series resistors or large line capacitances.

The MAX9940 operates from a single supply voltage of

+2.2V to +5.5V and consumes only 13µA of quiescent

supply current. The EXT port is protected up to 28V.

The device features a reaction time of 60ns for fast

action during fault conditions and operates over the

-40°C to +125°C automotive temperature range.

Applications

Notebook Computers

Portable Devices

Industrial Equipment

Features

♦ 28V Protection on EXT

♦ Extended ESD Protection

±4kV IEC 61000-4 Contact on EXT

♦ +2.2V to +5.5V Supply Voltage Range

♦ 13µA Quiescent Supply Current

♦ 60ns Fault Reaction Time

♦ Small, 5-Pin SC70

♦ -40°C to +125°C Temperature Range

MAX9940

Signal-Line Overvoltage Protector

for Low-Voltage Devices

________________________________________________________________

Maxim Integrated Products

19-4168; Rev 0; 2/09

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.

NOTEBOOK

ADAPTER

MICROCONTROLLER

EXT

GND

INT

1-Wire

DEVICE

2kΩ

20V

PROTECTION

CIRCUIT

ENABLE

DATA

NOTEBOOK

BATTERY

CHARGER

LOAD

= 3.3V

MAX9940

Block Diagram/Typical Application Circuit

Ordering Information

PART TEMP RANGE

PIN-

PACKAGE

TOP

MARK

MAX9940AXK+ -40°C to +125°C 5 SC70 ATC

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

1-Wire is a registered trademark of Maxim Integrated Products, Inc.

Summary of content (9 pages)

PAGE 1
9-4168; Rev 0; 2/09 Signal-Line Overvoltage Protector for Low-Voltage Devices The MAX9940 signal-line overvoltage protector for lowvoltage digital communication ports provides protection against high-voltage faults and ESD strikes. The MAX9940 is especially useful for sensitive communication protocols such as Maxim 1-Wire ® that cannot afford standard means of fault protection, such as large series resistors or large line capacitances. The MAX9940 operates from a single supply voltage of +2.2V to +5.
PAGE 2
MAX9940 Signal-Line Overvoltage Protector for Low-Voltage Devices ABSOLUTE MAXIMUM RATINGS (All voltages with respect to GND.) VCC ...........................................................................-0.3V to +6V INT ............................................................................-0.3V to +6V EXT .........................................................................-0.3V to +30V Continuous Input Current into Any Terminal.....................
PAGE 3
Signal-Line Overvoltage Protector for Low-Voltage Devices 40 VCC = 3.3V VCC = 5.5V 20 TA = +125°C TA = +85°C 40 30 20 TA = +25°C 10 300 TURN-ON/TURN-OFF TIME (ns) ON-RESISTANCE (Ω) VCC = 2.5V 50 MAX9940 toc02 50 ON-RESISTANCE (Ω) 60 MAX9940 toc01 60 30 TURN-ON/TURN-OFF TIME vs. TEMPERATURE ON-RESISTANCE vs. VCM TURN-ON 250 200 150 TURN-OFF 100 EXT = 0 TO 10V SQUARE WAVE RPULLUP = 200Ω 50 10 TA = -40°C 3 4 5 0 6 0.5 1.0 1.5 2.0 2.5 3.0 VCM (V) TURN-ON/TURN-OFF TIME vs.
PAGE 4
Typical Operating Characteristics (continued) (VCC = +3.3V, RINT_PULLUP = 2kΩ to VDD, VDD = 3.3V, TA = TMIN to TMAX, unless otherwise noted.
PAGE 5
Signal-Line Overvoltage Protector for Low-Voltage Devices PIN NAME 1 VCC FUNCTION 2 GND Ground 3 N.C. No Connection. Not internally connected. 4 INT Microcontroller I/O Port. Connection to a microcontroller data port. 5 EXT External Connector Port. Connection to a 1-Wire device. Power Supply. Can be connected to a microcontroller enable input.
PAGE 6
MAX9940 Signal-Line Overvoltage Protector for Low-Voltage Devices VDD = 3.3V ENABLE VCC MICROCONTROLLER RP 2kΩ MAX9940 1-Wire DEVICE DATA Rx INT Rx EXT GND Tx Tx Figure 1. Recommended Scheme for Battery-Operated Devices that Need to Shut Down the MAX9940 and Prevent Power Draw During Short to GND Faults In all three schemes, the MAX9940 protects the microcontroller from both DC fault voltages above VCC and ESD strikes on EXT.
PAGE 7
Signal-Line Overvoltage Protector for Low-Voltage Devices MAX9940 VDD = 3.3V ENABLE VCC MICROCONTROLLER RP 2kΩ MAX9940 1-Wire DEVICE DATA Rx INT Rx EXT GND Tx Tx Figure 2. Recommended Scheme for Applications that Require the MAX9940 to be Put into Shutdown VDD = 3.3V VCC MICROCONTROLLER RP 2kΩ MAX9940 1-Wire DEVICE DATA Rx Rx INT EXT GND Tx Tx Figure 3.
PAGE 8
Signal-Line Overvoltage Protector for Low-Voltage Devices MAX9940 Pin Configuration Chip Information PROCESS: BiCMOS TOP VIEW + VCC 1 GND 2 5 EXT 4 INT MAX9940 N.C.
PAGE 9
Signal-Line Overvoltage Protector for Low-Voltage Devices PACKAGE CODE DOCUMENT NO. 5 SC70 X5-1 21-0076 SC70, 5L.EPS PACKAGE TYPE PACKAGE OUTLINE, 5L SC70 21-0076 E 1 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.