Rainbow Electronics MAX4981 User Manual

General Description

The MAX4978–MAX4981 overvoltage-protection devices
protect low-voltage systems against voltage faults up to
+28V and feature a low 85mΩ RONFET, an active cur­rent limiter, and lithium-ion battery overcharge protec­tion (MAX4980/MAX4981). These devices are used to
protect the charger input port on a portable device.

The overvoltage protector feature protects against volt­ages up to 28V with two different trip thresholds: 5.7V
(MAX4978/MAX4980/MAX4981) and 6.8V (MAX4979).
There is an undervoltage protector with two different trip
thresholds: 4.4V (MAX4978) and 2.63V (MAX4979/
MAX4980/MAX4981).

The overcurrent limiter and battery voltage monitor fea­tures provide a second layer of protection for a lithium­ion battery charger. The overcurrent limiter is available
in two different thresholds: 0.9A (MAX4978/MAX4979/
MAX4980) and 1.95A (MAX4981). Once current reach­es the threshold, it is held for a 20ms blanking time. If
the current is still at the limit after the blanking time, the
FET is turned off, and the device restarts the cycle after
160ms. The battery voltage monitor measures the volt­age of a lithium-ion battery and disables the FET if the
battery voltage reaches 4.4V (MAX4980/MAX4981).

The MAX4978–MAX4981 are available in a small 8-pin
TDFN (2mm x 3mm) package and are specified over
the extended -40°C to +85°C temperature range.

Applications

Features

o Input Voltage Protection Up to +28V
o Integrated nFET Switch, 85mΩ (typ)
o Preset Overvoltage Protection Trip Level

5.7V (typ) (MAX4978/MAX4980/MAX4981)

6.8V (typ) (MAX4979)

o Low-Current Undervoltage Lockout Mode
o Overcurrent Protection
o Internal 160ms (typ) Startup Delay
o Thermal-Shutdown Protection
o Battery Overcharge Protection

(MAX4980/MAX4981)

o Startup Debounce Time Indicator

(MAX4978/MAX4979)

o Small, 8-Pin (2mm x 3mm) TDFN Package

MAX4978–MAX4981

Overvoltage Protector with

Active Current Limit

________________________________________________________________

Maxim Integrated Products

1

Ordering Information/Selector Guide

19-4137; Rev 0; 5/08

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.

Note: All devices specified over the -40°C to +85°C operating temperature range.

+

Denotes a lead-free package.

*

EP = Exposed pad.

**

Future product—contact factory for availability.

(mA)

Pin Configuration

134

865

OUT

MAX4978
MAX4979
MAX4980
MAX4981

2

7

IN

(BAT) IS FOR MAX4980/MAX4981 ONLY.
*EP = EXPOSED PAD. CONNECT EP TO GND.

I.C.

TDFN-EP

TOP VIEW

I.C. GNDI.C.

*EP

EN

SDT(BAT)

Typical Application Circuit appears at end of data sheet.

Cell Phones
MP3 Players
Digital Still Cameras

PDAs and Palmtop
Devices

PART PIN-PACKAGE

MAX4978ETA+

MAX4979ETA+**

MAX4980ETA+

MAX4981ETA+

CURRENT

LIMIT

8 TDFN-EP*

8 TDFN-EP*

8 TDFN-EP*

8 TDFN-EP*

900 No 4.4 5.7 AAK T823-1

900 No 2.63 6.8 AAL T823-1

900 Yes 2.63 5.7 AAM T823-1

1950 Yes 2.63 5.7 AAN T823-1

BATTERY
MONITOR

UVLO

(V)

OVLO

(V)

TOP

MARK

PKG

CODE

MAX4978–MAX4981

Overvoltage Protector with
Active Current Limit

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VIN= 5.0V, VEN= 0V, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 2)

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.

(Voltages referenced to GND.)

IN, SDT ................................................................. -0.3V to +30V

OUT ........................................................................... -0.3V to IN

EN, BAT .................................................................. -0.3V to +6V

SDT Continuous Current ................................................. ±50mA

Continuous Power Dissipation (T

A

= +70°C)
8-Pin 2mm x 3mm TDFN (derate 16.7mW/°C

above +70°C) ........................................................... 1333mW

Junction-to-Case Thermal Resistance (

θ

JC

) (Note 1)

8-Pin 2mm x 3mm TDFN ......................................... 10.8°C/W

Junction-to-Ambient Thermal Resistance (

θ

JA

) (Note 1)

8-Pin 2mm x 3mm TDFN ............................................ 60°C/W

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

Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a 4-layer

board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial

.

Input Voltage Range V

Input Supply Current I

UVLO Supply Current I

Shutdown Supply Current I

IN Undervoltage Lockout V

IN Undervoltage Lockout
Hysteresis

IN Overvoltage Lockout V

IN Overvoltage Lockout Hysteresis 1%

BAT Overvoltage Trip Level V

BAT Overvoltage Hysteresis MAX4980/MAX4981 1 %

BAT Input Leakage Current I

Switch On-Resistance R

Overcurrent Protection Threshold I

Thermal Shutdown T

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

IN

I

IN

UVLOVIN

SHDNV EN

UVLO

OVLO

BOTL

LKGB

ONIOUT

LIM

SHDNTA

OUT

MAX4978

MAX4979/MAX4980/
MAX4981

MAX4978/MAX4980/
MAX4981

MAX4979

MAX4980/MAX4981, V

MAX4980/MAX4981, V

MAX4978, MAX4979,
MAX4980

MAX4981

< I

LIM_MIN

= 2.3V 35 60 µA

= 5V 15 23 µA

= 100mA 85 160 mΩ

rising 160 °C

2.3 28 V

VIN falling 4.2

rising 4.3 4.4 4.5

V

IN

VIN falling 2.5

V

rising 2.56 2.63 2.70

IN

VIN falling 5.5

V

rising 5.6 5.7 5.8

IN

VIN falling 6.5

rising 6.65 6.80 6.95

V

IN

rising 4.3 4.4 4.5 V

BAT

= 4.2V 1 µA

BAT

TA=+25°C 850 900 950

TA= 0°C to +85°C 800 1000

T

= -40°C to +0°C 780 1000

A

TA=+25°C 1850 1950 2050

T

= -40°C to +85°C 1750 1950 2150

A

130 190 µA

V

1%

V

mA

MAX4978–MAX4981

Overvoltage Protector with

Active Current Limit

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VIN= 5.0V, VEN= 0V, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 2)

Note 2: All devices are 100% production tested at TA= +25°C. Specifications over -40°C to +85°C are guaranteed by design.
Note 3: All timing is measured using 10% and 90% levels, unless otherwise noted.

Thermal-Shutdown Hysteresis 10 °C

EN Input High Voltage V
EN Input Low Voltage V
EN Input Leakage Current I
SDT Output Low Voltage V

SDT Leakage Current I

DYNAMIC (Note 3)

IN Debounce Time t

Switch Turn-On Time t

Switch Turn-Off Time t

Current-Limit Blanking Time t

Current-Limit Reaction Time t

Overcurrent Autoretry Time t

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

IH

IL

LKGE

OL

LKGS

DEB

ON

OFF

BLANK

REAC

RETRY

V EN = 5.5V or 0V -1 +1 µA

MAX4978/MAX4979, I

MAX4978/MAX4979, V
deasserted

V

< VIN < V

UVLO

enable, Figure 1

Time from V

, RL = 10Ω, CL = 10µF

of V

IN

VIN < V

UVLO

switch off, R

Short circuit applied, Figure 1 15 20 25 ms

Short circuit applied 5 µs

Figure 1 120 160 200 ms

OVLO

= 10% of VIN to V

OUT

or VIN > V

= 1kΩ

L

= 20mA 1 V

SINK

= 28V, SDT

SDT

to charge-pump

= 90%

OUT

to internal

OVLO

1.5 V

0.6 V

1µA

120 160 200 ms

1.5 ms

515µs