Datasheet

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General Description

The MAX4785–MAX4788 family of switches feature inter-

nal current limiting to prevent host devices from being

damaged due to faulty load conditions. These analog

switches have a low 0.7Ω on-resistance and operate

from a 2.3V to 5.5V input voltage range. They are avail-

able with guaranteed 50mA and 100mA current limits,

making them ideal for load-switching applications.

When the switch is on and a load is connected to the

port, a guaranteed blanking time of 14ms ensures that

the transient voltages settle down. If after this blanking

time the load current is greater than the current limit,

the MAX4785 and MAX4787 enter a latch-off state

where the switch is turned off and FLAG is issued to the

microprocessor. The switch can be turned on again by

cycling the power or the ON pin.

The MAX4786 and MAX4788 have an autoretry feature

where the switch turns off after the blanking time and

then continuously checks to see if the overload condi-

tion is present. The switch remains on after the overload

condition disappears.

The MAX4785 and MAX4787 are available in a tiny

space-saving 4-pin or 5-pin SC70 package. The

MAX4786 and MAX4788 are available only in the 4-pin

SC70 package. For higher current current-limiting

switches, refer to the MAX4789–MAX4794 and

MAX1693 data sheets.

Applications

PDAs and Palmtop Devices

Cell Phones

GPS Systems

Hand-Held Devices

Features

♦ Guaranteed Current Limit: 50mA, 100mA

♦ Thermal-Shutdown Protection

♦ Reverse-Current Protection

♦ 0.7Ω On-Resistance

♦ 14ms Guaranteed Blanking Time

♦ FLAG Function (MAX4785/MAX4787)

♦ 65µA Supply Current

♦ 8µA Latch-Off Current (MAX4785/MAX4787)

♦ 0.01µA Shutdown Current

♦ 2.3V to 5.5V Supply Range

♦ Undervoltage Lockout

♦ Fast Current-Limit Response Time

♦ Tiny SC70 Package

MAX4785–MAX4788

50mA/100mA Current-Limit Switches

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

2.3V TO 5.5V

OUT

FLAG

GND

µP

TO EXTERNAL PORT

MAX4785

MAX4787

Typical Operating Circuit

19-2664; Rev 1; 4/03

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.

Selector Guide appears at end of data sheet.

PART

TEMP RANGE

PIN-

PACKAGE

TOP

MARK

MAX4785EXS-T

-40°C to +85°C

4 SC70-4

AGE

MAX4785EXK-T

-40°C to +85°C

5 SC70-5 ADL

MAX4786EXS-T

-40°C to +85°C

4 SC70-4 AGF

MAX4787EXS-T

-40°C to +85°C

4 SC70-4

AGG

MAX4787EXK-T

-40°C to +85°C

5 SC70-5

AND

MAX4788EXS-T

-40°C to +85°C

4 SC70-4

AGH

GND

15INOUT

MAX4785

MAX4787

SC70

TOP VIEW

FLAG ON

14INOUT

MAX4785–

MAX4788

SC70

23GND

Pin Configurations

Summary of content (10 pages)

PAGE 1
9-2664; Rev 1; 4/03 50mA/100mA Current-Limit Switches Features The MAX4785–MAX4788 family of switches feature internal current limiting to prevent host devices from being damaged due to faulty load conditions. These analog switches have a low 0.7Ω on-resistance and operate from a 2.3V to 5.5V input voltage range. They are available with guaranteed 50mA and 100mA current limits, making them ideal for load-switching applications.
PAGE 2
MAX4785–MAX4788 50mA/100mA Current-Limit Switches ABSOLUTE MAXIMUM RATINGS IN, ON, FLAG, OUT to GND .....................................-0.3V to +6V OUT Short Circuit to GND .................................Internally Limited Continuous Power Dissipation (TA = +70°C) 4-Pin SC70 (derate 3.1mW/°C above +70°C) ..............245mW 5-Pin SC70 (derate 3.1mW/°C above +70°C) ..............247mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ............................
PAGE 3
50mA/100mA Current-Limit Switches (VIN = 2.3V to 5.5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VIN = 3.3V, TA = +25°C.) (Note 1) PARAMETER SYMBOL Blanking Time CONDITIONS tBLANK MIN Overcurrent fault, Figures 2, 3 Short-Circuit Current-Limit Response Time TYP 14 VON = VIN = 3.3V, short circuit applied to OUT Retry Time (Note 4) UNITS 60 ms 5 MAX4786/MAX4788: overcurrent fault, Figure 2 tRETRY MAX µs 98 420 ms Note 1: All parts are 100% tested at +25°C.
PAGE 4
Typical Operating Characteristics (continued) (VIN = 3.3V, TA = +25°C, unless otherwise noted.) NORMALIZED ON-RESISTANCE vs. TEMPERATURE OUTPUT CURRENT vs. OUTPUT VOLTAGE 250 OUTPUT CURRENT (mA) 0.8 0.6 0.4 150 100 MAX4785/MAX4786 50 0.2 0 0 -40 -15 10 35 60 85 VIN - VOUT (V) SWITCH TURN-ON/OFF TIMES vs. TEMPERATURE FLAG-BLANKING TIMEOUT vs. TEMPERATURE VCC = 3.3V 45 FLAG-BLANKING TIME (ms) ILOAD = 10mA VCC = 5V 0.1 OFF 0.01 50 MAX4785 toc09 ON 1 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.
PAGE 5
0mA/100mA Current-Limit Switches CURRENT-LIMIT RESPONSE (OUT SHORTED TO GND) SWITCH TURN-ON TIME RESPONSE MAX4785 toc13 CIN = 1µF COUT = 1µF MAX4785 toc14 VIN = 3.3V VIN 2V/div VON VOUT 2V/div IOUT 10mA/div IOUT 2A/div 40µs/div 100µs/div FLAG-BLANKING RESPONSE SWITCH TURN-OFF TIME RESPONSE MAX4785 toc16 MAX4785 toc15 VIN = 3.
PAGE 6
MAX4785–MAX4788 50mA/100mA Current-Limit Switches REVERSE-CURRENT DETECTOR MAX4785/MAX4787 ONLY FLAG BLANKING TIME CIRCUITRY N FORWARD CURRENT DETECTOR N IN ON UNDERVOLTAGE LOCKOUT OUT +2.0V LOGIC GND AUTORETRY MAX4785–MAX4788 Figure 1. MAX4785–MAX4788 Functional Diagram Detailed Description The MAX4785–MAX4788 are forward/reverse currentlimited switches that operate from a 2.3V to 5.5V input voltage range and guarantee a 50mA and 100mA minimum current-limit threshold for different options.
PAGE 7
50mA/100mA Current-Limit Switches ON FAULT SWITCH ON/OFF SUPPLY CURRENT MODE Low X OFF Shutdown High Undervoltage lockout OFF Shutdown High Thermal High Current limit OFF immediately (tBLANK period does not apply) Latch off OFF after tBLANK period has elapsed Latch off ON during tBLANK period, OFF during tRETRY period for the MAX4786 and MAX4788; cycle repeats until fault is removed See the Autoretry section FLAG Indicator The MAX4785 and MAX4787 feature a latched fault output, FLAG.
PAGE 8
MAX4785–MAX4788 50mA/100mA Current-Limit Switches tBLANK the MAX4785–MAX4788 from tripping erroneously. If the load capacitance is too large, then current may not have enough time to charge the capacitance and the device assumes that there is a faulty load condition.
PAGE 9
50mA/100mA Current-Limit Switches SC70, 4L.EPS PACKAGE OUTLINE, 4L SC70 21-0098 C 1 1 Chip Information TRANSISTOR COUNT: 1659 PROCESS: BiCMOS _______________________________________________________________________________________ 9 MAX4785–MAX4788 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.
PAGE 10
Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) SC70, 5L.EPS MAX4785–MAX4788 50mA/100mA Current-Limit Switches PACKAGE OUTLINE, 5L SC70 21-0076 C 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.