19-2664; Rev 1; 4/03
50mA/100mA Current-Limit Switches
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.
o
Thermal-Shutdown Protection
o
Reverse-Current Protection
o
0.7Ω On-Resistance
o
14ms Guaranteed Blanking Time
o
FLAG
Function (MAX4785/MAX4787)
o
65µA Supply Current
o
8µA Latch-Off Current (MAX4785/MAX4787)
o
0.01µA Shutdown Current
o
2.3V to 5.5V Supply Range
o
Undervoltage Lockout
o
Fast Current-Limit Response Time
o
Tiny SC70 Package
Features
o
Guaranteed Current Limit: 50mA, 100mA
MAX4785–MAX4788
Ordering Information
PART
MAX4785EXS-T
MAX4785EXK-T
MAX4786EXS-T
MAX4787EXS-T
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-
PACKAGE
4 SC70-4
5 SC70-5
4 SC70-4
4 SC70-4
5 SC70-5
4 SC70-4
TOP
MARK
AGE
ADL
AGF
AGG
AND
AGH
Applications
PDAs and Palmtop Devices
Cell Phones
GPS Systems
Hand-Held Devices
MAX4787EXK-T
MAX4788EXS-T
Selector Guide appears at end of data sheet.
Typical Operating Circuit
2.3V TO 5.5V
Pin Configurations
TOP VIEW
ON
OUT
1
GND
2
FLAG
3
5
IN
OUT
1
4
IN
IN
µP
MAX4785
MAX4787
4
ON
GND
2
MAX4785–
MAX4788
3
ON
MAX4785
MAX4787
FLAG
TO EXTERNAL PORT
OUT
GND
SC70
SC70
1
________________________________________________________________
Maxim Integrated Products
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.
50mA/100mA Current-Limit Switches
MAX4785–MAX4788
ABSOLUTE MAXIMUM RATINGS
IN, ON,
FLAG,
OUT to GND .....................................-0.3V to +6V
OUT Short Circuit to GND .................................Internally Limited
Continuous Power Dissipation (T
A
= +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 ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
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.
ELECTRICAL CHARACTERISTICS
(V
IN
= 2.3V to 5.5V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at V
IN
= 3.3V, T
A
= +25°C.) (Note 1)
PARAMETER
Operating Voltage
Quiescent Current
Latch-Off Current (Note 2)
Shutdown Current
Forward Current Limit
Reverse Current Limit
ON Input Leakage
Off Switch Leakage
Undervoltage Lockout
Undervoltage Lockout Hysteresis
On-Resistance
ON Input Logic High Voltage
ON Input Logic Low Voltage
FLAG
Output Logic Low Voltage
FLAG
Output High Leakage
Current
Thermal Shutdown
Thermal-Shutdown Hysteresis
DYNAMIC
Turn-On Time (Note 3)
Turn-Off Time (Note 3)
ON from low to high; I
OUT
= 10mA,
C
L
= 0.1µF
ON from high to low; I
OUT
= 10mA,
C
L
= 0.1µF
50
30
µs
ns
R
ON
V
IH
V
IL
I
SINK
= 1mA (MAX4785/MAX4787)
V
IN
= V
F LAG
= 5.5V (MAX4785/MAX4787)
150
15
T
A
= +25°C, I
OUT
= 20mA
T
A
= -40°C to +85°C, I
OUT
= 20mA
2.0
0.8
0.4
1
UVLO
SYMBOL
V
IN
I
Q
I
LATCH
I
SHDN
I
FWD
I
REV
V
ON
= V
IN
, I
OUT
= 0, V
IN
= 2.3V to 5.0V
switch on
V
IN
= 5.0V to 5.5V
V
ON
= V
IN
, after an overcurrent fault
(MAX4785/MAX4787)
V
ON
= 0V
MAX4785/MAX4786
MAX4787/MAX4788
MAX4785/MAX4786
MAX4787/MAX4788
V
ON
= V
IN
or GND
V
ON
= 0V, V
OUT
= 0V
Rising edge
1.8
100
0.7
1
1.3
-1
0.01
50
100
CONDITIONS
MIN
2.3
65
TYP
MAX
5.5
100
120
8
0.01
15
1
120
240
120
240
+1
1
2.2
UNITS
V
µA
µA
µA
mA
mA
µA
µA
V
mV
Ω
V
V
V
µA
°C
°C
2
_______________________________________________________________________________________
50mA/100mA Current-Limit Switches
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 2.3V to 5.5V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at V
IN
= 3.3V, T
A
= +25°C.) (Note 1)
PARAMETER
Blanking Time
Short-Circuit Current-Limit
Response Time
Retry Time (Note 4)
t
RETRY
SYMBOL
t
BLANK
CONDITIONS
Overcurrent fault, Figures 2, 3
V
ON
= V
IN
= 3.3V, short circuit applied to
OUT
MAX4786/MAX4788: overcurrent fault,
Figure 2
98
MIN
14
5
420
TYP
MAX
60
UNITS
ms
µs
ms
MAX4785–MAX4788
Note 1:
All parts are 100% tested at +25°C. Limits across the full temperature range are guaranteed by design and correlation.
Note 2:
Latch-off current does not include the current flowing into
FLAG.
Note 3:
The on-time is defined as the time taken for the current through the switch to go from 0mA to full load. The off-time is defined
as the time taken for the current through the switch to go from full load to 0mA.
Note 4:
Retry time is typically 7x the blanking time.
Typical Operating Characteristics
(V
IN
= 3.3V, T
A
= +25°C, unless otherwise noted.)
QUIESCENT SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX4785-01
SUPPLY CURRENT
vs. TEMPERATURE
MAX4785-02
LATCH-OFF CURRENT
vs. TEMPERATURE
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
-40
V
ON
= V
IN
MAX4785 toc03
90
80
SUPPLY CURRENT (µA)
70
60
50
40
30
20
10
0
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
V
ON
= V
IN
90
80
SUPPLY CURRENT (µA)
70
V
IN
= 3.3V
V
ON
= V
IN
V
IN
= 5V
50
40
30
20
10
0
LATCH-OFF (µA)
60
V
IN
= 5V
V
IN
= 3.3V
6.0
-40
-15
10
35
60
85
-15
10
35
60
85
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
TEMPERATURE (°C)
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
MAX4785-04
SHUTDOWN LEAKAGE CURRENT
vs. TEMPERATURE
MAX4785-05
LATCH-OFF LEAKAGE CURRENT
vs. TEMPERATURE
LATCH-OFF LEAKAGE CURRENT (nA)
MAX4785 toc06
10
SHUTDOWN SUPPLY CURRENT (nA)
10
SHUTDOWN LEAKAGE CURRENT (nA)
100
10
1
0.1
0.01
0.001
V
IN
= 5V
V
IN
= 3.3V
1
1
V
IN
= 5V
0.1
0.1
0.01
V
IN
= 3.3V
0.01
0.001
0.001
-40
-15
10
35
60
85
TEMPERATURE (°C)
0.0001
-40
0.0001
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
_______________________________________________________________________________________
3
50mA/100mA Current-Limit Switches
MAX4785–MAX4788
Typical Operating Characteristics (continued)
(V
IN
= 3.3V, T
A
= +25°C, unless otherwise noted.)
NORMALIZED ON-RESISTANCE
vs. TEMPERATURE
MAX4785-07
OUTPUT CURRENT
vs. OUTPUT VOLTAGE
MAX4785 toc08
1.4
1.2
NORMALIZED R
ON
1.0
0.8
0.6
0.4
0.2
0
-40
-15
10
35
60
V
CC
= 3.3V
300
250
OUTPUT CURRENT (mA)
200
150
100
50
0
MAX4785/MAX4786
MAX4787/MAX4788
85
0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 3.3
V
IN
- V
OUT
(V)
TEMPERATURE (°C)
SWITCH TURN-ON/OFF TIMES
vs. TEMPERATURE
MAX4785 toc09
FLAG-BLANKING TIMEOUT
vs. TEMPERATURE
MAX4785 toc10
100
ON
TURN-ON/OFF TIMES (µs)
10
I
LOAD
= 10mA
V
CC
= 3.3V
V
CC
= 5V
50
45
FLAG-BLANKING TIME (ms)
40
35
30
25
1
0.1
OFF
0.01
0.001
-40
-15
10
35
60
85
TEMPERATURE (°C)
20
-40
-15
10
35
60
85
TEMPERATURE (°C)
CURRENT-LIMIT RESPONSE
MAX4785 toc11
CURRENT-LIMIT RESPONSE
MAX4785 toc12
C
OUT
= 1µF
V
IN
= 3.3V
C
IN
= 1µF
V
IN
2V/div
V
ON
2V/div
V
IN =
V
ON
1V/div
I
OUT
100mA/div
V
IN =
V
ON
C
IN
= 1µF
C
OUT
= 1µF
20µs/div
I
OUT
100mA/div
40µs/div
4
_______________________________________________________________________________________
50mA/100mA Current-Limit Switches
Typical Operating Characteristics (continued)
(V
IN
= 3.3V, T
A
= +25°C, unless otherwise noted.)
CURRENT-LIMIT RESPONSE
(OUT SHORTED TO GND)
MAX4785 toc13
MAX4785–MAX4788
SWITCH TURN-ON TIME RESPONSE
MAX4785 toc14
C
IN
= 1µF
C
OUT
= 1µF
V
IN
= 3.3V
V
IN
2V/div
V
ON
V
OUT
2V/div
I
OUT
10mA/div
I
OUT
2A/div
40µs/div
100µs/div
SWITCH TURN-OFF TIME RESPONSE
MAX4785 toc15
FLAG-BLANKING RESPONSE
MAX4785 toc16
V
IN
= 3.3V
V
ON
2V/div
V
IN
2V/div
V
ON
2V/div
I
OUT
10mA/div
FLAG
2V/div
I
OUT
100mA/div
100ns/div
4ms/div
Pin Description
PIN
SC70
1
2
—
3
4
SC70
1
2
3
4
5
NAME
OUT
GND
FLAG
ON
IN
FUNCTION
Switch Output. Bypass with a 0.1µF capacitor to ground.
Ground
Fault Output. This open-drain output goes low when the device stays in forward or reverse
current limit for more than the blanking time period.
FLAG
is high impedance when a fault is
not present or when ON is low.
Active-High Switch-On Input. A logic high turns the switch on.
Input. Bypass with a 0.1µF ceramic capacitor to ground.
_______________________________________________________________________________________
5
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