MAXIM MAX4995A, MAX4995AF, MAX4995AL, MAX4995B, MAX4995C User Manual

General Description

The MAX4995A/MAX4995AF/MAX4995AL/MAX4995B/
MAX4995C programmable current-limit switches fea­ture internal current limiting to prevent damage to host
devices due to faulty load conditions. These analog
switches feature a low 130mΩ (typ) on-resistance and
operate from a +1.7V to +5.5V input voltage range. The
current limit is adjustable from 50mA to 600mA, making
these devices ideal for SDIO (secure digital input/out­put) and other load-switching applications.

Each device in the family handles an overcurrent event
differently depending on the option selected. The
MAX4995A/MAX4995AF/MAX4995AL go into an
autoretry mode, the MAX4995B latches off the switch,
and the MAX4995C places the device in a continuous
current-limit mode. Additional safety features include
thermal shutdown to prevent overheating and reverse­current blocking to prevent current from being driven
back into the source.

The MAX4995A/MAX4995AF/MAX4995AL/MAX4995B/
MAX4995C are available in a tiny 10-pin, 1.4mm x

1.8mm UTQFN, a 6-pin SOT23, or an 8-pin, 2mm x
2mm TDFN package and operate over the -40°C to
+125°C extended temperature range.

Features

♦ 50mA to 600mA Programmable Current Limit

♦ ±10% Accurate Current Limit
♦ Overload FLAG Threshold

♦ Low Dropout Voltage

♦ Short-Circuit Protection

♦ Thermal Shutdown

♦ Reverse-Current Protection

♦ 170µA (typ) Supply Current

♦ +1.7V to +5.5V Supply Voltage Range

♦ Tiny 10-Pin, 1.4mm x 1.8mm UTQFN Package

Applications

MAX4995A/AF/AL/MAX4995B/MAX4995C

50mA to 600mA Programmable

Current-Limit Switches

________________________________________________________________

Maxim Integrated Products

1

Ordering Information/Selector Guide

19-4363; Rev 2; 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.

All devices operate over the -40°C to +125°C temperature range.

+

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

T = Tape and reel.

*

Future product. Contact factory for availability.

**

EP = Exposed pad.

Typical Operating Circuit appears at end of data sheet.

SDIO Ports

USB Ports

Notebook VGA Ports

GPS

Cell Phones

MP3 Players

UTCA/ATCA Platforms

PART PIN-PACKAGE ON POLARITY

MAX4995AAUT+T* 6 SOT23 Active-High Autoretr y Normal +ACNZ

MAX4995AAVB+T 10 UTQFN Active-High Autoretry Normal +AAM

MAX4995AATA+T 8 TDFN-EP** Active-High Autoretr y Normal +ABL

MAX4995AFAUT+T* 6 SOT23 Active-High Autoretry Fast +ACOE

MAX4995AFAVB+T 10 UTQFN Active-High Autoretr y Fast +AAR

MAX4995AFATA+T* 8 TDFN-EP** Acti ve-High Autoretry Fast + ACO

MAX4995ALAUT+T* 6 SOT23 Active-Low Autoretry Normal +ACDA

MAX4995ALAVB+T 10 UTQFN Active-Low Autoretry Normal +AAN

MAX4995ALATA+T* 8 TDFN-EP** Active-Low Autoretry Normal +ABM

MAX4995BAUT+T* 6 SOT23 Active-High Latchoff Normal +ACDB

MAX4995BAVB+T 10 UTQFN Active-High Latchoff Normal +AAO

MAX4995BATA+T* 8 TDFN-EP** Active-High Latchoff Normal +ABN

MAX4995CAUT+T* 6 SOT23 Active-High Cont inuous Normal +ACOD

MAX4995CAVB+T 10 UTQFN Active-High Continuou s Normal + AAQ

MAX4995CATA+T* 8 TDFN-EP** Active-High Continuous Normal + ABP

OVERCURRENT

RESPONSE

SHORT-CIRCUIT

RESPONSE

TOP MARK

MAX4995A/AF/AL/MAX4995B/MAX4995C

50mA to 600mA Programmable
Current-Limit Switches

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

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.

IN, ON, ON, FLAG, OUT, and SETI to GND .............-0.3V to +6V

Current into Any Pin (Except IN, OUT)................................20mA

OUT Short Circuit to GND .................................................800mA

Continuous Power Dissipation (T

A

= +70°C) (Note 1)

10-Pin UTQFN (derate 6.99mW/ °C above T

A

= +70°C) ..559mW

6-Pin SOT23 (derate 13.4mW/ °C above T

A

= +70°C)...1072.4mW

8-Pin TDFN (derate 11.9mW/ °C above T

A

= +70°C)....953.5mW

Junction-to-Ambient Thermal Resistance (θ

JA

)

(Note 2).....................................................................143.1°C/W

Operating Temperature Range .........................-40°C to +125°C

Storage Temperature Range .............................-65°C to +150°C

Junction Temperature......................................................+150°C

Lead Temperature (soldering, 10s) .................................+300°C

Note 1: These power limits are defined by the thermal characteristics of the package, maximum function temperature (+150°C), and

the JEDEC51-7 defined setup. Maximum power dissipation could be lower, limited by the thermal-shutdown protection
included in this IC.

Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-

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

.

ELECTRICAL CHARACTERISTICS

(VIN= +1.7V to +5.5V, R

SETI

= 94.3kΩ, CIN= 1µF, and TA= TJ= -40°C to +125°C, unless otherwise noted. Typical values are at VIN= +3.3V,

T

A

= +25°C.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

SUPPLY OPERATION

Operating Voltage VIN 1.7 5.5 V

Quiescent Current IQ I

Latchoff Current I

Shutdown Forward Current I

Shutdown Reverse Current I

INTERNAL FET

Switch-On Resistance R

Normalized Current-Limit Accuracy

(R

+ 2.48) x I

SETI

LIM

Reverse Blocking Current

Reverse Blocking Threshold

FLAG Assertion Drop Voltage
Threshold

ON, ON INPUT

ON, ON Input Leakage I
ON, ON Input Logic-High Voltage V
ON, ON Input Logic-Low Voltage V

= 0, switch on, VIN= 3.3V 170 300 μA

OUT

LATCH

SHDN VON

RSHDN

Product

VIN = 3.3V, I
fault (MAX4995B)

V
V

VIN = 3.3V, I

ON

I

LIM

V

I

LIM

V

V

= 0, VON = VIN, VIN= 5.5V, V

= 0, VON = VIN, VIN= 1.7V,

ON

= 5.5V (current into OUT)

OUT

= 50mA to 600mA, VIN - V

= 3.3V (Note 3)

IN

= 50mA to 600mA, VIN - V

= 3.3V

IN

OUT

limit shutdown

V

OUT

turns on

V

LEAK

Increase (VIN - V

FA

asserts, I

VON, VON = VINor GND -1 +1 μA

1.6 V

IH

0.4 V

IL

> VIN+ 300mV after reverse-current-

= VIN+ 300mV, OUT falling until switch

= 0 after an overcurrent

OUT

lower than I

OUT

) drop until FLAG

OUT

limiting, VIN = 3.3V

OUT

LIM

8 15 μA

= 0 0.01 5 μA

OUT

0.01 1 μA

= 1V,

OUT

OUT

= 1V,

0.9 1 1.1 —

26138 29042 31946 V

10 μA

35 110 210 mV

130 350 m

650 mV

MAX4995A/AF/AL/MAX4995B/MAX4995C

50mA to 600mA Programmable

Current-Limit Switches

_______________________________________________________________________________________ 3

Note 3: I

LIM

is forward current limit.

Note 4: Turn-on time and turn-off time are defined as the difference in the time between when the output crosses 10% and 90%

of the final output voltage.

Note 5: Blanking time and retry time are generated by the same oscillator. Therefore, the ratio of

is a constant value of 32. See Figures 2 and 3.

ELECTRICAL CHARACTERISTICS (continued)

(VIN= +1.7V to +5.5V, R

SETI

= 94.3kΩ, CIN= 1µF, and TA= TJ= -40°C to +125°C, unless otherwise noted. Typical values are at VIN= +3.3V,

T

A

= +25°C.)

Figure 1. Timing Diagram for Measuring Turn-On Time (tSS) and Turn-Off Time (t

OFF

).

FLAG OUTPUT

FLAG Output Logic-Low Voltage I
FLAG Output Leakage Current VIN= V

DYNAMIC

Turn-On Time t

Turn-Off Time t

Current-Limit Reaction Time t

Blanking Time t

Retry Time t

THERMAL PROTECTION

Thermal Shutdown +150 °C

Thermal-Shutdown Hysteresis 15 °C

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

I (mA)

LIM

=

= 1mA 0.4 V

SINK

= 5.5V, FLAG deasserted 1 μA

FLAG

2

9042( )

V

R(k 2.48k

SETI

+

)()

ΩΩ

SS

OFF

LIM

BLANK

RETRY

VIN= 3.3V, C
(Note 4)

Switch from on to off, VIN= 3.3V, C
R

= 20 , Figure 1 (Note 4)

L

VIN= 3.3V, R
578k , output high and
then short-circuit
applied

(Note 5) 10 16.3 22.6 ms

MAX4995A/MAX4995AF/MAX4995AL (Note 5) 320 723.2 ms

= 1μF, RL = 20 , Figure 1,

OUT

=

SETI

MAX4995A/AL/B/C 5

MAX4995AF 1.5

OUT

= 1μF,

120 μs

120 μs

μs

t

RETRY

t

BLANK

t

SS

90%

V

OUT

10%

90%

t

10%

OFF

MAX4995A/AF/AL/MAX4995B/MAX4995C

50mA to 600mA Programmable
Current-Limit Switches

4 _______________________________________________________________________________________

μ

μ

Typical Operating Characteristics

(VIN= +3.3V, CIN= 1µF, C

OUT

= 1µF, R

SETI

= 94.2kΩ, TA= +25°C, unless otherwise noted.)

CURRENT LIMIT

vs. SUPPLY VOLTAGE

315

MAX4995AL

310

305

300

295

CURRENT LIMIT (mA)

290

285

2.0 3.02.5 4.5 5.03.5 4.0

1.5 5.5
SUPPLY VOLTAGE (V)

CURRENT-LIMIT RESPONSE (MAX4995A)

SUDDEN SHORT

APPLIED AT OUTPUT

MAX4995A toc03

MAX4995A toc01

V

OUT

(2V/div)

I

OUT

(10A/div)

NORMALIZED CURRENT LIMIT

vs. TEMPERATURE

1.100
MAX4995AL

1.075

1.050

1.025

1.000

0.975

0.950

NORMALIZED CURRENT LIMIT

0.925

0.900

-25 5-10 20

-40 50 8065 95 11035 125
TEMPERATURE (°C)

CURRENT-LIMIT RESPONSE (MAX4995AF)

SUDDEN SHORT

APPLIED AT OUTPUT

MAX4995A toc04

MAX4995A toc02

V

OUT

(2V/div)

I

OUT

(10A/div)

10

s/div

s/div

10

QUIESCENT SUPPLY CURRENT

CURRENT-LIMIT RESPONSE

4ms/div

MAX4995A toc05

R

LOAD

= 8Ω

V

OUT

(2V/div)

I

OUT

(100mA/div)

300

280

260

240

220

200

180

160

140

QUIESCENT SUPPLY CURRENT (μA)

120

100

1.5 5.5

vs. SUPPLY VOLTAGE

MAX4995A

2.0 3.02.5 4.5 5.03.5 4.0
SUPPLY VOLTAGE (V)

MAX4995A toc06

MAX4995A/AF/AL/MAX4995B/MAX4995C

50mA to 600mA Programmable

Current-Limit Switches

_______________________________________________________________________________________ 5

Typical Operating Characteristics (continued)

(VIN= +3.3V, CIN= 1µF, C

OUT

= 1µF, R

SETI

= 94.2kΩ, TA= +25°C, unless otherwise noted.)

QUIESCENT SUPPLY LIMIT

vs. TEMPERATURE

MAX4995A toc07

QUIESCENT SUPPLY CURRENT (μA)

180

190

200

240

170

230

160

220

150

210

250

260

140

VIN = 5V

MAX4995AL

VIN = 3.3V

TEMPERATURE (°C)

-25 5-10 20-40 50 8065 95 11035 125

SHUTDOWN SUPPLY CURRENT

vs. TEMPERATURE

MAX4995A toc08

SHUTDOWN SUPPLY CURRENT (μA)

1.00

0.50

1.50

0.75

1.75

2.00

2.25

0.25

1.25

2.50

0

VIN = 5V

VIN = 3.3V

MAX4995AL

TEMPERATURE (°C)

-25 5-10 20-40 50 8065 95 11035 125

SHUTDOWN FORWARD CURRENT

80

70

60

50

40

30

20

SHUTDOWN FORWARD CURRENT (nA)

10

0

vs. TEMPERATURE

MAX4995C

VIN = 5V

VIN = 1.7V

-25 5-10 20-40 50 8065 95 11035 125
TEMPERATURE (°C)

MAX4995A toc09

225

200

175

150

125

100

75

50

SHUTDOWN REVERSE CURRENT (nA)

25

0

1.5

1.4

1.3

1.2

1.1

1.0

0.9

0.8

NORMALIZED ON-RESISTANCE

0.7

0.6

0.5

SHUTDOWN REVERSE CURRENT

vs. TEMPERATURE

MAX4995C

= 5.5V

V

OUT

VIN = 5V

VIN = 1.7V

-25 5-10 20-40 50 8065 95 11035 125
TEMPERATURE (°C)

NORMALIZED ON-RESISTANCE

vs. TEMPERATURE

MAX4995C

= 3.3V

V

IN

-25 5-10 20-40 50 8065 95 11035 125
TEMPERATURE (°C)

MAX4995A toc10

MAX4995A toc13

LATCHOFF CURRENT

vs. TEMPERATURE

20

MAX4995B

18

16

14

12

10

LATCHOFF CURRENT (μA)

8

6

-25 5-10 20-40 50 8065 95 11035 125

VIN = 5V

TEMPERATURE (°C)

SWITCH TURN-ON TIME

vs. TEMPERATURE

180

MAX4995C

170

160

150

140

130

120

SWITCH TURN-ON TIME (μs)

110

100

= 10mA

I

LOAD

VIN = 5V

VIN = 3.3V

-25 5-10 20-40 50 8065 95 11035 125
TEMPERATURE (°C)

VIN = 3.3V

1.040
MAX4995C

1.035
I

OUT

1.030

MAX4995A toc11

1.025

1.020

1.015

1.010

1.005

1.000

0.995

NORMALIZED ON-RESISTANCE

0.990

0.985

0.980

1.7 5.2

1.6
MAX4995C

1.5
I

MAX4995A toc14

LOAD

1.4

1.3

1.2

1.1

1.0

0.9

SWITCH TURN-OFF TIME (ms)

0.8

0.7

0.6

-25 5-10 20-40 50 8065 95 11035 125

NORMALIZED ON-RESISTANCE

vs. SUPPLY VOLTAGE

< I

LIM

2.2 4.72.7 3.7 4.23.2
SUPPLY VOLTAGE (V)

SWITCH TURN-OFF TIME

vs. TEMPERATURE

= 10mA

VIN = 5V

VIN = 3.3V

TEMPERATURE (°C)

MAX4995A toc12

MAX4995A toc15

MAX4995A/AF/AL/MAX4995B/MAX4995C

50mA to 600mA Programmable
Current-Limit Switches

6 _______________________________________________________________________________________

μ

Typical Operating Characteristics (continued)

(VIN= +3.3V, CIN= 1µF, C

OUT

= 1µF, R

SETI

= 94.2kΩ, TA= +25°C, unless otherwise noted.)

SWITCH TURN-ON TIME RESPONSE

200μs/div

FLAG RESPONSE (OVERLOAD) CONDITION

100ms/div

MAX4995A toc16

MAX4995A toc18

V

ON

(5V/div)

V

OUT

(2V/div)

I

OUT

(200mA/div)

V

OUT

(2V/div)

V

FLAG

(2V/div)

SWITCH TURN-OFF TIME RESPONSE

200

SWITCH DROPOUT VOLTAGE

vs. TEMPERATURE

19

MAX4995A

18

= 100mA

I

LOAD

17

16

15

14

13

12

11

SWITCH DROPOUT VOLTAGE (mV)

10

9

-25 5-10 20-40 50 8065 95 11035 125
TEMPERATURE (°C)

s/div

MAX4995A toc17

VIN = 3.3V

V

ON

(5V/div)

V

OUT

(2V/div)

MAX4995A toc19

I

(mA)

OUT

I

350

300

250

200

150

100

50

0

OUT

MAX4995B

VIN = 5.5V

70 490 5604200

210 630140 280 350 700

/FLAG vs. V

V

DROP

DROP

(mV)

(VIN - V

OUT

)

1

MAX4995A toc20

FLAG (LOGIC-LEVEL STATUS)

0

MAX4995A/AF/AL/MAX4995B/MAX4995C

50mA to 600mA Programmable

Current-Limit Switches

_______________________________________________________________________________________ 7

Pin Description

Pin Configurations

TOP VIEWS

IN

N.C.

OUT

10 8

9

MAX4995A/MAX4995AF
MAX4995AL/MAX4995B

MAX4995C

35

4

ON (ON)* GND

SETI

UTQFN

6 FLAG1OUT

7 OUT1IN

6 N.C.2FLAG

MAX4995A/MAX4995AF
MAX4995AL/MAX4995B

MAX4995C

5IN2GND

4 ON (ON)*3SETI

SOT23

(1.6mm × 2.9mm)

OUT GND

865

MAX4995A/MAX4995AF
MAX4995AL/MAX4995B

+

1

IN FLAGIN

(1.4mm ×× 1.8mm)

*( ) FOR THE MAX4995AL ONLY.
**EXPOSED PAD. CONNECT EP TO GND.

(2mm × 2mm)

PIN (UTQFN) PIN (TDFN-EP) PIN (SOT23)

MAX4995AL MAX4995_ MAX4995AL MAX4995_ MAX4995AL MAX4995_

1, 10 1, 10 1, 2 1, 2 5 5 IN

2 2 3 3 6 6 FLAG

3 — 4 — 4 — ON

— 3 — 4 — 4 ON

4 4 5 5 2 2 GND Ground

5 5 6 6 3 3 SETI

NAME FUNCTION

Power Input. Bypass IN with a
1μF ceramic capacitor to ground.
Use higher capacitance to
prevent large load transients from
pulling down the supp ly voltage if
necessary. Connect both power
inputs (IN) together.

Open-Drain, Overload Indicator
Output. FLAG goes low when the
overload fault duration exceeds
the blanking time, reverse current
is detected, thermal shutdown
mode is active, or SETI is
connected to ground.

Active-Low, Switch-On Input.
Drive ON low to turn on the switch.

Active-High, Switch-On Input.
Drive ON high to turn on the switch.

Overload Current Limit Adjust.
Connect a resistor from SETI to
ground to program the
overcurrent limit. Do not connect
any capacitance larger than 20pF
to SETI.

N.C.

SETI

7

MAX4995C

2

TDFN

*EP

34

ON (ON)*

MAX4995A/AF/AL/MAX4995B/MAX4995C

50mA to 600mA Programmable
Current-Limit Switches

8 _______________________________________________________________________________________

Functional Diagram

Pin Description (continued)

PIN (UTQFN) PIN (TDFN-EP) PIN (SOT23)

MAX4995AL MAX4995_ MAX4995AL MAX4995_ MAX4995AL MAX4995_

6, 9 6, 9 7 7 — — N.C.

7, 8 7, 8 8 8 1 1 OUT

— — — — — — EP

MAX4995A/MAX4995AF/
MAX4995AL/MAX4995B/

MAX4995C

REVERSE­CURRENT

PROTECTION

NAME FUNCTION

No Connect. Not internally
connected.

Switch Output. Bypass OUT with
a 1μF capacitor to ground.
Connect both outputs (OUT)
together.

Exposed Pad. Connect EP to
GND. For TDFN package only.

IN

THERMAL

SHUTDOWN

UVLO

N.C.

ON (ON)*

SOFT-START

*( ) FOR THE MAX4995AL ONLY.

BUFFER

BANDGAP

REFERENCE

CURRENT

LIMIT

CONTROL

LOGIC

TIMING

CIRCUITRY

BUFFER

GND

OUT

FLAG

SETI

MAX4995A/AF/AL/MAX4995B/MAX4995C

50mA to 600mA Programmable

Current-Limit Switches

_______________________________________________________________________________________ 9

Detailed Description

The MAX4995A/MAX4995AF/MAX4995AL/MAX4995B/
MAX4995C programmable current-limit switches oper­ate from +1.7V to +5.5V and provide internal current
limiting adjustable from 50mA to 600mA. These devices
feature a fixed blanking time and a FLAG output that
notifies the processor when a fault condition is present.

Programmable Current Limit

A resistor from SETI to GND programs the current limit
for the switch (see the

Setting the Current Limit

sec­tion). If the output current exceeds the current limit for a
time equal to or longer than t

BLANK

, the output flag
asserts and the MAX4995A/MAX4995AF/MAX4995AL
enter the autoretry mode. The MAX4995B latches off
the switch, and the MAX4995C enters the continuous
current-limit mode.

Autoretry (MAX4995A/MAX4995AF/

MAX4995AL)

When the forward current reaches the current-limit
threshold, the t

BLANK

timer begins counting (Figure 2).

FLAG asserts if the overcurrent-limit condition is pre­sent for t

BLANK

. The timer resets if the overcurrent con-

dition disappears before the blanking time (t

BLANK

) has

elapsed. A retry time delay (t

RETRY

) starts immediately
after the blanking time has elapsed and during that
time, the switch latches off. At the end of t

RETRY

, the
switch turns on again. If the fault still exists, the cycle
repeats. If the fault has been removed, the switch stays
on. During this cycle, FLAG stays low. In autoretry if
the thermal power rating of the package is exceeded,
the MAX4995A/MAX4995AF/MAX4995AL go into ther­mal shutdown.

The autoretry feature saves system power in case of an
overcurrent or short-circuit condition. During t

BLANK

time when the switch is on, the supply current is held at
the current limit. During time t

RETRY

when the switch is
off, the current through the switch is zero. Thus, the
average output current is much less than the pro­grammed current limit. Calculate the average output
current using the following equation:

I

LOAD

= I

LIM [tBLANK

/(t

BLANK

+ t

RETRY

)]

With a typical t

BLANK

= 16.3ms and typical t

RETRY

=
524ms, the duty cycle is 3%, resulting in a 97% power
savings over the switch being on the entire time.

Latchoff (MAX4995B)

When the forward current reaches the current-limit
threshold, the t

BLANK

timer begins counting (Figure 3).

FLAG asserts if an overcurrent-limit condition is present
for greater than t

BLANK

time. The timer resets if the over-

current condition disappears before t

BLANK

has
elapsed. The switch turns off if the overcurrent condition
continues beyond the blanking time. Reset the switch
by either toggling the control logic (ON) or cycling the
input voltage. If the thermal power rating of the pack­age is exceeded during t

BLANK

, the MAX4995B goes

into thermal shutdown.

Continuous Current Limit (MAX4995C)

When the forward current reaches the forward current­limit threshold, the MAX4995C limits the output current
to the programmed current limit. FLAG asserts if the
current limit is present for t

BLANK

and deasserts when
the overload condition is removed. In this mode, if the
thermal power rating of the package is exceeded, the
MAX4995C goes into thermal shutdown.

Switch-On/Off Control

The ON input for the MAX4995_/MAX4995AF and ON
input for the MAX4995AL control the switch; see Table

1. Toggle ON for the MAX4995B to reset the fault condi­tion once the short current is detected and the device
shuts down.

Reverse-Current Protection

The MAX4995 features a reverse-current protection cir­cuit that limits the backflow current to 10µA when the
output voltage exceeds the input voltage by 110mV
(typ). The switch turns off and FLAG asserts without
waiting for t

BLANK

to elapse. The switch turns back on

and FLAG deasserts when the output voltage drops
below the detecting threshold by 10mV (typ).

Table 1. Switch Truth Table

MAX4995_/

MAX4995AF

ON ON

0 1 Off

10On

MAX4995AL

SWITCH
STATUS

MAX4995A/AF/AL/MAX4995B/MAX4995C

50mA to 600mA Programmable
Current-Limit Switches

10 ______________________________________________________________________________________

FLAG

Indicator

FLAG is an open-drain fault indicator output and requires
an external pullup resistor to a DC supply. FLAG goes
low when any of the following conditions occurs:

• The device is in current-limit mode.

• The OUT voltage is above the IN voltage by more
than 110mV (typ).

• The die temperature exceeds the thermal-shutdown
temperature limit of +150°C.

• SETI is connected to ground.

Thermal Shutdown

Thermal-shutdown circuitry protects the devices from
overheating. The switch turns off and FLAG goes low
immediately when the junction temperature exceeds
+150°C (typ). The switch turns on again after the device
temperature drops by approximately 15°C (typ).

Figure 2. Autoretry Fault Diagram

Figure 3. Latchoff Fault Diagram

OUT

CURRENT LIMIT

LOAD CURRENT

FLAG

t

BLANK

OUT

t

RETRY

t

t

BLANK

BLANK

t

RETRY

t

BLANK

t

BLANK

t

BLANK

THE DEVICE GOES TO
THERMAL-SHUTDOWN MODE

CURRENT LIMIT

LOAD CURRENT

THE DEVICE GOES TO

THERMAL-SHUTDOWN MODE

FLAG

MAX4995A/AF/AL/MAX4995B/MAX4995C

50mA to 600mA Programmable

Current-Limit Switches

______________________________________________________________________________________ 11

Applications Information

Setting the Current Limit

A resistor from SETI to ground programs the current-limit
value for the MAX4995. Table 2 lists various current lim­its set by different resistor values at SETI. Shorting SETI
to ground asserts FLAG.

Use the following formula to calculate the current limit:

Using an R

SETI

with a value smaller than 45.8kΩ results
in a higher current limit. A programmed output current
greater than 660mA can damage the device.

Connecting any capacitance larger than 20pF to SETI
can cause instability.

Input Capacitor

Connect a capacitor from IN to GND to limit the input
voltage drop during momentary output short-circuit
conditions. Use a 1µF minimum ceramic capacitor for
proper device operation. Larger capacitor values
reduce the voltage undershoot at the input.

Due to the very fast current-limit reaction time of the
MAX4995AF, a larger input capacitance might need to
be connected at the input to dampen oscillation due to
long wires. Choose a value large enough to ensure IN
doesn’t exceed the absolute maximum ratings.

Output Capacitor

For stable operation over the full temperature range
and over the full programmable current-limit range, use
a 1µF ceramic capacitor from OUT to ground.

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.
Calculate the maximum capacitive load (C

MAX

) value that

can be connected to OUT using the following formula:

For example, for V

IN

= 3.3V, t

BLANK(MIN)

= 10ms, and

I

LIM

= 300mA, C

MAX

equals 909µF.

Due to the very fast current-limit reaction time of the
MAX4995AF, a larger output capacitance might need to
be connected at the output to dampen oscillation due
to long wires. Choose a value large enough to ensure
OUT doesn’t exceed the absolute maximum ratings.

Layout and Thermal Dissipation

To optimize the switch response time to output short­circuit conditions, it is very important to keep all traces
as short as possible to reduce the effect of undesirable
parasitic inductance. Place input and output capacitors
as close as possible to the device. IN and OUT must be
connected with wide, short traces to the power bus.
During normal operation, the power dissipation is small
and the package temperature change is minimal. If the
output is continuously shorted to ground at the maxi­mum supply voltage, the operation of the switches with
the autoretry option does not cause problems because
the total power dissipated during the short is scaled by
the duty cycle:

Attention must be given to the MAX4995C continuous
current-limit version when the power dissipation during
a fault condition may cause the device to reach thermal
shutdown threshold.

Table 2. Current Limit vs. Resistor Values

2

9042( )

V

R(k)

ΩΩ=

SETI

I(A

LIM

R

(kΩ) TYPICAL CURRENT LIMIT (mA)

SETI

45.8 602

55.6 500

70.6 397

94.2 300

143 200

191 150

287 100

576 50

∞ (Open) 0

−

2.48 k

)

m

()

I (mA) t (ms )

C(F)

MAX

LIM BLANK(MIN)

μ=

×

V(

V)

IN

P

MAX

VI t

IN(MA X) OUT(MAX) BLANK

=

××

tt

RETRY BLANK

+

MAX4995A/AF/AL/MAX4995B/MAX4995C

50mA to 600mA Programmable
Current-Limit Switches

12 ______________________________________________________________________________________

Typical Operating Circuit

Chip Information

PROCESS: BiCMOS

PACKAGE TYPE PACKAGE CODE DOCUMENT NO.

10 UTQFN V101A1CN+1

21-0028

6 SOT23 U6SN+1

21-0058

8 TDFN T822+1

21-0168

Package Information

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.

V

CC

V

IO

FLAG

µP

R

SETI

ON
(ON*)

SETI

*( ) FOR THE MAX4995AL ONLY.

1µF

IN

MAX4995A/
MAX4995AF/
MAX4995AL/

MAX4995B/

MAX4995C

GND

OUT

N.C.

1µF

LOAD

MAX4995A/AF/AL/MAX4995B/MAX4995C

50mA to 600mA Programmable

Current-Limit Switches

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.

Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________

13

© 2010 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.

Revision History

REVISION

NUMBER

0 11/08 Initial release. —

1 6/09 Corrected the Ordering Information/Selector Guide. 1, 11

2 2/10

REVISION

DATE

DESCRIPTION

• Added TDFN package information to the Ordering Information/Selector Guide,
Absolute Maximum Ratings, Pin Description, and Package Information sections.

• Added the TDFN pin conf iguration drawing to the Pin Configurations section.

PAGES

CHANGED

1, 2, 7, 12