Rainbow Electronics MAX4995 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 reverse-current 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 package and operate over the -40°C to +125°C
extended temperature range.

Applications

SDIO Ports

USB Ports

Notebook VGA Ports

GPS

Cell Phones

MP3 Players

UTCA/ATCA Platforms

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

MAX4995A/AF/AL/MAX4995B/MAX4995C

50mA to 600mA Programmable

Current-Limit Switches

________________________________________________________________

Maxim Integrated Products

1

Ordering Information/Selector Guide

19-4363; Rev 0; 11/08

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.

All devices operate over the -40°C to +125°C temperature range.
+Denotes a lead-free package.
*Future product. Contact factory for availability.
Ordering Information/Selector Guide continued at end of data sheet.

PART

PIN-

PACKAGE

ON POLARITY

OVERCURRENT

RESPONSE

SHORT-CIRCUIT

RESPONSE

TOP MARK

MAX4995AAUK+T* 6 SOT23 ActIve-High Autoretry Normal +ACNZ

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

MAX4995AFAUK+T*

6 SOT23 Active-High Autoretry Fast +ACOE

MAX4995AFAVB+T 10 UTQFN Active-High Autoretry Fast +AAR

MAX4995ALAUK+T*

6 SOT23 Active-Low Autoretry Normal +ACDA

Typical Operating Circuit appears at end of data sheet.

Pin Configurations

Pin Configurations continued at end of data sheet.

TOP VIEW

* ( ) FOR THE MAX4995AL ONLY.

IN

10 8

MAX4995A/MAX4995AF
MAX4995AL/MAX4995B

35

ON (ON)* GND

1.4mm x 1.8mm

N.C.

9

MAX4995C

4

UTQFN

OUT

7 OUT1IN

6 N.C.2FLAG

SETI

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

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

CONDITIONS

UNITS

SUPPLY OPERATION

Operating Voltage V

IN

1.7 5.5 V

Quiescent Current I

Q

I

OUT

= 0, switch on, V

IN

= 3.3V

µA

Latchoff Current

VIN = 3.3V, I

OUT

= 0 after an overcurrent

fault (MAX4995B)

815µA

Shutdown Forward Current I

SHDNVON

= 0, VON = VIN, V

IN

= 5.5V, V

OUT

= 0

5µA

Shutdown Reverse Current

V

ON

= 0, VON = VIN, V

IN

= 1.7V,

V

OUT

= 5.5V (current into OUT)

1µA

INTERNAL FET

Switch-On Resistance R

ON

VIN = 3.3V, I

OUT

lower than I

LIM

mΩ

Normalized Current-Limit Accuracy

I

LIM

= 50mA to 600mA, VIN - V

OUT

= 1V,

V

IN

= 3.3V (Note 3)

0.9 1 1.1 —

(R

SETI

+ 2.48) x I

LIM

Product

I

LIM

= 50mA to 600mA, VIN - V

OUT

= 1V,

V

IN

= 3.3V

V

Reverse Blocking Current

V

OUT

> V

IN

+ 300mV after reverse-current-

limit shutdown

10 µA

Reverse Blocking Threshold

V

OUT

= V

IN

+ 300mV, OUT falling until switch

turns on

35

mV

FLAG Assertion Drop Voltage
Threshold

V

FA

Increase (VIN - V

OUT

) drop until FLAG

asserts, I

OUT

limiting, VIN = 3.3V

mV

ON, ON INPUT

ON, ON Input Leakage I

LEAK

VON, VON = V

IN

or GND -1 +1 µA

ON, ON Input Logic-High Voltage V

IH

1.6 V

ON, ON Input Logic-Low Voltage V

IL

0.4 V

FLAG OUTPUT

FLAG Output Logic-Low Voltage I

SINK

= 1mA 0.4 V

FLAG Output Leakage Current V

IN

= V

FLAG

= 5.5V, FLAG deasserted 1 µA

SYMBOL

MIN TYP MAX

170 300

I

LATCH

I

RSHDN

26138 29042 31946

0.01

0.01

130 350

110 210

650

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.

t
t

RETRY

BLANK

I (mA)

2

R(k 2.48k

LIM

SETI

=

+

9042( )

)()

V

ΩΩ

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.)

PARAMETER

CONDITIONS

UNITS

DYNAMIC

Turn-On Time t

SS

V

IN

= 3.3V, C

OUT

= 1µF, RL = 20Ω, Figure 1,

(Note 4)

µs

Turn-Off Time t

OFF

S w i tch fr om on to off, V

I N

= 3.3V , C

OU T

= 1µF,

R

L

= 20Ω, Figure 1 (Note 4)

µs

5

Current-Limit Reaction Time t

LIM

V

IN

= 3.3V, R

SETI

=
578kΩ, output high
and then short-circuit
applied

MAX4995AF 1.5

µs

Blanking Time

(Note 5) 10

ms

Retry Time

ms

THERMAL PROTECTION

Thermal Shutdown

°C

Thermal-Shutdown Hysteresis 15 °C

t

SS

10%

90%

10%

90%

t

OFF

V

OUT

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

OFF

).

SYMBOL

t

BLANK

t

RETRY

MAX4995A/AL/B/C

M AX 4995A/M AX 4995AF/M AX 4995AL ( N ote 5) 320 723.2

MIN TYP MAX

120

120

16.3 22.6

+150

MAX4995A/AF/AL/MAX4995B/MAX4995C

50mA to 600mA Programmable
Current-Limit Switches

4 _______________________________________________________________________________________

CURRENT LIMIT

vs. SUPPLY VOLTAGE

MAX4995A toc01

SUPPLY VOLTAGE (V)

CURRENT LIMIT (mA)

2.0 3.02.5 4.5 5.03.5 4.0

290

295

300

305

310

315

285

1.5 5.5

MAX4995AL

NORMALIZED CURRENT LIMIT

vs. TEMPERATURE

MAX4995A toc02

TEMPERATURE (°C)

NORMALIZED CURRENT LIMIT

-25 5-10 20

0.950

0.975

1.000

1.050

0.925

1.025

1.075

1.100

0.900

-40 50 8065 95 11035 125

MAX4995AL

μ

μ

QUIESCENT SUPPLY CURRENT

vs. SUPPLY VOLTAGE

MAX4995A toc06

SUPPLY VOLTAGE (V)

QUIESCENT SUPPLY CURRENT (μA)

2.0 3.02.5 4.5 5.03.5 4.0

160

180

200

260

280

120

140

220

240

300

100

1.5 5.5

MAX4995A

Typical Operating Characteristics

(VIN= +3.3V, CIN= 1µF, C

OUT

= 1µF, R

SETI

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

CURRENT-LIMIT RESPONSE (MAX4995A)

APPLIED AT OUTPUT

10

s/div

CURRENT-LIMIT RESPONSE

4ms/div

MAX4995A toc03

SUDDEN SHORT

MAX4995A toc05

R

= 8Ω

LOAD

V

OUT

(2V/div)

I

OUT

(10A/div)

V

OUT

(2V/div)

I

OUT

(100mA/div)

CURRENT-LIMIT RESPONSE (MAX4995AF)

APPLIED AT OUTPUT

s/div

10

MAX4995A toc04

SUDDEN SHORT

V

OUT

(2V/div)

I

OUT

(10A/div)

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

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

Pin Description

PIN (UTQFN)

MAX4995AL

FUNCTION

1, 10 1, 10 IN

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

22

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.

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

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

4 4 GND Ground

5 5 SETI

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.

6, 9 6, 9 N.C. No Connect. Not internally connected.

7, 8 7, 8 OUT

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

MAX4995_

NAME

FLAG

MAX4995A/AF/AL/MAX4995B/MAX4995C

50mA to 600mA Programmable
Current-Limit Switches

8 _______________________________________________________________________________________

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).

Functional Diagram

MAX4995_/

MAX4995AF

MAX4995AL

ON ON

SWITCH
STATUS

0 1 Off

10On

Table 1. Switch Truth Table

MAX4995A/MAX4995AF/
MAX4995AL/MAX4995B/

MAX4995C

REVERSE­CURRENT

PROTECTION

IN

UVLO

N.C.

SOFT-START

ON (ON)*

*( ) FOR THE MAX4995AL ONLY.

BUFFER

BANDGAP

REFERENCE

THERMAL

SHUTDOWN

CONTROL

LOGIC

TIMING

CIRCUITRY

CURRENT

LIMIT

BUFFER

GND

OUT

FLAG

SETI

MAX4995A/AF/AL/MAX4995B/MAX4995C

50mA to 600mA Programmable

Current-Limit Switches

_______________________________________________________________________________________ 9

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

BLANK

t

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

10 ______________________________________________________________________________________

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.

P

VI t

tt

MAX

IN(MAX) OUT(MAX) BLANK

RETRY BLANK

=

××

+

C(F)

I (mA) t (ms)

V(

MAX

LIM BLANK(MIN)

IN

μ=

×

V)

R(k)

2

I(A

2.48 k

SETI

LIM

ΩΩ=

−

9042( )

)

()

V

m

R

SETI

(kΩ) TYPICAL CURRENT LIMIT (mA)

45.8 602

55.6 500

70.6 397

94.2 300

143 200

191 150

287 100

576 50

∞ (Open) 0

Table 2. Current Limit vs. Resistor Values

MAX4995A/AF/AL/MAX4995B/MAX4995C

50mA to 600mA Programmable

Current-Limit Switches

______________________________________________________________________________________ 11

Ordering Information/Selector Guide (continued)

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

+

Denotes a lead-free package.

*

Future product. Contact factory for availability.

PART

PIN-

PACKAGE

ON POLARITY

OVERCURRENT

RESPONSE

SHORT-CIRCUIT

RESPONSE

TOP MARK

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

MAX4995BAUK+T* 6 SOT23 Active-High Latchoff Normal +ACDB

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

MAX4995CAUK+T* 6 SOT23 Active-High Continuous Normal +ACOD

MAX4995CAVB+T 10-UTQFN Active-High Continuous Normal +AAQ

Pin Configurations (continued)

TOP VIEW

MAX4995A/MAX4995AF
MAX4995AL/MAX4995B

MAX4995C

6 FLAG1OUT

5IN2GND

4 ON (ON)*3SETI

1.6mm x 2.9mm
SOT23

* ( ) FOR THE MAX4995AL ONLY.

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.

12

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

© 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

Typical Operating Circuit

Chip Information

PROCESS: BiCMOS

Package Information

For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages

.

PACKAGE TYPE PACKAGE CODE DOCUMENT NO.

10 UTQFN V101A1CN+1

21-0028

6 SOT23 U6SN+1

21-0058

V

CC

V

IO

IN

FLAG

MAX4995A/

ON

µP

R

SETI

*( ) FOR THE MAX4995AL ONLY.

(ON*)

SETI

MAX4995AF/
MAX4995AL/

MAX4995B/

MAX4995C

GND

1µF

OUT

1µF

LOAD

N.C.