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PDF MAX4995B Data sheet ( Hoja de datos )
| Número de pieza | MAX4995B | |
| Descripción | 50mA to 600mA Programmable Current-Limit Switches | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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19-4363; Rev 2; 2/10
www.DataSheet4U.com
50mA to 600mA Programmable
Current-Limit Switches
General Description
The MAX4995A/MAX4995AF/MAX4995AL/MAX4995B/
MAX4995C programmable current-limit switches fea-
ture 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/out-
put) 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, 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
SDIO Ports
USB Ports
Notebook VGA Ports
GPS
Applications
Cell Phones
MP3 Players
UTCA/ATCA Platforms
Ordering Information/Selector Guide
PART
PIN-PACKAGE
ON POLARITY
MAX4995AAUT+T* 6 SOT23
Active-High
MAX4995AAVB+T 10 UTQFN
Active-High
MAX4995AATA+T 8 TDFN-EP**
Active-High
MAX4995AFAUT+T* 6 SOT23
Active-High
MAX4995AFAVB+T 10 UTQFN
Active-High
MAX4995AFATA+T* 8 TDFN-EP**
Active-High
MAX4995ALAUT+T* 6 SOT23
Active-Low
MAX4995ALAVB+T 10 UTQFN
Active-Low
MAX4995ALATA+T* 8 TDFN-EP**
Active-Low
MAX4995BAUT+T* 6 SOT23
Active-High
MAX4995BAVB+T 10 UTQFN
Active-High
MAX4995BATA+T* 8 TDFN-EP**
Active-High
MAX4995CAUT+T* 6 SOT23
Active-High
MAX4995CAVB+T 10 UTQFN
Active-High
MAX4995CATA+T* 8 TDFN-EP**
Active-High
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.
OVERCURRENT
RESPONSE
Autoretry
Autoretry
Autoretry
Autoretry
Autoretry
Autoretry
Autoretry
Autoretry
Autoretry
Latchoff
Latchoff
Latchoff
Continuous
Continuous
Continuous
SHORT-CIRCUIT
RESPONSE
Normal
Normal
Normal
Fast
Fast
Fast
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
TOP MARK
+ACNZ
+AAM
+ABL
+ACOE
+AAR
+ACO
+ACDA
+AAN
+ABM
+ACDB
+AAO
+ABN
+ACOD
+AAQ
+ABP
Typical Operating Circuit appears at end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
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.
1 page  
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50mA to 600mA Programmable
Current-Limit Switches
Typical Operating Characteristics (continued)
(VIN = +3.3V, CIN = 1µF, COUT = 1µF, RSETI = 94.2kΩ, TA = +25°C, unless otherwise noted.)
QUIESCENT SUPPLY LIMIT
vs. TEMPERATURE
260
250 VIN = 5V
240
230
220
210
200
190
180 VIN = 3.3V
170
160
150 MAX4995AL
140
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
SHUTDOWN REVERSE CURRENT
vs. TEMPERATURE
225
MAX4995C
200 VOUT = 5.5V
175
150
125 VIN = 5V
100
75
50 VIN = 1.7V
25
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
2.50
MAX4995AL
2.25
2.00
1.75
1.50
1.25 VIN = 5V
1.00
0.75
0.50
VIN = 3.3V
0.25
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
LATCHOFF CURRENT
vs. TEMPERATURE
20
MAX4995B
18 VIN = 5V
16
14
12 VIN = 3.3V
10
8
6
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
SHUTDOWN FORWARD CURRENT
vs. TEMPERATURE
80
MAX4995C
70
60
50
40 VIN = 5V
30
20
VIN = 1.7V
10
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
NORMALIZED ON-RESISTANCE
vs. SUPPLY VOLTAGE
1.040
1.035
1.030
MAX4995C
IOUT < ILIM
1.025
1.020
1.015
1.010
1.005
1.000
0.995
0.990
0.985
0.980
1.7 2.2 2.7 3.2 3.7 4.2 4.7 5.2
SUPPLY VOLTAGE (V)
NORMALIZED ON-RESISTANCE
vs. TEMPERATURE
1.5
MAX4995C
1.4 VIN = 3.3V
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
SWITCH TURN-ON TIME
vs. TEMPERATURE
180
MAX4995C
170 ILOAD = 10mA
160
150
VIN = 5V
140
130
120 VIN = 3.3V
110
100
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
SWITCH TURN-OFF TIME
vs. TEMPERATURE
1.6
MAX4995C
1.5 ILOAD = 10mA
1.4
1.3 VIN = 5V
1.2
1.1
1.0
0.9
0.8 VIN = 3.3V
0.7
0.6
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
_______________________________________________________________________________________ 5
5 Page 
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50mA to 600mA Programmable
Current-Limit Switches
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 lim-
its set by different resistor values at SETI. Shorting SETI
to ground asserts FLAG.
Use the following formula to calculate the current limit:
RSETI (kΩ)
=
29042(V)
ILIM (mA)
−
2.48(kΩ)
Using an RSETI 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.
Table 2. Current Limit vs. Resistor Values
RSETI (kΩ)
45.8
55.6
70.6
94.2
143
191
287
576
∞ (Open)
TYPICAL CURRENT LIMIT (mA)
602
500
397
300
200
150
100
50
0
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 (CMAX) value that
can be connected to OUT using the following formula:
CMAX
(μF )
=
ILIM
(mA)
×
t BLANK(MIN)
VIN (V)
(ms
)
For example, for VIN = 3.3V, tBLANK(MIN) = 10ms, and
ILIM = 300mA, CMAX 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 short-
circuit 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 maxi-
mum 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:
PMAX
=
VIN(MAX) × IOUT(MAX) × tBLANK
tRETRY + tBLANK
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.
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet MAX4995B.PDF ] | |
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