MAX890 [MAXIM]
1.2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown;
| 型号： | MAX890 |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 1.2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown |
| 文件： | 总8页 (文件大小：453K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-1146; Rev 4; 4/11
1.2A, Current-Limited, High-Side
P-Channel Switch with Thermal Shutdown
MAX890L
General Description
Features
The MAX890L smart, low-voltage, P-channel, MOSFET
power switch is intended for high-side load-switching
applications. This switch operates with inputs from
+2.7V to +5.5V, making it ideal for both +3V and +5V
systems. Internal current-limiting circuitry protects the
input supply against overload. Thermal-overload pro-
tection limits power dissipation and junction tempera-
tures.
♦ +2.7V to +5.5V Input Range
♦ Programmable Current Limit
♦ Low Quiescent Current
10µA (typ) at V = +3.3V
IN
0.1µA (typ) with Switch Off
♦ Thermal Shutdown
The MAX890L’s maximum current limit is 1.2A. The cur-
rent limit through the switch is programmed with a
resistor from SET to ground. The quiescent supply cur-
rent is a low 10µA. When the switch is off, the supply
current decreases to 0.1µA.
♦ FAULT Indicator Output
♦ 0.09Ω (typ) On-Resistance
The MAX890L is available in an 8-pin SO package.
Applications
Ordering Information
PCMCIA Slots
PIN-
PACKAGE
CURRENT
LIMIT
PART
TEMP RANGE
Access Bus Slots
Portable Equipment
MAX890LC/D
0°C to +70°C Dice**
-40°C to +85°C 8 SO
1.2A
1.2A
1.2A
MAX890LESA+
MAX890LESA/V+ -40°C to +85°C 8 SO
*To order this unit in tape and reel, add (T) to the end of the
part number.
**Dice are tested at T = +25°C.
A
+Denotes a lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part.
Typical Operating Circuit
Pin Configuration
TOP VIEW
INPUT
IN
OUT
OUT
ON
OUTPUT
0.1μF
+
FAULT
OUT
IN
IN
1
2
3
4
8
7
6
5
IN
MAX890L
100kΩ
MAX890L
FAULT
GND
ON/OFF
OUT
ON
1μF
SET
SET
GND
R
SET
SO
________________________________________________________________ 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.
1.2A, Current-Limited, High-Side
P-Channel Switch with Thermal Shutdown
ABSOLUTE MAXIMUM RATINGS
IN to GND ................................................................-0.3V to +6V
Operating Temperature Range
ON, FAULT to GND .................................................-0.3V to +6V
MAX890LESA ....................................................-40°C to +85°C
Storage Temperature Range ........................... -65°C to +150°C
Lead Temperature (soldering, 10s) . ...............................+300°C
Soldering Temperature (reflow) .......................................+260°C
SET, OUT to GND ...................................... -0.3V to (V + 0.3V)
IN
Maximum Continuous Switch Current ..................................1.5A
Continuous Power Dissipation (T = +70°C)
A
SO (derate 5.88mW/°C above +70°C) ..........................471mW
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.
MAX890L
ELECTRICAL CHARACTERISTICS
(V = +3V, T = 0°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.)
IN
A
A
PARAMETER
CONDITIONS
MIN
2.7
TYP
MAX
5.5
UNITS
V
Operating Voltage
Quiescent Current
Off-Supply Current
Off-Switch Current
Undervoltage Lockout
13
0.03
0.04
2.4
20
µA
µA
µA
V
V
IN
= 5V, ON = GND, I
= 0A
OUT
1
ON = IN, V = V
= 5.5V
IN
OUT
15
ON = IN, V = 5.5V, V
= 0V
OUT
IN
Rising edge, 1% hysteresis
2.0
2.6
V
V
V
= 4.5V
= 3.0V
75
130
150
1.302
IN
On-Resistance
mΩ
90
IN
Current-Limit-Amplifier Threshold
Maximum Output Current Limit
required to turn the switch off (Note 1)
1.178
970
1.240
1.2
V
A
SET
I
to I
Current Ratio
I
= 500mA, V > 1.6V
OUT
1110
1300
0.8
A/A
V
OUT
SET
OUT
V
V
V
V
V
I
= 2.7V to 5.5V
= 2.7V to 3.6V
= 4.5V to 5.5V
= 5.5V
ON Input Low Voltage
ON Input High Voltage
ON Input Leakage Current
IN
IN
IN
2.0
2.4
V
0.01
0.5
1
3
µA
µA
V
ON
I
Bias Current
= 1.24V, I
= 1mA, V
= 0A; V = V
OUT IN OUT
SET
SET
= 1.4V
= 1V
SET
0.4
1
FAULT Logic Output Low Voltage
FAULT Logic Output High Leakage Current
Slow-Current-Loop Response Time
Fast-Current-Loop Response Time
SINK
SET
V
= 5.5V, V
0.05
5
µA
µs
µs
FAULT
20% current overdrive, V
= 5V
CC
2
V
IN
V
IN
V
IN
= 5V, I
= 3V, I
= 5V
= 500mA
= 500mA
120
185
5
200
OUT
OUT
Turn-On Time
Turn-Off Time
µs
µs
2
2
_______________________________________________________________________________________
1.2A, Current-Limited, High-Side
P-Channel Switch with Thermal Shutdown
MAX890L
ELECTRICAL CHARACTERISTICS
(V = +3V, T = -40°C to +85°C, unless otherwise noted.) (Note 2)
IN
A
PARAMETER
CONDITIONS
MIN
3.0
TYP
MAX
5.5
UNITS
V
Operating Voltage
Quiescent Current
Off-Supply Current
Off-Switch Current
Undervoltage Lockout
50
µA
µA
µA
V
V
IN
= 5V, ON = GND, I
= 0A
OUT
2.2
ON = IN, V = V
= 5.5V
IN
OUT
15
ON = IN, V = 5.5V, V
= 0V
OUT
IN
Rising edge, 1% hysteresis
2.0
2.9
V
V
V
= 4.5V
= 3.0V
130
150
1.34
1390
0.4
IN
On-Resistance
mΩ
IN
Current-Limit-Amplifier Threshold
required to turn the switch off (Note 1)
1.14
925
V
A/A
V
SET
OUT
SINK
I
to I
Current Ratio
I
I
= 500mA, V
= 1mA, V
> 1.6V
OUT
SET
OUT
= 1.4V
FAULT Logic Output Low Voltage
Turn-On Time
SET
V
V
= 5V
200
20
µs
µs
IN
Turn-Off Time
= 5V
1
IN
Note 1: Tested with I
= 100mA and V
raised until V - V
≥ 0.8V.
OUT
SET
IN
OUT
Note 2: Specifications to -40°C are guaranteed by design; not production tested.
_______________________________________________________________________________________
3
1.2A, Current-Limited, High-Side
P-Channel Switch with Thermal Shutdown
__________________________________________Typical Operating Characteristics
(T = +25°C, unless otherwise noted.)
A
QUIESCENT CURRENT
vs. INPUT VOLTAGE
QUIESCENT CURRENT
vs. TEMPERATURE
OFF-SUPPLY CURRENT
vs. TEMPERATURE
14
14
100
10
1
ON = GND
12
13
12
11
I
= 0A
OUT
V
= 5V
= 3V
IN
MAX890L
10
8
V
IN
6
10
4
9
8
7
0.1
2
0
0.01
0
1
2
3
4
5
6
-40 -20
0
20
40
60
80
100
-40 -20
0
20
40
60
80 100
INPUT VOLTAGE (V)
TEMPERATURE (°C)
TEMPERATURE (°C)
I
/I RATIO
NORMALIZED ON-RESISTANCE
vs. TEMPERATURE
OFF-SWITCH CURRENT
vs. TEMPERATURE
OUT SET
vs. I
LIMIT
1400
1000
100
10
1.3
I
= 1/2I
LIMIT
OUT
1200
1000
800
1.2
1.1
1.0
600
0.9
1
400
200
0
0.8
0.7
0.6
0.1
0.01
0
20
40
60
80 100 120 140
(%)
-40 -20
0
20
40
60
80 100
-40 -20
0
20
40
60
80
100
I
TEMPERATURE (°C)
TEMPERATURE (°C)
LIMIT
NORMALIZED OUTPUT CURRENT
vs. OUTPUT VOLTAGE
TURN-ON TIME
vs. TEMPERATURE
TURN-OFF TIME
vs. TEMPERATURE
1.2
1.0
0.8
0.6
0.4
0.2
0
260
240
220
8
I
= I
LOAD LIMIT
I
= I
LOAD LIMIT
I
7
6
5
4
3
LIMIT
V
= 3V
IN
200
180
V
V
= 5V
= 3V
IN
160
140
120
100
80
IN
V
= 5V
IN
2
1
V
= 5V
IN
60
0
-40 -20
0
20
40
60
80
100
0
1
2
3
4
5
6
-40 -20
0
20
40
60
80
100
OUTPUT VOLTAGE (V)
TEMPERATURE (°C)
TEMPERATURE (°C)
4
_______________________________________________________________________________________
1.2A, Current-Limited, High-Side
P-Channel Switch with Thermal Shutdown
MAX890L
____________________________Typical Operating Characteristics (continued)
(T = +25°C, unless otherwise noted.)
A
OUTPUT OVERLOAD
(SLOW LOOP RESPONSE)
OUTPUT SHORT-CIRCUIT
(FAST LOOP RESPONSE)
MAX890 toc10
MAX890 toc11
A
B
5V
A
B
5V
0A
0V
C
C
0V, 0A
2μs/div
= 0.1μF
A: V , 1V/div, AC-COUPLED
2μs/div
= 0.1μF
A: V , 1V/div, AC-COUPLED
B: I , 1A/div
OUT
C: V , 2V/div
OUT
B: I , 5A/div
OUT
C: V , 2V/div
OUT
C
= 100μF, C
IN
C
= 100μF, C
IN
IN
OUT
IN
OUT
LOAD-TRANSIENT RESPONSE
SWITCH TURN-ON TIME
MAX890 toc12
MAX890 toc13
A
B
A
B
0A
0V
5ms/div
20μs/div
V
A: I
= 5V
IN
B: V
RIPPLE,
OUT
V
= 5V, I
= I
OUT LIMIT
IN
= 0mA TO 750mA,
OUT
200mV/div, AC COUPLED
A: V , 2V/div
B: V , 2V/div
OUT
ON
0.5A/div
SWITCH TURN-OFF TIME
MAX890 toc14
A
0V
B
0V
2μs/div
V
IN
= 5V, I
= I
OUT LIMIT
A: V , 2V/div
ON
B: V , 2V/div
OUT
_______________________________________________________________________________________
5
1.2A, Current-Limited, High-Side
P-Channel Switch with Thermal Shutdown
Pin Description
PIN
1, 2
3
NAME
IN
FUNCTION
Input. P-channel MOSFET source. Bypass IN with a 1μF capacitor to ground.
Active-Low Switch On Input. A logic low turns the switch on.
Ground
ON
4
GND
Set Current-Limit Input. A resistor from SET to ground sets the current limit for the switch.
= 1.38 x 103/I
where I is the desired current limit in amperes.
5
6, 7
8
SET
OUT
R
SET
LIMIT,
LIMIT
MAX890L
Switch Output. P-channel MOSFET drain. Bypass OUT with a 0.1μF capacitor to ground.
Fault-Indicator Output. This open-drain output goes low when in current limit or when the die temperature
exceeds +135°C.
FAULT
Detailed Description
The MAX890L P-channel MOSFET power switch limits
output current to a programmed level. When the output
current is increased beyond the programmed current
P
OUT
IN
MAX890L
limit, or 1.2A (I
), the current also increases through
MAX
FAULT
P
the replica switch (I
/1110) and through R
SET
OUT
(Figure 1). The current-limit error amplifier compares
the voltage across R to the internal +1.24V refer-
N
SET
REPLICA
AMPLIFIER
ence and regulates the current back to the lesser of the
programmed limit (I ) or 1.2A.
ON
LIMIT
This switch is not bidirectional; therefore, the input volt-
age must be higher than the output voltage.
P
SET
Setting the Current Limit
ON
CURRENT-LIMIT
AMPLIFIER
The MAX890L features internal current-limiting circuitry
R
SET
with a maximum programmable value (I
) of 1.2A.
MAX
1.24V
For best performance, set the current limit (I
)
LIMIT
between 0.2 I
≤ I
≤ I
. This current limit
MAX
LIMIT
MAX
remains in effect throughout the input supply-voltage
range.
HOT
GND
CONTROL
CIRCUITRY
ON
Program the current limit with a resistor (R
SET to ground (Figure 2) as follows:
) from
SET
I
= I
/ 1110
SET
LIMIT
3
R
= 1.24V / I = 1.38 x 10 / I
8 LIMIT
SET
Figure 1. Functional Diagram
where I
is the desired current limit.
LIMIT
For a high dV /dt during an output short-circuit condi-
DS
Short-Circuit Protection
tion, the switch turns off and disconnects the input supply
from the output. The current-limiting amplifier then slow-
ly turns the switch on with the output current limited to
The MAX890L is a short-circuit-protected switch. In the
event of an output short circuit or current-overload con-
dition, the current through the switch is limited by the
1.5 x I
. When the fault condition is removed, the
LIMIT
internal current-limiting error amplifier to 1.5 x I
.
LIMIT
current limit is set back to I
. Refer to the Output
LIMIT
When the fault condition is removed, the replica error
amplifier sets the current limit back to I
Short-Circuit Fast-Loop Response and Output Overload
Slow-Loop Response in the Typical Operating
Characteristics.
.
LIMIT
6
_______________________________________________________________________________________
1.2A, Current-Limited, High-Side
P-Channel Switch with Thermal Shutdown
MAX890L
Output Capacitor
Connect a 0.1µF capacitor from OUT to GND. One
function of this capacitor is to prevent inductive para-
sitics from pulling OUT negative during turn-off.
MAX890L
Layout and Thermal-Dissipation
SET
Consideration
To take full advantage of the switch-response time to
R
SET
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
(no more than 5mm).
GND
Under normal operating conditions, the package can
dissipate and channel heat away. Calculate the maxi-
mum power as follows:
Figure 2. Setting the Current Limit
P = I2
x R
ON
Thermal Shutdown
LIMIT
The MAX890L features thermal shutdown. The switch
turns off when the junction temperature exceeds
+135°C. Once the device cools by 10°C, the switch
turns back on. If the fault short-circuit condition is not
removed, the switch cycles on and off, resulting in a
pulsed output.
where R
is the on-resistance of the switch.
ON
When the output is short circuited, the voltage drop
across the switch equals the input supply. Hence, the
power dissipated across the switch increases, as does
the die temperature. If the fault condition is not
removed, the thermal-overload-protection circuitry turns
the switch off until the die temperature falls by 10°C. A
ground plane in contact with the device helps dissipate
additional heat.
Fault Indicator
The MAX890L provides a fault output (FAULT). This
open-drain output goes low when in current limit or
when the die temperature exceeds +135°C. A 100kΩ
pull-up resistor from FAULT to IN provides a logic-
control signal.
Package Information
For the latest package outline information and land patterns
(footprints), 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.
Applications Information
Input Capacitor
To limit the input voltage drop during momentary output
short-circuit conditions, connect a capacitor from IN to
GND. A 1µF ceramic capacitor is adequate for most
applications; however, higher capacitor values further
reduce the voltage drop at the input.
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
21-0041
LAND
PATTERN NO.
8 SO
S8+5
90-0096
_______________________________________________________________________________________
7
1.2A, Current-Limited, High-Side
P-Channel Switch with Thermal Shutdown
Revision History
REVISION REVISION
PAGES
CHANGED
DESCRIPTION
NUMBER
DATE
Added the MAX890LESA/V+ part number to the Ordering Information, deleted the Chip
Information section
4
4/11
1, 7
MAX890L
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.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2011 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
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