MAX895LESA-T [MAXIM]
Analog IC ; 模拟IC\n
| 型号： | MAX895LESA-T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Analog IC
|
| 文件： | 总8页 (文件大小：100K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-1153; Rev 0; 10/96
Du a l, Cu rre n t -Lim it e d , Hig h -S id e P -Ch a n n e l
S w it c h e s w it h Th e rm a l S h u t d o w n
4/MAX895L
_______________Ge n e ra l De s c rip t io n
____________________________Fe a t u re s
♦ +2.7V to +5.5V Input Range
The MAX894L/MAX895L s ma rt, d ua l, low-volta g e ,
P-channel, MOSFET power switches are intended for
high-side load-switching applications. These switches
operate with inputs from +2.7V to +5.5V, making them
ideal for both 3V and 5V systems. Internal current-
limiting c irc uitry p rote c ts the inp ut s up p ly a g a ins t
overload. Thermal-overload protection limits power dis-
sipation and junction temperature.
♦ Programmable Current Limits
♦ Low Supply Current:
16µA I at V = 3.3V
Q
IN
0.1µA with Switch Off
♦ Thermal Shutdown
The MAX894L/MAX895L’s maximum current limits are
500mA a nd 250mA, re s p e c tive ly. The c urre nt limit
through the switches is programmed with resistors from
SET A/SET B to ground. When the switches are on, the
q uie s c e nt s up p ly c urre nt is a low 16µA. Whe n the
switches are off, the supply current decreases to 0.1µA.
______________Ord e rin g In fo rm a t io n
The MAX894L/MAX895L are available in an 8-pin SO
package.
TEMP.
PIN-
CURRENT
LIMIT
PART*
RANGE
PACKAGE
MAX894LC/D
0°C to +70°C
Dice**
8 SO
500mA
500mA
250mA
250mA
MAX894LESA -40°C to +85°C
MAX895LC/D 0°C to +70°C
MAX895LESA -40°C to +85°C
________________________Ap p lic a t io n s
Dice**
8 SO
PCMCIA Slots
Access Bus Slots
Portable Equipment
*To order these units in tape and reel, add (-T) to the end of the
part number.
**Dice are tested at T = +25°C.
A
__________Typ ic a l Op e ra t in g Circ u it
__________________P in Co n fig u ra t io n
TOP VIEW
OUTPUT A
OUT A
OUT B
SET A
ONB
IN
ON/OFF
0.1µF
OUTPUT B
INPUT
OUT A
OUT B
SET A
ONA
ONB
IN
1
2
3
4
8
7
6
5
MAX894L
MAX895L
0.1µF
1µF
MAX894L
MAX895L
SET B
GND
SET B
R
SET A
R
SET B
SO
ONA
GND
ON/OFF
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
Du a l, Cu rre n t -Lim it e d , Hig h -S id e P -Ch a n n e l
S w it c h e s w it h Th e rm a l S h u t d o w n
ABSOLUTE MAXIMUM RATINGS
IN to GND...................................................................-0.3V to 6V
Continuous Power Dissipation (T = +70°C)
A
ONA, ONB to GND.....................................................-0.3V to 6V
SO (derate 5.88mW/°C above +70°C) .......................471mW
Operating Temperature Range
SET A, SET B, OUT A, OUT B to GND ........-0.3V to (V + 0.3V)
IN
Maximum Continuous Switch Current
MAX894L ..........................................................................0.75A
MAX895L ........................................................................0.375A
MAX89_LESA .................................................-40°C to +85°C
Storage Temperature Range ...............................-65°C to+150°C
Lead Temperature (soldering, 10sec)..............................+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 = 3V, T = 0°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.)
IN
A
A
PARAMETER
CONDITION
MIN
TYP
MAX
5.5
30
UNITS
Operating Voltage
Quiescent Current
Off-Supply Current
Off-Switch Current
Undervoltage Lockout
2.7
V
µA
µA
µA
V
18
0.03
0.04
2.4
V
= 5V, ONA = ONB = GND, I
= I
= 0
IN
OUT A
OUT B
1
ONA = ONB = IN, V = V
= V
= 5.5V
IN
OUT A
OUT B
4/MAX895L
3
ONA = ONB = IN, V = 5.5V, V
= V
= 0
IN
OUT A
OUT B
Rising edge, 1% hysteresis
2.0
2.6
225
420
300
500
1.302
MAX894L
MAX895L
MAX894L
MAX895L
120
V
IN
= 4.5V
= 3.0V
250
On-Resistance
mΩ
150
V
IN
300
Current-Limit-Amplifier Threshold
Maximum Output Current
V
SET
required to turn the switch off (Note 1)
1.178
1.240
500
V
MAX894L
MAX895L
mA
250
MAX894L, I
MAX895L, I
= 250mA
= 125mA
945
910
1085
1050
1270
1235
0.8
OUT
I
to I
Current Ratio
V = 1.6V to 2.8V
OUT
A/A
V
OUT
SET
OUT
V
= 2.7V to 5.5V
= 2.7V to 3.6V
= 4.5V to 5.5V
ONA, ONB Input Low Voltage
ONA, ONB Input High Voltage
ONA, ONB Input Leakage
IN
V
IN
2.0
2.4
V
V
IN
µA
0.01
0.5
1
3
3
V
ONA
= V
= 5.5V
ONB
V
SET A
= 1.24V, ONA = 0, ONB = V , I
= 0
IN
OUT A
µA
I
I
Bias Current
SETA, SETB
V
SET B
= 1.24V, ONB = 0, ONA = V , I
= 0
0.5
5
IN
OUT B
µs
µs
Slow-Current-Loop Response Time
Fast-Current-Loop Response Time
20% current overdrive, V = 5V
CC
2
V
= 5V, I
= 3V, I
= 250mA (MAX894L), 125mA (MAX895L)
= 250mA (MAX894L), 125mA (MAX895L)
100
150
1.2
200
IN
OUT
µs
µs
Turn-On Time
Turn-Off Time
V
IN
OUT
0.8
20
Note 1: Tested with I
= 50mA for the MAX894L and 25mA for the MAX895L, and V
raised until V - V ≥ 0.8V.
OUT
OUT
SET
IN
2
_______________________________________________________________________________________
Du a l, Cu rre n t -Lim it e d , Hig h -S id e P -Ch a n n e l
S w it c h e s w it h Th e rm a l S h u t d o w n
4/MAX895L
ELECTRICAL CHARACTERISTICS (Note 2)
(V = 3V, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.)
IN
A
A
PARAMETER
CONDITION
MIN
TYP
MAX
5.5
UNITS
Operating Voltage
Quiescent Current
Off-Supply Current
Off-Switch Current
Undervoltage Lockout
3.0
V
µA
µA
µA
V
50
V
IN
= 5V, ONA = ONB = GND, I
= I
= 0
OUT A
OUT B
2.2
ONA = ONB = IN, V = V
= V
= 5.5V
IN
OUT A
OUT B
8
ONA = ONB = IN, V = 5.5V, V
= V
= 0
IN
OUT A
OUT B
Rising edge, 1% hysteresis
2.0
2.9
MAX894L
MAX895L
MAX894L
MAX895L
250
420
300
500
1.34
1360
1315
V
= 4.5V
= 3.0V
IN
mΩ
On-Resistance
V
IN
Current-Limit-Amplifier Threshold
V
SET_
required to turn the switch off (Note 1)
1.14
910
880
V
MAX894L, I
= 250mA
= 125mA
OUT
V
= 1.24V,
= 1.6V to 2.8V
SET
I
to I
Current Ratio
A/A
OUT
SET
V
OUT
MAX895L, I
OUT
µs
µs
Turn-On Time
Turn-Off Time
V
IN
= 5V
200
20
0.25
Note 2: Specifications to -40°C are guaranteed by design, not production tested.
_______________________________________________________________________________________
3
Du a l, Cu rre n t -Lim it e d , Hig h -S id e P -Ch a n n e l
S w it c h e s w it h Th e rm a l S h u t d o w n
__________________________________________Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s
(Typical Operating Circuit, T = +25°C, unless otherwise noted.)
A
QUIESCENT CURRENT
vs. TEMPERATURE
QUIESCENT CURRENT
vs. INPUT VOLTAGE
OFF-SUPPLY CURRENT
vs. TEMPERATURE
24
22
20
28
24
20
0.07
0.06
0.05
ONA = ONB = GND
= I = 0
I
OUT A OUT B
16
12
8
0.04
0.03
0.02
0.01
0
V
= 5V
= 3V
IN
18
16
14
12
V
IN
4
0
-40 -20
0
20
40
60
80 100
0
1
2
3
4
5
6
-40 -20
0
20 40
60 80 100
4/MAX895L
TEMPERATURE (°C)
INPUT VOLTAGE (V)
TEMPERATURE (°C)
OFF-SWITCH CURRENT
vs. TEMPERATURE
NORMALIZED ON-RESISTANCE
vs. TEMPERATURE
I
/I vs. I
LIMIT
OUT SET
1600
1400
0.07
0.06
0.05
1.3
1.2
I
= 1/2 I
LIMIT
OUT
1200
1000
1.1
1.0
0.04
0.03
0.02
0.01
0
800
600
400
200
0
0.9
0.8
0.7
0.6
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
LIMIT
TEMPERATURE (°C)
TEMPERATURE (°C)
NORMALIZED OUTPUT CURRENT
vs. OUTPUT VOLTAGE
TURN-ON TIME
vs. TEMPERATURE
TURN-OFF TIME
vs. TEMPERATURE
7
6
5
1.4
1.2
1.0
260
240
I
= I
LOAD LIMIT
I
= I
LOAD LIMIT
V
IN
= 5V
220
V
= 5V
= 3V
I
IN
LIMIT
200
180
160
4
3
2
0.8
0.6
0.4
0.2
0
V
= 3V
= 5V
IN
V
IN
140
120
100
V
IN
1
0
80
60
0
1
2
3
4
5
6
-40 -20
0
20
40
60 80 100
-40 -20
0
20
40
60 80 100
OUTPUT VOLTAGE (V)
TEMPERATURE (°C)
TEMPERATURE (°C)
4
_______________________________________________________________________________________
Du a l, Cu rre n t -Lim it e d , Hig h -S id e P -Ch a n n e l
S w it c h e s w it h Th e rm a l S h u t d o w n
4/MAX895L
____________________________Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s (c o n t in u e d )
(Typical Operating Circuit, T = +25°C, unless otherwise noted.)
A
CURRENT-LIMIT RESPONSE
(MAX894L, R = 0.7Ω)
CURRENT-LIMIT RESPONSE
L
(MAX894L, R = 1Ω)
L
5V
A
5V
A
B
B
C
0A
C 0V
0A
0V
MAX894/895/896 TOC-10
MAX894/895/896 TOC-9
1µs/div
2µs/div
B: I
C: V 5V/div
2A/div
C
= 47µF, C = 0.1µF
OUT
OUT,
IN
C
= 47µF, C = 0.1µF
B: I
C: V 5V/div
OUT,
2A/div
IN
OUT
OUT,
A: V 500mV/div, AC coupled
OUT,
IN,
A: V 500mV/div, AC coupled
IN,
LOAD-TRANSIENT RESPONSE
(MAX894L)
A
0A
0V
B
MAX494/495/496 TOC-13
2ms/div
V = 5V
A: I = 0 to 500mA, 0.2A/div
OUT
IN
SWITCH TURN-ON TIME
SWITCH TURN-OFF TIME
B: V RIPPLE, 200mV/div, AC COUPLED
OUT
A
B
A
0V
B
0V
MAX894/895/896 TOC-11
MAX894/895/896 TOC-12
20µs/div
2µs/div
V = 5V, I = I
IN
OUT LIMIT
V = 5V, I = I
IN
OUT LIMIT
A: V , 2V/div
ON
A: V , 2V/div
ON
B: V , 2V/div
OUT
B: V , 2V/div
OUT
_______________________________________________________________________________________
5
Du a l, Cu rre n t -Lim it e d , Hig h -S id e P -Ch a n n e l
S w it c h e s w it h Th e rm a l S h u t d o w n
______________________________________________________________P in De s c rip t io n
PIN
1
NAME
OUT A
OUT B
FUNCTION
Switch A Output. P-channel MOSFET drain. Bypass OUT A with a 0.1µF capacitor to ground.
Switch B Output. P-channel MOSFET drain. Bypass OUT B with a 0.1µF capacitor to ground.
2
Set Current-Limit Input. A resistor from SET A to ground sets the current limit for switch A. See Setting the
Current Limit section.
3
SET A
4
5
Active-Low Switch A On Input. A logic low turns switch A on.
Ground
ONA
GND
Set Current-Limit Input. A resistor from SET B to ground sets the current limit for switch B. See Setting the
Current Limit section.
6
SET B
Input, Switches A and B. P-channel MOSFET source. Bypass IN with a 1µF capacitor to ground.
7
8
IN
Active-Low Switch B On Input. A logic low turns switch B on.
ONB
4/MAX895L
P
OUT A
OUT B
IN
P
P
P
REPLICA
AMPLIFIER B
MAX894L
MAX895L
ON
ON
REPLICA
P
AMPLIFIER A
P
SET B
SET A
ON
R
SET B
R
SET A
1.24V
CURRENT-LIMIT
AMPLIFIER B
ON
1.24V
CURRENT-LIMIT
AMPLIFIER A
ONB
GND
ONA
CONTROL
CIRCUITRY
Figure 1. Functional Diagram
6
_______________________________________________________________________________________
Du a l, Cu rre n t -Lim it e d , Hig h -S id e P -Ch a n n e l
S w it c h e s w it h Th e rm a l S h u t d o w n
4/MAX895L
_______________De t a ile d De s c rip t io n
The MAX894L/MAX895L P-c ha nne l MOSFET powe r
switches limit output current to a user-programmed
SET
level. When the output current is increased beyond the
R
SET
MAX894L
MAX895L
set current level, the current also increases through the
replica switch (I /1050) (MAX895) and through R
OUT
SET
GND
(Figure 1). The current-limit error amplifier compares
the voltage across R to the internal 1.24V reference,
SET
and regulates the current back to the lesser of the pro-
grammed current limit (I ) or the maximum current
LIMIT
Figure 2. Setting the Current Limit
limit (I ).
MAX
__________Ap p lic a t io n s In fo rm a t io n
These switches are not bidirectional; therefore, the
input voltage must be higher than the output voltage.
In p u t Ca p a c it o r
To limit input voltage drop during momentary output
short-circuit conditions, place a capacitor from IN to
GND. A 1µF ceramic capacitor is adequate for most
applications; however, higher capacitor values further
reduce voltage drop at the input.
S e t t in g t h e Cu rre n t Lim it
The MAX894L/MAX895L feature internal current-limiting
circuitry with maximum programmable values (I
) of
MAX
500mA, a nd 250mA, re s p e c tive ly. For b e s t p e rfor-
mance, set the current limit (I ) between 0.2I
≤
MAX
LIMIT
I
≤ I
. This c urre nt limit re ma ins in e ffe c t
LIMIT
MAX
Ou t p u t Ca p a c it o r
Conne c t a 0.1µF c a p a c itor from OUT to GND. This
capacitor prevents inductive parasitics from pulling
OUT negative during turn-off.
throughout the input supply-voltage range.
Program the current limit with a resistor (R
nected from SET_ to ground (Figure 2) as follows:
) con-
SET_
I
R
= I / I
SET
LIMIT RATIO
La yo u t a n d Th e rm a l-Dis s ip a t io n
Co n s id e ra t io n
= 1.24V / I
= (1.24V x I
) / I
SET
SET
RATIO LIMIT
where I
and I
is the desired current limit for either switch
LIMIT
To take full advantage of the switch-response time to
output short-circuit conditions, it is very important to
keep all traces as short as possible, reducing the effect
of undesirable parasitic inductance. Place input and
output capacitors as close as possible to the device
(no more than 5mm).
is the I
to I
current ratio (1085mA for
RATIO
OUT
SET
the MAX894L and 1050mA for the MAX895L.
S h o rt -Circ u it P ro t e c t io n
The MAX894L/MAX895L a re s hort-c irc uit-p rote c te d
switches. In the event of an output short circuit or cur-
rent-overload condition, the current through either switch
is limited by the internal current-limiting error amplifier to
Under normal operating conditions, the package can
dissipate and channel heat away. Calculate the maxi-
mum power as follows:
1.5 x I
. When the fault condition is removed, the
LIMIT
replica error amplifier sets the current limit back to I
.
2
2
LIMIT
P = I
x R
+ I
x R
LIMITB ONB
LIMITA
ONA
For a high ∆V /∆t during an output short-circuit condi-
DS
whe re R
switches A and B, respectively.
a nd R
a re the on-re s is ta nc e s of
ONB
ONA
tion, the switch turns off and disconnects the input supply
from the output. The current-limiting amplifier then slowly
turns the switch on with the output current limited to
When one or both outputs are short circuited, the volt-
age drop across the switch equals the input supply.
Hence, the power dissipated across the switch increas-
es, 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
to further dissipate heat.
1.5 x I . When the fault condition is removed, the current
SET
limit is set back to I . Refer to Output Short-Circuit
LIMIT
Fast-Loop Response and Output Short-Circuit Slow-Loop
Response in the Typical Operating Characteristics.
Th e rm a l S h u t d o w n
The MAX894L/MAX895L feature thermal shutdown. The
switch turns off when the junction temperature exceeds
+135°C. Once the device cools by 10°C, the switch turns
b a c k on. If the fa ult s hort-c irc uit c ond ition is not
removed, the switch cycles on and off, resulting in a
pulsed output.
_______________________________________________________________________________________
7
Du a l, Cu rre n t -Lim it e d , Hig h -S id e P -Ch a n n e l
S w it c h e s w it h Th e rm a l S h u t d o w n
___________________Ch ip In fo rm a t io n
TRANSISTOR COUNT: 453
SUBSTRATE CONNECTED TO GND.
4/MAX895L
__________________________________________________Ta p e -a n d -Re e l In fo rm a t io n
4.0 ±0.1
1.0 ±0.1
1.75 ±0.1
2.0 ±0.05
1.5 +0.1/-0.0 DIAMETER
A
3.5 ±0.05
8.0 ±0.3
2.2 ±0.1
0.5 RADIUS
TYPICAL
A0
1.0 MINIMUM
4.0 ±0.1
A
Bo
Ao = 3.1mm ±0.1
Bo = 2.7mm ±0.1
Ko = 1.2mm ±0.1
NOTE: DIMENSIONS ARE IN MM.
AND FOLLOW EIA481-1 STANDARD.
Ko
0.30 ±0.05
0.8 ±0.05
0.30R MAX.
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
___________________Ma x im In t e g ra t e d P ro d u c t s , 1 2 0 S a n Ga b rie l Drive , S u n n yva le , CA 9 4 0 8 6 (4 0 8 ) 7 3 7 -7 6 0 0
© 1996 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
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