MAX890LESA-T Maxim Integrated Products, MAX890LESA-T Datasheet - Page 6

• Manufacturer Part Number: MAX890LESA-T
• Description: Current Limit SW 1-IN 1-OUT 2.7V to 5.5V 1.2A 8-Pin SOIC N T/R
• Manufacturer: Maxim Integrated Products

Specifications of MAX890LESA-T

• Package: 8SOIC N
• Input Voltage: 2.7 to 5.5 V
• Maximum Output Current: 1.2(Typ) A
• Number Of Outputs: 1
• Operating Temperature: -40 to 85 °C

1.2A, Current-Limited, High-Side
P-Channel Switch with Thermal Shutdown
The MAX890L P-channel MOSFET power switch limits
output current to a programmed level. When the output
current is increased beyond the programmed current
limit, or 1.2A (I
the replica switch (I
(Figure 1). The current-limit error amplifier compares
the voltage across R
ence, and regulates the current back to the lesser of
the programmed limit (I
This switch is not bidirectional; therefore, the input volt-
age must be higher than the output voltage.
The MAX890L features internal current-limiting circuitry
with a maximum programmable value (I
For best performance, set the current limit (I
between 0.2 I
remains in effect throughout the input supply-voltage
range.
Program the current limit with a resistor (R
SET to ground (Figure 2) as follows:
where I
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
internal current-limiting error amplifier to 1.5 x I
When the fault condition is removed, the replica error
amplifier will set the current limit back to I
6
PIN
1, 2
6, 7
_______________________________________________________________________________________
3
4
5
8
LIMIT
R
FAULT
NAME
SET
GND
OUT
SET
ON
IN
is the desired current limit.
MAX
MAX
= 1.24V / I
I
), the current also increases through
SET
≤ I
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
Set Current-Limit Input. A resistor from SET to ground sets the current limit for the switch.
R
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.
SET
SET
Detailed Description
OUT
LIMIT
= I
LIMIT
Setting the Current Limit
Short-Circuit Protection
8
= 1.38 x 10
LIMIT
to the internal +1.24V refer-
= 1.38 x 10
/1110) and through R
) or 1.2A.
≤ I
/ 1110
MAX
3
. This current limit
/ I
3
LIMIT,
/ I
LIMIT
LIMIT
MAX
where I
) of 1.2A.
SET
.
) from
LIMIT
LIMIT
LIMIT
SET
is the desired current limit in amperes.
)
.
For a high dV
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
1.5 x I
current limit is set back to I
Circuit Fast-Loop Response and Output Over-Load
Figure 1. Functional Diagram
FAULT
FUNCTION
ON
IN
LIMIT
N
. When the fault condition is removed, the
DS
/dt during an output short-circuit condi-
CIRCUITRY
CONTROL
P
P
REPLICA
AMPLIFIER
LIMIT
HOT
Pin Description
ON
. Refer to Output Short-
CURRENT-LIMIT
AMPLIFIER
ON
MAX890L
1.24V
P
SET
GND
OUT
R
SET