MAX890LC/D Maxim, MAX890LC/D Datasheet - Page 6

• Manufacturer Part Number: MAX890LC/D
• Description: 1A / Current-Limited / High-Side P-Channel Switch with Thermal Shutdown
• Manufacturer: Maxim

1A, 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 1A (I
the replica switch (I
(Figure 1). The current-limit error amplifier compares
the voltage across R
and regulates the current back to the lesser of the pro-
grammed 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
best performance, set the current limit (I
0.2 I
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
For a high dV
tion, the switch turns off and disconnects the input supply
6
PIN
1, 2
6, 7
_______________________________________________________________________________________
3
4
5
8
MAX
LIMIT
R
≤ I
FAULT
NAME
SET
GND
OUT
SET
ON
LIMIT
IN
is the desired current limit.
MAX
DS
= 1.24V / I
LIMIT
/dt during an output short-circuit condi-
), the current also increases through
I
≤ I
SET
Input. P-channel MOSFET source. Bypass IN with a 1 F 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 0.1 F 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
) or 1A.
MAX
SET
Detailed Description
OUT
= I
Setting the Current Limit
to the internal 1.24V reference,
Short-Circuit Protection
8
= 1.38 x 10
. This current limit remains in
LIMIT
= 1.38 x 10
/1110) and through R
/ 1110
3
/ I
3
LIMIT,
/ I
MAX
LIMIT
LIMIT
LIMIT
where I
) of 1A. For
) between
SET
.
) from
LIMIT
LIMIT
SET
is the desired current limit in amperes.
.
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 Short-Circuit
Slow-Loop Response in the Typical Operating
Characteristics .
Figure 1. Functional Diagram
FAULT
FUNCTION
ON
IN
LIMIT
N
. When the fault condition is removed, the
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