MAX869L Maxim, MAX869L Datasheet - Page 7

• Manufacturer Part Number: MAX869L
• Description: The MAX869L P-channel load switch features an accurate user-set current limit and low on-resistance
• Manufacturer: Maxim

Figure 1. Functional Diagram
The MAX869L is a short-circuit-protected switch. In the
event of an output short circuit (V
the current through the switch is limited by the internal
current-limiting error amplifier to 1.4 x I
short-circuit condition is removed, the current-limit
amplifier sets the current limit back to I
For a high ∆V
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
1.4 x I
removed, the current limit is set back to I
Fast Current-Limit Response and Slow Current-Limit
Response graphs in the Typical Operating Characteristics .
The MAX869L 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 condition is not removed, the switch
cycles on and off, resulting in a pulsed output.
FAULT
ON
IN
LIMIT
N
. When the short-circuit condition is
P-Channel Switch with Thermal Shutdown
DS
/∆t during an output short-circuit condi-
_______________________________________________________________________________________
CIRCUITRY
CONTROL
Short-Circuit Protection
P
P
REPLICA
AMPLIFIER
HOT
ON
Thermal Shutdown
OUT
CURRENT-LIMIT
AMPLIFIER
ON
MAX869L
LIMIT
LIMIT
LIMIT
≤ 1.6V typical),
1.24V
2A, Current-Limited, High-Side
.
. Refer to the
P
. When the
SET
GND
OUT
R
SET
The MAX869L 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.
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.
Connect a 0.1µF capacitor from OUT to GND to prevent
inductive parasitics from pulling OUT below GND dur-
ing turn-off. USB applications require C
least 120µF. This larger output capacitance slows the
output rise and fall times, as shown in the Typical
Operating Characteristics , but does not adversely
affect the MAX869L’s turn-off response time.
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 to reduce the effect
of undesirable parasitic inductance. Place input and
output capacitors as close as possible to the device
(less than 5mm).
Figure 2. Setting the Current Limit
__________Applications Information
Layout and Thermal-Dissipation
MAX869L
GND
SET
Output Capacitor
Input Capacitor
Considerations
Fault Indicator
OUT
R
SET
to be at
7