APL5605 Anpec Electronics Corporation, APL5605 Datasheet - Page 9

• Manufacturer Part Number: APL5605
• Description: 600ma Linear Regulator For Dc Fan Speed Control
• Manufacturer: Anpec Electronics Corporation

Function Descriptions
Under-Voltage Lock-Out (UVLO)
The APL5605 has a built-in under-voltage lock-out circuit
to keep the output off until the internal circuitry is operat-
ing properly. The UVLO function initiates a soft start pro-
cess after input voltage exceeds its rising UVLO thresh-
old during power on. Typical UVLO threshold is 2.5V
with 0.15V hysteresis.
Soft-Start
The APL5605 provides an internal soft-start circuitry to
control rise rate of the output voltage and limit the cur-
rent surge during start-up. Approximate 20 s delay time
after the V
soft-start. The typical soft-start interval is about 130 s.
Enable/Shutdown
Driving the EN high turns on the regulator, driving the EN
low puts the regulator into shutdown mode. A logic low
also causes the output voltage to discharge to GND. The
EN is pulled low by an internal resistor.
Current Limit
The APL5605 provides a current limit circuitry, which
monitors the output current and controls P-MOS’ s gate
voltage to limit the output current at 700mA.
Foldback Current Limit
When the output voltage drops below 0.6V (typical),which
is caused by over load or short circuit, the foldback cur-
rent limit circuitry limits the output current to 250mA. The
foldback current limit is used to ruduce the power dissi-
pation during short circuit condition. The foldback current
limits is disabled for 0.8ms(typical) after UVLO threshold
is reached, so that the IC has normal 700mA (typical)
current limit level during start-up.
Copyright
Rev. A.1 - Jan., 2008
APL5605
IN
is over the UVLO threshold, the IC starts a
ANPEC Electronics Corp.
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Thermal Shutdown
A thermal shutdown circuit limits the junction temperature
of APL5605. When the junction temperature exceeds
+150 C, the thermal shutdown circuitry disables the
output, allowing the device to cool down. The output
circuitry is enabled again after the junction tempera-
ture cools down by 40 C, resulting in a pulsed output
during continuous thermal overload conditions.
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