APL5930 Anpec Electronics Corporation, APL5930 Datasheet - Page 10

• Manufacturer Part Number: APL5930
• Description: 3a, Ultra Low Dropout 0.23v Typical Linear Regulator
• Manufacturer: Anpec Electronics Corporation

APL5930
Function Description
Power-On-Reset
A Power-On-Reset (POR) circuit monitors both of supply
voltages on VCNTL and VIN pins to prevent wrong logic
controls. The POR function initiates a soft-start process
after both of the supply voltages exceed their rising POR
voltage thresholds during powering on. The POR func-
tion also pulls low the POK voltage regardless the output
status when one of the supply voltages falls below its
falling POR voltage threshold.
Internal Soft-Start
An internal soft-start function controls rise rate of the out-
put voltage to limit the current surge during start-up. The
typical soft-start interval is about 0.6 ms.
Output Voltage Regulation
An error amplifier works with a temperature-com-
pensated 0.8V reference and an output NMOS regulates
output to the preset voltage. The error amplifier is de-
signed with high bandwidth and DC gain provides very
fast transient response and less load regulation. It com-
pares the reference with the feedback voltage and ampli-
fies the difference to drive the output NMOS which pro-
vides load current from VIN to VOUT.
Current-Limit Protection
The APL5930 monitors the current flowing through the
output NMOS and limits the maximum current to prevent
load and APL5930 from damages during current over-
load conditions.
Short Current-Limit Protection
The short current-limit function reduces the current-limit
level down to 1.1A (typical) when the voltage on FB pin
falls below 0.2V (typical) during current overload or short-
circuit conditions.
The short current-limit function is disabled for success-
ful start-up during soft-start interval.
Copyright
Rev. A.1 - Jun., 2008
ANPEC Electronics Corp.
10
Thermal Shutdown
A thermal shutdown circuit limits the junction tempera-
ture of APL5930. When the junction temperature exceeds
+170
lowing the device to cool down. The regulator regulates
the output again through initiation of a new soft-start pro-
cess after the junction temperature cools by 50
ing in a pulsed output during continuous thermal over-
load conditions. The thermal shutdown is designed with
a 50
ture during continuous thermal overload conditions, ex-
tending lifetime of the device.
For normal operation, the device power dissipation should
be externally limited so that junction temperatures will
not exceed +125
Enable Control
The APL5930 has a dedicated enable pin (EN). A logic
low signal applied to this pin shuts down the output. Fol-
lowing a shutdown, a logic high signal re-enables the
output through initiation of a new soft-start cycle. When
left open, this pin is pulled up by an internal current source
(5 A typical) to enable normal operation. It’ s not neces-
sary to use an external transistor to save cost.
Power-OK and Delay
The APL5930 indicates the status of the output voltage by
monitoring the feedback voltage (V
V
old (V
the end of the delay time, the IC turns off the internal
NMOS of the POK to indicate that the output is ok. As the
V
threshold, the IC turns on the NMOS of the POK (after a
debounce time of 10 s typical).
FB
FB
rises and reaches the rising Power-OK voltage thresh-
falls and reaches the falling Power-OK voltage
o
o
C hysteresis to lower the average junction tempera-
C, a thermal sensor turns off the output NMOS, al-
THPOK
), an internal delay function starts to work. At
o
C.
FB
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) on FB pin. As the
o
C, result-