DPA423PN Power Integrations, DPA423PN Datasheet - Page 8

• Manufacturer Part Number: DPA423PN
• Description: IC CONV DC-DC DPA SWITCH 8DIP
• Manufacturer: Power Integrations
• Series: DPA-Switch®r

Specifications of DPA423PN

• Applications: Converter, Power Over Ethernet and Telecom Applications
• Voltage - Input: 16 ~ 75 V
• Number Of Outputs: 1
• Voltage - Output: 220V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Through Hole
• Package / Case: 8-DIP (0.300", 7.62mm)
• Output Voltage: 9 V
• Output Current: 1.75 A
• Input Voltage: - 0.3 V to + 220 V
• Switching Frequency: 282 KHz to 425 KHz
• Operating Temperature Range: - 40 C to + 150 C
• Mounting Style: Through Hole
• Duty Cycle (max): 79 %
• For Use With: 596-1009 - KIT DESIGN ACCELERATOR DC-DC596-1007 - KIT DESIGN ACCELERATOR POE CONV
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 596-1011-5

(typical), the CONTROL pin goes into the hysteretic mode
of operation. In this mode, the CONTROL pin goes through
alternate charge and discharge cycles between 4.8 V and
5.8 V (see CONTROL Pin Operation section above) and the IC
runs entirely off the high voltage DC input, but with very low
power consumption (30 mW typical at 48 V with LINE-SENSE
and EXTERNAL CURRENT LIMIT pins open). When the
DPA-Switch is remotely turned on after entering this mode,
it will initiate a normal start-up sequence with soft-start the
next time the CONTROL pin reaches 5.8 V. In the worst case,
the delay from remote on to start-up can be equal to the full
discharge/charge cycle time of the CONTROL pin, which is
approximately 36 ms for a 22 µF CONTROL pin capacitor. This
reduced-consumption remote-off mode can eliminate expensive
and unreliable in-line mechanical switches. It also allows for
microprocessor-controlled turn-on and turn-off sequences that
may be required in certain applications.
Synchronization
In addition to sensing incoming current for OV, UV and
remote ON/OFF, the LINE-SENSE pin also monitors its pin
voltage through a 1 V threshold comparator. A pin voltage
below 1 V turns on DPA-Switch. When the voltage at LINE-
SENSE pin rises beyond 1 V to disable the output, DPA-Switch
completes its current switching cycle before the output is
forced off (similar to remote ON/OFF operation). The internal
oscillator is stopped at the end of the current cycle awaiting the
LINE-SENSE pin voltage to go low to start the next cycle. This
allows the use of the 1 V threshold to synchronize DPA-Switch
to an external signal with a frequency lower than its internal
switching frequency. A transistor or an optocoupler output
connected between the LINE-SENSE pin and the SOURCE
pin implements this function (see Figure 24). Please refer to
Figure 6 for the timing waveforms of synchronization
operation.
In order to be recognized as a synchronization pulse, the
LINE-SENSE pin needs to stay low (on-time) for at least
120 ns but no more than 2250 ns for 400 kHz (or 3080 ns for
300 kHz) internal switching frequency. In addition, the off-
time must be kept below 7.7 µs, which is a limitation set by
the lowest synchronization frequency of 128 kHz allowed by
the chip. The effective DC
can be calculated as 0.75
7.7 µs may force the CONTROL pin to go into the hysteretic
mode and initiate a soft-start cycle at next turn-on.
Soft-Start
Two on-chip soft-start functions are activated at start-up with
a duration of 5 ms (typical). Maximum duty cycle starts from
0% and linearly increases to the default maximum of 75% at
the end of the 5 ms duration and the current limit starts from
about 85% and linearly increases to 100% at the end of the
5 ms duration. In addition to start-up, soft-start is also activated
8
DPA423-426
P
7/05
•
f
MAX
SYNC
for synchronization operation
/f
OSC
. An off-time longer than
at each restart attempt during auto-restart and when restarting
after being in hysteretic regulation of CONTROL pin voltage
(V
effectively minimizes current and voltage stresses on the output
MOSFET, the clamp circuit and the output rectifier during
start-up. This feature also helps minimize output overshoot and
prevents saturation of the transformer during start-up.
Shutdown/Auto-Restart
To minimize DPA-Switch power dissipation under fault
conditions, the shutdown/auto-restart circuit turns the power
supply on and off at an auto-restart duty cycle of typically 4%
if an out of regulation condition persists. Loss of regulation
interrupts the external current into the CONTROL pin. V
regulation changes from shunt mode to the hysteretic auto-
restart mode as described in CONTROL pin operation section.
When the fault condition is removed, the power supply output
becomes regulated, V
normal operation of the power supply resumes.
Hysteretic Over-Temperature Protection
Over temperature protection is provided by a precision analog
circuit that turns the output MOSFET off when the junction
temperature exceeds the thermal shutdown temperature
(137 °C typical). When the junction temperature cools to below
the hysteretic temperature (110 °C typical), normal operation
resumes providing automatic recovery. V
hysteretic mode and a 4.8 V to 5.8 V (typical) sawtooth waveform
is present on the CONTROL pin while in thermal shutdown.
Bandgap Reference
All critical DPA-Switch internal voltages are derived from a
temperature-compensated bandgap reference. This reference
is also used to generate a temperature-compensated current
reference that is trimmed to accurately set the switching
frequency, current limit, and the line OV/UV thresholds.
DPA-Switch has improved circuitry to maintain all of the above
critical parameters within very tight absolute and temperature
tolerances.
High-Voltage Bias Current Source
This current source biases DPA-Switch from the DRAIN pin
and charges the CONTROL pin external capacitance during
start-up or hysteretic operation. Hysteretic operation occurs
during auto-restart, remote off and over-temperature shutdown.
In this mode of operation, the current source is switched on and
off with an effective duty cycle of approximately 20%. This
duty cycle is determined by the ratio of CONTROL pin charge
(I
is turned off during normal operation when the output MOSFET
is switching. The effect of the current source switching may be
seen on the DRAIN voltage waveform as small disturbances,
which is normal.
C(CH)
C
), due to remote off or thermal shutdown conditions. This
) and discharge currents (I
C
regulation returns to shunt mode, and
CD1
and I
CD2
). This current source
C
is regulated in
C