DPA423 Power Integrations, Inc., DPA423 Datasheet - Page 3

• Manufacturer Part Number: DPA423
• Description: Highly Integrated DC-DC Converter Ics For Distributed Power Architecturesthe Dpa-switch ic Family Introduces a Highly Integratedsolution For DC-DC Conversion Applications in The 16-75 Vdcinput Range.dpa-switch Uses The Same Proven Topology as Topswit
• Manufacturer: Power Integrations, Inc.

Figure 2. Functional Block Diagram.
Pin Functional Description
DRAIN (D) Pin:
High voltage power MOSFET drain output. The internal startup
bias current is drawn from this pin through a switched high-
voltage current source. Internal current limit sense point for
drain current.
CONTROL (C) Pin:
Error amplifier and feedback current input pin for duty cycle
control. Internal shunt regulator connection to provide internal
bias current during normal operation. It is also used as the
connection point for the supply bypass and auto-restart/
compensation capacitor.
LINE-SENSE (L) Pin:
Input pin for overvoltage (OV), under-voltage (UV) lock out,
line feed forward with the maximum duty cycle (DC
reduction, remote ON/OFF and synchronization. A connection
to SOURCE pin disables all functions on this pin.
EXTERNAL CURRENT LIMIT (X) Pin:
Input pin for external current limit adjustment and remote
ON/OFF. A connection to SOURCE pin disables all functions
on this pin.
CURRENT LIMIT (X)
FREQUENCY (F)
LINE-SENSE (L)
EXTERNAL
CONTROL (C)
R E
Z C
I FB
SHUNT REGULATOR/
ERROR AMPLIFIER
CURRENT
ADJUST
LIMIT
SENSE
V BG + V T
LINE
+
V BG
-
V C
1 V
V I (LIMIT)
ON/OFF
5.8 V
OV/UV
DC MAX
START
SOFT
STOP LOGIC
OSCILLATOR
5.8 V
4.8 V
COMPARATOR
INTERNAL UV
DC MAX
300/400 kHz
STOP SOFT-
+
-
START
CLOCK
D MAX
SAW
MAX
SKIPPING
CYCLE
)
SOFT START
FREQUENCY (F) Pin:
Input pin for selecting switching frequency: 400 kHz if connected
to SOURCE pin and 300 kHz if connected to CONTROL pin.
SOURCE (S) Pin:
Output MOSFET source connection for the power return.
Primary side control circuit common and reference point.
Figure 3. Pin Configuration (top view).
COMPARATOR
AUTO-RESTART
SHUTDOWN/
HYSTERETIC
PWM
SHUTDOWN
THERMAL
-
+
÷ 8
C
X
L
F
G Package (SMD-8)
P Package (DIP-8)
SOURCE Pin (See layout considerations)
0
1
2
3
4
1
INTERNAL
SUPPLY
Tab Internally Connected to
R
S
Q
8
5
7
6
S
S
S
D
CONTROLLED
GATE DRIVER
CURRENT LIMIT
COMPARATOR
TURN-ON
BLANKING
+
-
LEADING
DPA423-426
EDGE
(TO-263-7C)
R Package
C L X S F
1 2 3 4 5
PI-2760-070501
PI-2760-070501
PI-3822-041304
4/04
DRAIN (D)
SOURCE (S)
D
7
L
3