RDK-257 Power Integrations, RDK-257 Datasheet - Page 4

• Manufacturer Part Number: RDK-257
• Description: REFERENCE DESIGN LINKSWITCH-PH
• Manufacturer: Power Integrations
• Series: LinkSwitch®-PHr

Specifications of RDK-257

• Design Resources: RDR-257
• Current - Output / Channel: 330mA
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 36V
• Voltage - Input: 90 ~ 265VAC
• Utilized Ic / Part: LNK405EG
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 596-1424

Figure 5.
5.9 V Regulator/Shunt Voltage Clamp
The internal 5.9 V regulator charges the bypass capacitor
connected to the BYPASS pin to 5.9 V by drawing a current
from the voltage on the DRAIN pin whenever the power
MOSFET is off. The BYPASS pin is the internal supply voltage
node. When the power MOSFET is on, the device operates
from the energy stored in the bypass capacitor. Extremely low
power consumption of the internal circuitry allows LinkSwitch-PH
to operate continuously from current it takes from the DRAIN
pin. A bypass capacitor value of 10 or 100 mF is sufficient for
both high frequency decoupling and energy storage. In
addition, there is a 6.4 V shunt regulator clamping the BYPASS
pin at 6.4 V when current is provided to the BYPASS pin
through an external resistor. This facilitates powering of
LinkSwitch-PH externally through a bias winding to increase
operating efficiency. It is recommended that the BYPASS pin is
supplied current from the bias winding for normal operation.
Auto-Restart
In the event of an open-loop fault (open FEEDBACK pin resistor
or broken path to feedback winding), output short-circuits or an
overload condition the controller enters into the auto-restart
mode. The controller annunciates both short-circuit and
open-loop conditions once the FEEDBACK pin current falls
below the I
minimize the power dissipation under this fault condition the
shutdown/auto-restart circuit turns the power supply on (same
as the soft-start period) and off at an auto-restart duty cycle of
typically DC
fault is removed during the auto-restart off-time, the power
supply will remain in auto-restart until the full off-time count is
completed. Special consideration must be made to appropriately
size the output capacitor to ensure that after the soft-start
period (t
threshold to ensure successful power-supply start-up.
After the soft-start time period, auto-restart is activated only
when the FEEDBACK pin current falls below I
Rev. C 11/10
LNK403-409EG/413-419EG
4
SOFT
Remote ON/OFF VOLTAGE MONITOR pin Control
FB(AR)
) the FEEDBACK pin current is above the I
AR
for as long as the fault condition persists. If the
threshold after the soft-start period. To
D
S
CONTROL
R
V
FB
BP
PI-5435-052510
FB(AR)
.
FB(AR)
Over-Current Protection
The current limit circuit senses the current in the power MOSFET.
When this current exceeds the internal threshold (I
MOSFET is turned off for the remainder of that cycle. A leading
edge blanking circuit inhibits the current limit comparator for a
short time (t
leading edge blanking time has been set so that current spikes
caused by capacitance and rectifier reverse recovery will not
cause premature termination of the power MOSFET conduction.
Line Under/Overvoltage Protection
This device includes both line under- and overvoltage detection
to limit the minimum start-up and maximum operating voltage
detected through the VOLTAGE MONITOR pin. An external peak
detector consisting of a diode and capacitor are required to
provide input line peak voltage to the VOLTAGE MONITOR pin
through a resistor. At power up, I
off until the input line voltage reaches the undervoltage threshold.
At power down, I
goes out of regulation.
The same resistor used for UV also sets line overvoltage (OV)
shutdown threshold which, once exceeded, forces the
LinkSwitch-PH to stop switching (after completion of the current
switching cycle). Once the line voltage returns to normal, the
device resumes normal operation. A small amount of hysteresis
is provided on the OV threshold to prevent noise triggering.
When the power MOSFET is off, the rectified DC high voltage
surge capability is increased to the voltage rating of the power
MOSFET (725 V), due to the absence of the reflected voltage
and leakage spikes on the drain.
Hysteretic Thermal Shutdown
The thermal shutdown circuitry senses the controller die
temperature. The threshold is set at 142 °C typical with a 75 °C
hysteresis. When the die temperature rises above this threshold
(142 °C) the power MOSFET is disabled and remains disabled
until the die temperature falls by 75 °C, at which point the power
MOSFET is re-enabled.
Safe Operating Area (SOA) Protection
The device also features a safe operating area (SOA) protection
mode which disables MOSFET switching for 40 cycles in the
event the peak switch current reaches the ILIMIT threshold and
the switch on-time is less than t
protects the device under short-circuited LED conditions and at
start-up during the soft-start period when auto-restart protection
is inhibited. The SOA protection mode remains active in normal
operation.
LEB
) after the power MOSFET is turned on. This
UV-
prevents restart attempts after the output
ON(SOA)
UV+
keeps the LinkSwitch-PH
. This protection mode
www.powerint.com
LIMIT
), the power