NCP1203. 1203P60 Datasheet
Controller for Universal
Off−Line Supplies Featuring
Standby and Short Circuit
Housed in SOIC−8 or PDIP−8 package, the NCP1203 represents a
major leap toward ultra−compact Switchmode Power Supplies and
represents an excellent candidate to replace the UC384X devices. Due
to its proprietary SMARTMOSt Very High Voltage Technology, the
circuit allows the implementation of complete off−line AC−DC
adapters, battery charger and a high−power SMPS with few external
With an internal structure operating at a fixed 40 kHz, 60 kHz or
100 kHz switching frequency, the controller features a high−voltage
startup FET which ensures a clean and loss−less startup sequence. Its
current−mode control naturally provides good audio−susceptibility
and inherent pulse−by−pulse control.
When the current setpoint falls below a given value, e.g. the output
power demand diminishes, the IC automatically enters the so−called
skip cycle mode and provides improved efficiency at light loads
while offering excellent performance in standby conditions. Because
this occurs at a user adjustable low peak current, no acoustic noise
The NCP1203 also includes an efficient protective circuitry which,
in presence of an output over load condition, disables the output
pulses while the device enters a safe burst mode, trying to restart.
Once the default has gone, the device auto−recovers. Finally, a
temperature shutdown with hysteresis helps building safe and robust
www.Dat•aSPhebe−t4FUre.ceoPmackages are Available
• High−Voltage Startup Current Source
• Auto−Recovery Internal Output Short−Circuit Protection
• Extremely Low No−Load Standby Power
• Current−Mode with Adjustable Skip−Cycle Capability
• Internal Leading Edge Blanking
• 250 mA Peak Current Capability
• Internally Fixed Frequency at 40 kHz, 60 kHz and 100 kHz
• Direct Optocoupler Connection
• Undervoltage Lockout at 7.8 V Typical
• SPICE Models Available for TRANsient and AC Analysis
• Pin to Pin Compatible with NCP1200
• AC−DC Adapters for Notebooks, etc.
• Offline Battery Chargers
• Auxiliary Power Supplies (USB, Appliances, TVs, etc.)
D1, D2 SUFFIX
xx = Specific Device Code
A = Assembly Location
WL, L = Wafer Lot
Y, YY = Year
W, WW = Work Week
See detailed ordering and shipping information in the package
dimensions section on page 12 of this data sheet.
© Semiconductor Components Industries, LLC, 2004
October, 2004− Rev. 4
Publication Order Number:
3 CS VCC 6
*Please refer to the application information section
Figure 1. Typical Application Example
PIN FUNCTION DESCRIPTION
Pin No. Pin Name
Adjust the skipping peak current
2 FB Sets the peak current setpoint
Current sense input
The IC ground
Supplies the IC
Ensure a clean and lossless
This pin lets you adjust the level at which the cycle skipping process takes
place. Shorting this pin to ground, permanently disables the skip cycle
By connecting an optocoupler to this pin, the peak current setpoint is
adjusted accordingly to the output power demand. Skip cycle occurs when
FB falls below Vpin1.
This pin senses the primary current and routes it to the internal comparator
via an L.E.B.
The driver’s output to an external MOSFET.
This pin is connected to an external bulk capacitor of typically 22 mF.
This unconnected pin ensures adequate creepage distance.
Connected to the high−voltage rail, this pin injects a constant current into
the VCC capacitor during the startup sequence.