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© Semiconductor Components Industries, LLC, 2012
June, 2012 − Rev. 1
1 Publication Order Number:
EVBUM2126/D
NCP1030GEVB
Isolated 2 W Bias Supply for
Telecom Systems Using the
NCP1030 Evaluation Board
User's Manual
Introduction
Power converters using secondary side controllers
provide better transient response, higher efficiency and
usually require less components than their primary side
referenced counterparts. However, secondary side
controllers require a primary side referenced bias supply to
start operation. After start−up, the controller power can be
provided from the secondary side.
The NCP1030 incorporates in a single IC all the active
power, control logic and protection circuitry required for
implementing, with a minimum of external components, a
highly integrated isolated bias supply. The features included
in the NCP1030 can result in a footprint area reduction by up
to 91% compared to a solution implemented using discrete
components.
The NCP1030 Power Switch Circuit is rated at 200 V,
making it ideal for 48 V Telecom and 42 V automotive
applications. In addition, this IC can operate from an
existing 12 V supply. The NCP1030 includes an extensive
set of features including:
• On Board Power Switch: Eliminates the need for an
external switch. As the Power Switch characteristics
are well known the gate drive is tailored to control
switching transitions and help reduce electromagnetic
interference (EMI).
• An Internal Start−up Regulator: Provides power to
the NCP1030 during start−up. After start−up, the
regulator is disabled, thus reducing power consumption.
The regulator can be powered directly from the input
line.
• Internal Error Amplifier: Allows the implementation
of an isolated supply using primary side regulation
without the need for an optocoupler.
• Internal Cycle by Cycle Current Limit: Eliminates
the need for external sensing components. The
programmed current limit is 500 mA.
• Proprietary Active Leading Edge Blanking (LEB)
Circuit: Provides better current limit control compared
to a fixed blanking period. The active LEB circuit
masks the current signal during the Power Switch turn
ON transition.
• Individual Line Undervoltage and Overvoltage
(UV/OV) Detectors with Hysteresis: Eliminate the
need for external supervisory function. The UV/OV
detectors can be disabled if not needed.
• Single Capacitor Oscillator: Eliminates traditional
timing resistor. Oscillator is optimized for operation up
to 1.0 MHz.
• Internal $2% Voltage Reference: Eliminates the
need for an external bypass capacitor.
• Thermal Shutdown Circuit: Protects the device in the
event the maximum junction temperature is exceeded.
Design Specifications
An isolated bias supply for a telecom system is designed
and implemented using the NCP1030. The supply delivers
2.0 W at 12 V. The converter specifications are listed in
Table 1.
Table 1. BIAS SUPPLY SPECIFICATIONS
Parameter Symbol Min Max
Input Voltage V
in
35 V 76 V
Frequency
İ
250 kHz 300 kHz
Peak Efficiency
h
80% −
Output Voltage V
out
10.8 V 13.2 V
Output Current I
out
0.017 A 0.17 A
Output Power P
out
2.0 W −
A Flyback topology operating in discontinuous mode is
selected because of its simplicity and low part count.
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EVAL BOARD USER’S MANUAL
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