ON Semiconductor NCP1219PRINTGEVB, Руководство пользователя

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©
Semiconductor Components Industries, LLC, 2012
November, 2012 − Rev. 3
1 Publication Order Number:
EVBUM2161/D
NCP1219PRINTGEVB
NCP1219 48 W Printer
Evaluation Board User's
Manual
Introduction
The NCP1219 is the newest part in the NCP12XX family
of current − mode flyback controllers. The controller features
dynamic self supply (DSS), eliminating the need for
external startup circuitry, contributing to a cost effective,
low parts count flyback controller design. The NCP1219
also includes a user programmable skip cycle threshold,
reducing power dissipation at light loads and in standby
mode. An externally provided latch signal delivered to the
Skip/latch pin allows the realization of protection
functionality.
The 48 W ac adapter evaluation board targets a printer
adapter application with a 24 V output, reconfigurable to
7.25 V in standby mode selectable with an external signal.
The use of DSS mode is demonstrated for low input
voltages, while an auxiliary winding is used for higher input
voltages to maintain standby power below 1 W. The
NCP1219 evaluation board shows latched
− mode protection
function through the optional primary and secondary
overvoltage protection circuits.
The evaluation board is designed as an off − line printer
adapter power supply. The adapter operates across universal
inputs, 85 Vac to 265 Vac (47 Hz – 63 Hz). The adapter
supplies a regulated 24 V output. It can deliver a steady state
30 W output with transient capability of 48 W, as defined in
Figure 1.
Figure 1. Transient Output Current Specification
time (ms)
Output Current (A)
0.92 A
2.0 A
1.25 A
700 ms
300 ms
The system has a low voltage standby mode enabled by
pulling the MC node low. In standby mode the converter
supplies 70 mA of standby current at 7.25 V while
maintaining input power below 1 W. The system is
self
− contained, with the NCP1219 bias being provided by
the bulk voltage through an internal startup circuit. The IC
bias is provided by either DSS for low input voltages, or an
auxiliary winding for higher input voltages. The
specifications are summarized in Table 1.
Table 1. SUMMARY OF EVALUATION BOARD
SPECIFICATIONS
Requirement Unit Min Max
Input Voltage Vac 85 265
Line Frequency Hz 47 63
Output Voltage Vdc 23.8 24.2
Output Current Adc − 1.25 (2.0 transient
peak)
Output Power W − 30 (48 transient peak)
Average
Efficiency (EPA
Energy Star 2.0
Compliance)
h
avg
83.5 −
Standby Voltage Vdc 7 8
Standby Power W − 1
Output Ripple
Voltage
mV − 200
Output Voltage
Under/Overshoot
During Transient
Load Step from
0.92 A to 2.0 A
mV − 200
Design Procedure
The converter design procedure is divided into several
steps:
•
Power Component Selection
•
Loop Stability Analysis and Compensation
•
IC Supply Circuits
•
External Protection Circuits
•
Standby Reconfiguration Circuit
Throughout this application note, the minimum and
maximum input voltages are referred as low and high line,
respectively.
The evaluation board schematic is provided in Figure 2
for reference to component values throughout the design
procedure.
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EVAL BOARD USER’S MANUAL