NCP1351LEDGEVB ON Semiconductor, NCP1351LEDGEVB Datasheet - Page 11

• Manufacturer Part Number: NCP1351LEDGEVB
• Description: EVAL BOARD FOR NCP1351LEDG
• Manufacturer: ON Semiconductor

Specifications of NCP1351LEDGEVB

• Design Resources: NCP1351 EVB BOM NCP1351LEDGEVB Gerber Files NCP1351LED EVB Schematic
• Current - Output / Channel: 700mA
• Outputs And Type: 1, Isolated
• Voltage - Output: 33V
• Features: Short-Circuit Protection
• Voltage - Input: 85 ~ 265 V
• Utilized Ic / Part: NCP1351
• Core Chip: NCP1351
• Topology: Flyback
• No. Of Outputs: 1
• Output Current: 700mA
• Output Voltage: 33V
• Development Tool Type: Hardware - Eval/Demo Board
• Leaded Process Compatible: Yes
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: NCP1351LEDG
• Other names: NCP1351LEDGEVBOS

The constant current constant voltage secondary control loop is very flexible and is implemented using a PNP (Q3) with a
pair of current sense resistors (R12 & R13) to regulate the current and provide control of the optocoupler to the NCP1351.
In addition, there is a maximum voltage control loop that is implemented using zener D10. To modify this circuit for
alternate current / voltage configurations, these components should be modified. The table on the front page shows
several other possible configuration options.
transformer design and FET used, as the current decreases, the maximum voltage capability increases. For example, for
20W output, the maximum voltage at 350 mA could be as high as 57 Vdc. Under UL1310, Class 2 power supplies for use
in dry/damp environments are allowed to have a maximum output voltage of 60 Vdc.
implemented using a BC857 transistor which has a maximum V
this transistor can be changed to a BC856 (maximum V
performance for a nominal 350 mA output current with the component changes as noted.
September 2008, Rev. 2
Disclaimer: ON Semiconductor is providing this design note “AS IS” and does not assume any liability arising from its use; nor
does ON Semiconductor convey any license to its or any third party’s intellectual property rights. This document is provided only to
assist customers in evaluation of the referenced circuit implementation and the recipient assumes all liability and risk associated
with its use, including, but not limited to, compliance with all regulatory standards. ON Semiconductor may change any of its
products at any time, without notice.
Design note created by Anthony Middleton, e-mail: [e-mail]
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
0
R12 & R13 = 3.6 ohms each, D10 = MMSZ5263B (56V), Q3 = BC856
5
Typical Current Regulation versus Load, T
Modifying the Board for Other LED currents
10
15
1
© 2008 ON Semiconductor.
LED Forward Voltage (Vdc)
20
Note because this design is ultimately power limited based on the
DN06040/D
www.onsemi.com
25
CEO
of -65 Vdc). The figure below shows the current regulation
30
CEO
of -45 Vdc. If a higher operating voltage is required,
35
a
= 21˚C / 70˚F
40
45
On the demo board, Q3 is
50
55
60
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