How to achieve low standby power consumption? PN8275 built-in 850V high pressure start and discharge module, 265VAC easy to achieve 50MW standby power consumption!
How to improve conversion efficiency? PN8308H built-in 80V / 10MΩ intelligent power MOSFET, 115VAC / 230VAC average efficiency is greater than 92%!
How to simplify the EMC design? PN8275 built-in X capacitor discharge module can be simplified by increasing X capacitance; PN8308H uses a unique current tracking technology to reduce the SR switch spike voltage, improve radiation 3DB or more!
In this issue, the Chipown Technical Team introduces you to the 12V3A six-level energy efficiency scheme based on PN8275 + PN8308H, and share the application design points.
Package and foot configuration map
PN8275 is a switching power supply chip that integrates high-pressure start-up current mode, combined with multi-mode hybrid modulation techniques and X capacitance discharge functions to achieve six-level energy efficiency, and comply with IEC 62368-1: 2014 standard requirements (CB certificate number: DK-76617) -U; PN8275 provides comprehensive protection features including input market electrical undervoltage protection, main electricity overvoltage protection, output overvoltage protection, OTP, OCP, secondary tube short circuit protection, etc.
PN8308H includes a DCM / CCM mode synchronous rectifier controller and 80V / 10MΩ intelligent power MOSFET for replacing the secondary rectifier in the flyback system of 9-20V. The periphery of PN8308H is streamlined. It uses a unique current tracking technology to quickly shut down in 50 ns, improve system EMI characteristics, and completely avoid direct damage and reduce the SR switch spike voltage.
PN8275
PN8308H
Demo physical map
Plan typical application diagram
Program characteristics
PCBA Size: 39.0mm * 86.0mm
Input voltage: 90 ~ 265VAC full voltage
Output power: 36W (Typical)
Average efficiency: ≥ 88.3% (meets COC V5 Tier2 six energy efficiency requirements)
Standby power consumption: <50MW (VIN = 265VAC)
Enter undervoltage protection, input overvoltage protection, output overvoltage protection, output overcurrent protection, etc.
Test Data
Energy efficiency test
Test conditions: VIN = 90 ~ 265VAC;
2. Adjustment rate test
3. Wenheng test
Test conditions: ambient temperature 45 ° C; housing sealed, no wind environment test; Vin = 90 ~ 265VAC, IO = 3.0a.
(Temperature data: CH1 EC1 capacitor; CH2 PN8275; CH3 10N65; CH4 primary enameled wire; CH5 magnetic core; CH6 three-layer insulation line; CH7 PN8308H)
4.x Capacitance discharge test
(Discharge time is about 0.1s @ 253VAC)
5. Municipal electric protection waveform
Test conditions: IO = 3.0A
(City Electric undervoltage protection 72VAC)
(City electricity overvoltage protection 325VAC)
EMC test
EMI conduction, radiation meets EN55022 Class B standard requirements, large margin is greater than 6dB
ESD meets IEC61000-4-2, 8kV / 15kV level requirements
EFT meets IEC 61000-4-4: 2004, 4kV rating requirements
SURGE meets IEC 61000-4-5: 2005, 4kV rating requirements
Communication insulation meets 3.75kV requirements
Application point
1 synchronous rectification
The PN8308H is turned on and turned off and turned off and turned off and turned off and turned off the SR, internal curing TONMIN and TOFFMIN in accordance with the internal MOSFET of the VDS voltage and ISD current. It supported 150 kHz switching frequency.
SW and GND pin recommendation to increase RC absorption to reduce VDS spikes in CCM mode, VDD pin recommends adding RC low-pass filtering to enhance the ESD capabilities of the system.
2 input capacitance CBUS selection
The CBUS capacity determines the volatility of the converter input voltage Vg, which is known from energy conservation.
In CCM mode, Vg, Min and maximum duty cycle DMAX relationships are as follows
Since the PN8275 built-in slope compensation is compensated and allows DMAX>0.7, the large turns ratio and small input capacitor design are supported compared to the PSR product (usually DMAX is within 0.5).
3 transformer design
Step 1: The transformers N and LP are set under high voltage input (VG2 = 300V, FS = 65kHz) & rated load, so that it is in critical transformers in critical mode, opening near the first grain, and in the IDLIMIT operating point transformer Unsaturated.
Step 2: At low voltage input (VG1 = 90V, FS = 65kHz) & rated load, calculation KRP and DMAX, set the number of wires and turns of the transformer in the secondary side winding, and the current density is reasonable and can be wound.
Step 3: Set the VCC & Shield Winding, select the winding structure: between the power supply 8-40V, the Y capacitor is interfering 2V.
4DMG parameter setting
Set R2 according to the output OVP voltage
R3, R1 sets OCP line voltage compensation amount, read full text, original title: 12V3A, built-in X capacitor discharge and high pressure synchronous rectification six-level energy efficiency scheme
Article Source: [Micro Signal: Chipown, WeChat public number: 朋 微 电子] Welcome to add attention! Please indicate the source of the article.
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