深圳市钲铭科电子有限公司 SM7525 Primary Side Feedback Controlling Switch v1.6 GOSTON ELECTRONICS CO.,LTD SM7525 z z z z z z z z z Applications LED lighting driver SOP8 Output Power Meter Input Voltage 85Vac～265Vac 180Vac～265Vac Output Power 1~5W 5~7W Typical Application 8 DRAIN Pin Figure GND z GND z SM7525 is a primary side feedback controlling power chip used in off-line small power AC/DC switching power. It realizes high precision (less than ±5%) constant current output under universal input voltage. The circuit is no loop compensation and saves opto-coupler, L431, transformer auxiliary winding and other components to reduce the cost. The circuit integrates cycle by cycle peak current limiting, FB overvoltage protection, output open/short protection and soft-start, which optimize the reliability. 5 z Topological structure support: Fly-back and low-cost BUCKBoost Integrated 730V hybrid technology Universal input voltage: 85Vac~265Vac Constant current precision less than ±5% Universal voltage compatible with 1~5W SunMoon patented no auxiliary winding of primary side feedback control technology without coupler, 431 and other components. No loop compensation Built-in LEB circuit Cycle by cycle peak current limiting Output open/short circuit Built-in soft-start Built-in overvoltage protection and short circuit protection Package：SOP8 7 DRAIN z General Description 6 Features AC DC 1 2 3 4 CS FB NC VCC SM7525 Absorbing Circuit Mail : [email protected] Tel: 0755 -27593075 Address: 3F,SSMEC Bldg.,15 South 1st Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen. Note: The latest datasheet is subject to the web(www.dianyuanic.com). -1- Fax: 0755 -29031113 深圳市钲铭科电子有限公司 SM7525 Primary Side Feedback Controlling Switch v1.6 GOSTON ELECTRONICS CO.,LTD Pin Schematics CS 1 8 DRAIN FB 2 7 DRAIN NC 3 6 GND VCC 4 5 GND SM7525 SOP8 Pin Description Symbol Pin Number Pin Description CS 1 Primary Side Peak Current Detection Port FB 2 Output Voltage Feedback Port NC 3 No Connection VDD 4 Internal Power Supply Voltage Port GND 5,6 Ground DRAIN 7.8 Open-drain of MOSFET Mail : [email protected] Tel: 0755 -27593075 Address: 3F,SSMEC Bldg.,15 South 1st Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen. Note: The latest datasheet is subject to the web(www.dianyuanic.com). -2- Fax: 0755 -29031113 深圳市钲铭科电子有限公司 SM7525 Primary Side Feedback Controlling Switch v1.6 GOSTON ELECTRONICS CO.,LTD Limiting Values Limiting Parameters (TA= 25℃) Symbol Description Range Unit VDD Operating Voltage -0.3~6 V VFB FB Input Voltage ~ V VCS CS Input Voltage -0.3~7.0 V TA Operating Temperature -20~125 ℃ Tstg Storage Temperature -40~150 ℃ VESD HBM 4 KV Rθja Thermal Resistance 65 ℃/W Vds Drain Source Breakdown Voltage -0.3~730 V Electrical Operating Parameters ((No special instruction，normal condition TA=25℃，VDD=6V) Symbol Description ICC Static Current Vcc Power Supply Voltage Vcs TLEB VFBMIN Range Min Type Max Unit -250 uA 6 V Current Detection Threshold 620 mV Leading Edge Blanking Time 450 ns 300 mV FB Minimum Threshold Value VFBMAX FB Overvoltage Threshold 4 V TDEM_MIN Minimum Degaussing Time 5 us DMAX Maximum Duty Cycle 42 % RDSON On-Resistance 15 Ohm 730 V 4 V BVD_SS Vcc_uvlo Drain Source Breakdown Voltage Vcc under-voltage protection threshold Mail : [email protected] Tel: 0755 -27593075 Address: 3F,SSMEC Bldg.,15 South 1st Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen. Note: The latest datasheet is subject to the web(www.dianyuanic.com). -3- Fax: 0755 -29031113 深圳市钲铭科电子有限公司 SM7525 Primary Side Feedback Controlling Switch v1.6 GOSTON ELECTRONICS CO.,LTD Functional Description SM7525 is a primary side feedback controlling power chip used in off-line small power AC/DC switching power. It realizes high precision (less than ±5%) constant current output under universal input voltage. SM7525 controls system output through primary side sampling mode. It integrates high voltage process and saves opto-coupler, TL431 and other components. Circuit contains cycle-by-cycle peak current limiting, FB overvoltage protection, output open/short circuit protection and soft-start function to optimize the system reliability. Start-up and Control SM7525 contains high-voltage power switch. Traditional circuit external startup resistor and power supply circuit of auxiliary winding can be eliminated by high-voltage startup, which reduces system cost greatly. Operating Principle SM7525 must operate under DCM to realize high precision of the primary side constant current control, and fly-back power application. The circuit controls current and voltage through reflected voltage from detecting primary side auxiliary winding. Output current is only controlled by transformer turns ratio and primary current peak value： Io = 2 / 7 × N × I P （1） Note：Io is output current ；N is transformer turns ratio； η is conversion efficiency Operating Frequency SM7525 switching frequency is controlled by the load without external setting components (Maximum switching frequency less than 65K). In discontinuous mode fly-back power supply, the maximum output power is： 1 Po = × L P × FSW × IP2 2 （3） LP is primary side auxiliary winding inductance; IP is primary side auxiliary winding peak current. Formula 3 shows the change in primary side auxiliary winding inductance leads to maximum power output and constant current change under constant current mode. In order to compensate for the changes in the primary side inductance, internal loop locks the switch frequency. The frequency is shown below： FSW = 4 7 × TDEMAG (4) Because degaussing time TDEMAG is inversely proportional to inductance and the product of LP and FSW is unchanged through frequency lock, maximum output power and constant current under constant current mode will not change with the primary side inductance. SM7525 can compensate inductance maximum ±10%. Mail : [email protected] Tel: 0755 -27593075 Address: 3F,SSMEC Bldg.,15 South 1st Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen. Note: The latest datasheet is subject to the web(www.dianyuanic.com). -4- Fax: 0755 -29031113 深圳市钲铭科电子有限公司 SM7525 Primary Side Feedback Controlling Switch v1.6 GOSTON ELECTRONICS CO.,LTD Current Detection and LEB SM7525 controls the power switch by detecting the resistor voltage of CS, so that the transformer primary current control is achieved and cycle-by cycle peak current limiting is provided. Switch current inputs CS pin by accessing to the external detection resistor. In order to eliminate the interference caused by open of high voltage power MOSFET, it is built-in leading edge blanking circuit. Therefore, there is no need for external RC filter circuit and reducing cost is achieved. Protection Control SM7525 improves the various protection functions and optimizes the power reliability including cycle-by-cycle peak current limiting, short circuit protection, FB overvoltage protection and soft-start. Mail : [email protected] Tel: 0755 -27593075 Address: 3F,SSMEC Bldg.,15 South 1st Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen. Note: The latest datasheet is subject to the web(www.dianyuanic.com). -5- Fax: 0755 -29031113 深圳市钲铭科电子有限公司 SM7525 Primary Side Feedback Controlling Switch v1.6 GOSTON ELECTRONICS CO.,LTD PCB Layout Precautions Thermal Copper Area Pin 5 and 6 of IC need copper to dissipate, which means shopping copper in the bottom layer and the surface layer is necessary to reduce temperature and improve performance. The distance between DRAIN pin wiring and transformer should be as short as possible. It is appropriate to keep small loop area and no big area copper. FB pin wiring should be away from high-voltage loop with more than 1mm spacing to avoid interference. Mail : [email protected] Tel: 0755 -27593075 Address: 3F,SSMEC Bldg.,15 South 1st Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen. Note: The latest datasheet is subject to the web(www.dianyuanic.com). -6- Fax: 0755 -29031113 深圳市钲铭科电子有限公司 SM7525 Primary Side Feedback Controlling Switch v1.6 GOSTON ELECTRONICS CO.,LTD Typical Application Circuit SM7525 18V/300mA LED high-end lighting application circuit D6 T1 C2 5 GND 6 GND 7 DRAIN R2 R5 C3 DC+ R4 DC- 4 Y1 R3 VCC 3 1 FB CS D3 D4 E3 C1 SM7525 E1 E2 U1 ACin NC R6 F1 2 D1 D2 8 DRAIN L1 D5 EMI Component Absorbing Circuit R1 EMI Component Schematic： BOM Diagram： Symbol Parameters Bit Number Parameters D1、D2、D3、D4、 RS1M D5 C1 1uF/16V D6 ES1J C2 15pF/16V R1 1.5Ω/1206 C3 102/1KV R2 39K U1 SM7525 R3 1M/1206 F1 0.5A/250V R4、R6 20K/1206 T1 EE13 R5 120K/1206 L1 2.2mH/1W E1、E2 4.7uf/400V Y1 102/250V E3 10uF/35V Transform parameters; 8 1 5 4 1 N2 2 1 NC N3 N1 NC NC D o tte d te rm in a l N 3 (N C ٛ N 2 (2 ٛ N 1 (1 ٛ N C ) Φ 0 .2 5 * 1 * 3 6 T 1 ) Φ 0 .1 7 * 1 * 1 4 0 T N C ) Φ 0 .1 7 * 1 O v e r a ll c o r e N o te ： B o tto m V ie w 1 . E E 1 3 (4 + 4 ), H o riz o n ta l P C 4 0 2 . P rim a ry In d u c ta n c e L p = 2 .0 m H ， L e a k a g e In d u c ta n c e : < 5 % o f L p 3 . L e a k a g e C u rr e n t( P rim a ry to S e c o n d ) < 2 m A /6 0 s @ 3 0 0 0 V A C 4 . L e a k a g e C u rr e n t ( P rim a ry to M a g n e tic c o re ) < 2 m A /6 0 s @ 3 0 0 0 V A C 5 . L e a k a g e C u rr e n t ( S e c o n d to M a g n e tic c o re ) < 2 m A /6 0 s @ 3 0 0 0 V A C Mail : [email protected] Tel: 0755 -27593075 Address: 3F,SSMEC Bldg.,15 South 1st Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen. Note: The latest datasheet is subject to the web(www.dianyuanic.com). -7- Fax: 0755 -29031113 深圳市钲铭科电子有限公司 SM7525 Primary Side Feedback Controlling Switch v1.6 GOSTON ELECTRONICS CO.,LTD SM7525 60V/100mA BUCK-Boost Power Solution Schematic: F1 DC - GND GND 5 7 DRAIN 8 DRAIN C3 R2 L1 U1 6 D1 DB1 AC SM7525 C1 R1 R4 4 VCC 3 NC 2 FB CS 1 C4 R3 C2 DC + BOM Diagram： Symbol Parameters Bit Number Parameters DB1 MB6S C2 1uF D1 ES1J C3 15pF R1 1.6Ω/1206 C4 10uF/1206 R2 75K F1 10R Resistance R3 2M/1206 L1 2.4mh/Saturation Current>400mA R4 120K U1 SM7525 C1 6.8uf/400V Winding Mail : [email protected] Tel: 0755 -27593075 Address: 3F,SSMEC Bldg.,15 South 1st Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen. Note: The latest datasheet is subject to the web(www.dianyuanic.com). -8- Fax: 0755 -29031113 深圳市钲铭科电子有限公司 SM7525 Primary Side Feedback Controlling Switch v1.6 GOSTON ELECTRONICS CO.,LTD SM7525 Conduction Pictures Line L： Mail : [email protected] Tel: 0755 -27593075 Address: 3F,SSMEC Bldg.,15 South 1st Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen. Note: The latest datasheet is subject to the web(www.dianyuanic.com). -9- Fax: 0755 -29031113 深圳市钲铭科电子有限公司 SM7525 Primary Side Feedback Controlling Switch v1.6 GOSTON ELECTRONICS CO.,LTD Line N： Mail : [email protected] Tel: 0755 -27593075 Address: 3F,SSMEC Bldg.,15 South 1st Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen. Note: The latest datasheet is subject to the web(www.dianyuanic.com). - 10 - Fax: 0755 -29031113 深圳市钲铭科电子有限公司 SM7525 Primary Side Feedback Controlling Switch v1.6 GOSTON ELECTRONICS CO.,LTD Package: SOP8 Mail : [email protected] Tel: 0755 -27593075 Address: 3F,SSMEC Bldg.,15 South 1st Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen. Note: The latest datasheet is subject to the web(www.dianyuanic.com). - 11 - Fax: 0755 -29031113