SM7525 [SMSC]
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.;
| 型号： | SM7525 |
| 厂家： | 
SMSC CORPORATION |
| 描述： | 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. |
| 文件： | 总11页 (文件大小：2894K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
深圳市
科 子有限公司
SM7525 Primary Side Feedback Controlling Switch
GOSTON ELECTRONICS CO.,LTD
v1.6
SM7525
General Description
Features
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.
z
Topological structure support:
Fly-back and low-cost BUCK-
Boost
Integrated 730V hybrid techno-
logy
Universal input voltage:
85Vac~265Vac
Constant current precision less
than ±5%
z
z
z
z
z
Universal voltage compatible
with 1~5W
Pin Figure
SunMoon patented no auxiliary
winding of primary side feed-
back control technology without
coupler, 431 and other compo-
nents.
z
z
z
No loop compensation
Built-in LEB circuit
Cycle by cycle peak current
limiting
z
z
z
Output open/short circuit
Built-in soft-start
Built-in overvoltage protection
and short circuit protection
Package：SOP8
SOP8
Output Power Meter
z
85Vac～265Vac
180Vac～265Vac
Input Voltage
Output Power
1~5W
5~7W
Applications
Typical Application
LED lighting driver
AC
DC
SM7525
Absorbing
Circuit
:
sale@sz-ledpower.cn
Mail
Tel: 0755 -27593075
Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen.
Fax: 0755 -29031113
st
Address: 3F,SSMEC Bldg.,15 South 1
Note: The latest datasheet is subject to the web(www.dianyuanic.com).
-
- 1 -
深圳市
科 子有限公司
SM7525 Primary Side Feedback Controlling Switch
GOSTON ELECTRONICS CO.,LTD
v1.6
Pin Schematics
CS
FB
DRAIN
1
2
3
4
8
7 DRAIN
SM7525
NC
GND
GND
6
5
VCC
SOP8
Pin Description
Symbol
Pin Number Pin Description
CS
FB
1
2
Primary Side Peak Current Detection Port
Output Voltage Feedback Port
NC
3
No Connection
VDD
GND
DRAIN
4
Internal Power Supply Voltage Port
Ground
5,6
7.8
Open-drain of MOSFET
:
sale@sz-ledpower.cn
Mail
Tel: 0755 -27593075
Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen.
Fax: 0755 -29031113
st
Address: 3F,SSMEC Bldg.,15 South 1
Note: The latest datasheet is subject to the web(www.dianyuanic.com).
-
- 2 -
深圳市
科 子有限公司
SM7525 Primary Side Feedback Controlling Switch
GOSTON ELECTRONICS CO.,LTD
v1.6
Limiting Values
Limiting Parameters (TA= 25℃)
Symbol
VDD
VFB
Description
Range
Unit
V
Operating Voltage
FB Input Voltage
CS Input Voltage
Operating Temperature
Storage Temperature
-0.3~6
~
V
VCS
-0.3~7.0
-20~125
-40~150
V
TA
℃
℃
Tstg
VESD
HBM
4
KV
Rθja
Vds
Thermal Resistance
65
℃/W
Drain Source Breakdown Voltage
-0.3~730
V
Electrical Operating Parameters
((No special instruction，normal condition TA=25℃，VDD=6V)
Range
Symbol
Description
Unit
Min
Type
-250
6
Max
ICC
Vcc
Vcs
Static Current
uA
V
Power Supply Voltage
Current Detection Threshold
Leading Edge Blanking Time
620
450
mV
ns
TLEB
FB
Minimum
Threshold
VFBMIN
300
mV
Value
VFBMAX
TDEM_MIN
DMAX
FB Overvoltage Threshold
Minimum Degaussing Time
4
5
V
us
Maximum Duty Cycle
On-Resistance
42
15
%
RDSON
Ohm
Drain Source Breakdown
Voltage
BVD_SS
730
4
V
V
Vcc under-voltage protection
threshold
Vcc_uvlo
:
sale@sz-ledpower.cn
Mail
Tel: 0755 -27593075
Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen.
Fax: 0755 -29031113
st
Address: 3F,SSMEC Bldg.,15 South 1
Note: The latest datasheet is subject to the web(www.dianyuanic.com).
-
- 3 -
深圳市
科 子有限公司
SM7525 Primary Side Feedback Controlling Switch
GOSTON ELECTRONICS CO.,LTD
v1.6
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 × IP
（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 = ×LP ×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：
4
FSW
=
(4)
7×TDEMAG
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%.
:
sale@sz-ledpower.cn
Mail
Tel: 0755 -27593075
Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen.
Fax: 0755 -29031113
st
Address: 3F,SSMEC Bldg.,15 South 1
Note: The latest datasheet is subject to the web(www.dianyuanic.com).
-
- 4 -
深圳市
科 子有限公司
SM7525 Primary Side Feedback Controlling Switch
GOSTON ELECTRONICS CO.,LTD
v1.6
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.
:
sale@sz-ledpower.cn
Mail
Tel: 0755 -27593075
Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen.
Fax: 0755 -29031113
st
Address: 3F,SSMEC Bldg.,15 South 1
Note: The latest datasheet is subject to the web(www.dianyuanic.com).
-
- 5 -
深圳市
科 子有限公司
SM7525 Primary Side Feedback Controlling Switch
GOSTON ELECTRONICS CO.,LTD
v1.6
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.
:
sale@sz-ledpower.cn
Mail
Tel: 0755 -27593075
Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen.
Fax: 0755 -29031113
st
Address: 3F,SSMEC Bldg.,15 South 1
Note: The latest datasheet is subject to the web(www.dianyuanic.com).
-
- 6 -
深圳市
科 子有限公司
SM7525 Primary Side Feedback Controlling Switch
GOSTON ELECTRONICS CO.,LTD
v1.6
Typical Application Circuit
SM7525 18V/300mA LED high-end lighting application circuit
D6
E3
T1
DC+
DC-
L1
R4
D1 D2
C2
R6
R5 C3
2
R
F1
C1
Y1
SM7525
E1 E2
U1
ACin
R3
D5
EMI Component
D3 D4
Absorbing
Circuit
R1
EMI Component
Schematic：
BOM Diagram：
Symbol
Parameters
Bit Number
C1
Parameters
1uF/16V
D1、D2、D3、D4、 RS1M
D5
D6
ES1J
C2
C3
U1
F1
T1
L1
Y1
15pF/16V
102/1KV
SM7525
0.5A/250V
EE13
R1
1.5Ω/1206
39K
R2
R3
1M/1206
20K/1206
120K/1206
4.7uf/400V
10uF/35V
R4、R6
R5
2.2mH/1W
102/250V
E1、E2
E3
Transform parameters;
8
5
1
4
1
N 2
2
1
N C
N C
N 3
N 1
N ote：
B ottom V iew
N C
1. E E 13(4+ 4), H orizontal P C 40
2. P rim ary Inductance Lp=2.0m H ，Leakage
Inductance : <5% of Lp
D otted term inal
3. Leakage C urrent( P rim ary to S econd)
<2m A /60s@ 3000V A C
N 3(N C ٛ
N 2 (2ٛ
N C ) Φ0.25*1*36T
1 ) Φ0.17*1*140 T
4. Leakage C urrent ( P rim ary to M agnetic core)
<2m A /60s @ 3000V A C
N 1 (1 ٛ
N C ) Φ0.17*1 O verall core
5. Leakage C urrent ( S econd to M agnetic core )
<2m A /60s @ 3000V A C
:
sale@sz-ledpower.cn
Mail
Tel: 0755 -27593075
Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen.
Fax: 0755 -29031113
st
Address: 3F,SSMEC Bldg.,15 South 1
Note: The latest datasheet is subject to the web(www.dianyuanic.com).
-
- 7 -
深圳市
科 子有限公司
SM7525 Primary Side Feedback Controlling Switch
GOSTON ELECTRONICS CO.,LTD
v1.6
SM7525 60V/100mA BUCK-Boost Power Solution
Schematic:
DC -
F1
D1
DB1
R2
R3
C3
L1
AC
SM
752 5
C1
R4
C4
C2
R1
DC +
BOM Diagram：
Symbol
Parameters
MB6S
Bit Number
Parameters
1uF
DB1
D1
C2
C3
C4
F1
ES1J
15pF
R1
1.6Ω/1206
75K
10uF/1206
10R
R2
Winding
Resistance
R3
2M/1206
L1
2.4mh/Saturation
Current>400mA
SM7525
R4
C1
120K
U1
6.8uf/400V
:
sale@sz-ledpower.cn
Mail
Tel: 0755 -27593075
Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen.
Fax: 0755 -29031113
st
Address: 3F,SSMEC Bldg.,15 South 1
Note: The latest datasheet is subject to the web(www.dianyuanic.com).
-
- 8 -
深圳市
科 子有限公司
SM7525 Primary Side Feedback Controlling Switch
GOSTON ELECTRONICS CO.,LTD
v1.6
SM7525 Conduction Pictures
Line L：
:
sale@sz-ledpower.cn
Mail
Tel: 0755 -27593075
Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen.
Fax: 0755 -29031113
st
Address: 3F,SSMEC Bldg.,15 South 1
Note: The latest datasheet is subject to the web(www.dianyuanic.com).
-
- 9 -
深圳市
科 子有限公司
SM7525 Primary Side Feedback Controlling Switch
GOSTON ELECTRONICS CO.,LTD
v1.6
Line N：
:
sale@sz-ledpower.cn
Mail
Tel: 0755 -27593075
Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen.
Fax: 0755 -29031113
st
Address: 3F,SSMEC Bldg.,15 South 1
Note: The latest datasheet is subject to the web(www.dianyuanic.com).
-
- 10 -
深圳市
科 子有限公司
SM7525 Primary Side Feedback Controlling Switch
GOSTON ELECTRONICS CO.,LTD
v1.6
Package:
SOP8
:
sale@sz-ledpower.cn
Mail
Tel: 0755 -27593075
Blvd.,South Area,Shenzhen High tech Industrial Park,Nanshan Dist.,Shenzhen.
Fax: 0755 -29031113
st
Address: 3F,SSMEC Bldg.,15 South 1
Note: The latest datasheet is subject to the web(www.dianyuanic.com).
-
- 11 -
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