SG6859TZ [FAIRCHILD]
Low Cost Green-Mode PWM Controller for Flyback Converters; 低成本绿色模式PWM控制器，用于反激式转换器
| 型号： | SG6859TZ |
| 厂家： | 
FAIRCHILD SEMICONDUCTOR |
| 描述： | Low Cost Green-Mode PWM Controller for Flyback Converters |
| 文件： | 总13页 (文件大小：473K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters
SG6859
FEATURES
DESCRIPTION
Green-Mode PWM
This highly integrated PWM controller provides
several special enhancements designed to meet the low
standby-power needs of low-power SMPS. To minimize
standby power consumption, the proprietary green-mode
function provides off-time modulation to linearly
decrease the switching frequency under light-load
conditions. This green-mode function enables the power
supply to easily meet even the strictest power
conservation requirements.
Supports the “Blue Angel” Standard
Low Start-up Current (9uA)
Low Operating Current (3mA)
Leading-Edge Blanking
Constant Output Power Limit
Universal Input
Built-in Synchronized Slope Compensation
Current Mode Operation
Cycle-by-cycle Current Limiting
Under Voltage Lockout (UVLO)
Programmable PWM Frequency with Frequency
Hopping
VDD Over Voltage Protection (Auto Restart)
Gate Output Voltage Clamped at 17V
Low Cost
Few External Components Required
Small SOT-26 and Dip 8 Packages
The BiCMOS fabrication process enables reducing
the start-up current to 9uA, and the operating current to
3mA. To further improve power conservation, a large
start-up resistance can be used. Built-in synchronized
slope compensation ensures the stability of peak current
mode control. Proprietary internal compensation provides
a constant output power limit over a universal AC input
range (90VAC to 264VAC). Pulse-by-pulse current limiting
ensures safe operation even during short-circuits.
APPLICATIONS
To protect the external power MOSFET from being
damaged by supply over voltage, the SG6859’s output
driver is clamped at 17V. SG6859 controllers can be used
to improve the performance and reduce the production
cost of power supplies. The SG6859 is the best choice for
replacing linear and RCC-mode power adapters. It is
available in 8-pin DIP and 6-pin SOT-26 packages.
General-purpose switching mode power supplies and
flyback power converters, such as
Battery chargers for cellular phones, cordless
phones, PDAs, digital cameras, and power tools
Power adapters for ink jet printers, video game
consoles, and portable audio players
Open-frame SMPS for TV/DVD standby and other
auxiliary supplies, home appliances, and consumer
electronics
Replacements for linear transformers and RCC
SMPS
PC 5V standby power.
TYPICAL APPLICATION
SG6859
© System General Corp.
Version 1.2.1(IAO33.0067.B2)
- 1 -
www.sg.com.tw • www.fairchildsemi.com
September 28,2007
Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters
SG6859
MARKING DIAGRAMS
PIN CONFIGURATION
AAJ: SG6859
M: Mask Version
SOT-26
W: Week code A~Z=W1~W26
GATE
VDD
GND
FB
AAJMW
A~Z=W27~W52
: Lead Free Package
SENSE
RI
DIP-8
T: D=DIP
P: Z =Lead Free
Null=Regular Package
XXXXXXXX: Wafer Lot
Y: Year; WW: Week
V: Assembly Location
GND
FB
GATE
VDD
SG6859TP
XXXXXXXXYWWV
NC
NC
RI
SENSE
ORDERING INFORMATION
Part Number
Pb-Free
Package
SG6859TZ
6-Pin SOT-26
SG6859DZ
8-Pin DIP-8
PIN DESCRIPTIONS
Pin No.
DIP-8(SOT-26)
Name
Type
Function
GATE
VDD
NC
1 / (6)
2 / (5)
3
Driver Output
Supply
The totem-pole output driver for driving the power MOSFET.
Power supply.
NC pin.
Current sense. This pin senses the voltage across a resistor. When the voltage
reaches the internal threshold, PWM output is disabled. This activates
over-current protection. This pin also provides current amplitude information for
current-mode control.
SENSE 4 / (4)
Analog Input
A resistor connected from the RI pin to ground will generate a constant current
source for the SG6859. This current is used to charge an internal capacitor, to
determine the switching frequency. Increasing the resistance will reduce the
amplitude of the current source and reduce the switching frequency. A 95kΩ
resistor Ri results in a 50uA constant current Ii and a 70kHz switching frequency.
NC pin.
Analog
RI
5 / (3)
Input/Output
NC
FB
6
Feedback. The FB pin provides the output voltage regulation signal. It provides
feedback to the internal PWM comparator, so that the PWM comparator can
control the duty cycle.
7 / (2)
Analog Input
Supply
GND
8 / (1)
Ground.
© System General Corp.
Version 1.2.1(IAO33.0067.B2)
- 2 -
www.sg.com.tw • www.fairchildsemi.com
September 28, 2007
Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters
SG6859
BLOCK DIAGRAM
© System General Corp.
Version 1.2.1(IAO33.0067.B2)
- 3 -
www.sg.com.tw • www.fairchildsemi.com
September 28, 2007
Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters
SG6859
ABSOLUTE MAXIMUM RATINGS
Symbol
VVDD
Parameter
DC Supply Voltage *
Value
30
Unit
V
VFB
Input Voltage to FB Pin
Input Voltage to Sense Pin
Operating Junction Temperature
-0.3 to 7
-0.3 to 7
150
V
VSENCE
TJ
V
°C
SOT
208.4
82.5
°C/W
°C/W
°C
R
Thermal Resistance (Junction to Air)
θJA
DIP
TSTG
Storage Temperature Range
-55 to +150
260
TL
Lead Temperature (Wave soldering or IR, 10 seconds)
ESD Capability, HBM Model
°C
VESD-HBM
VESD-MM
3.5
kV
ESD Capability, Machine Model
200
V
* All voltage values, except differential voltages, are given with respect to GND pin.
* Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device.
RECOMMENDED OPERATING CONDITIONS
Symbol
VDD
Parameter
DC Supply Voltage
Value
≦22
Unit
V
TA
Operating Ambient Temperature
-20 to +85
°C
* For proper operation.
ELECTRICAL CHARACTERISTICS (VDD = 15V; TA = 25°C)
VDD Section
Symbol
VDD-OP
Parameter
Test Condition
Min.
Typ.
Max.
22
Unit
V
Continuously Operation Voltage
Turn-On Threshold Voltage
Turn-Off Threshold Voltage
Startup Current
VDD-ON
VDD-OFF
IDD-ST
15.5
10.5
16.5
11.5
9
17.5
12.5
15
V
V
VDD=VDD-ON – 0.1V
VDD=15V,
µA
IDD-OP
Operating Supply Current
3
3.5
26
mA
GATE with 1nF to GND
(Auto Restart)
VDD-OVP
VDD Over-voltage-protection level
24
25
V
tD-VDDOVP
VDD Over-voltage-protection Debounce (Auto Restart)
VDD Low-threshold Voltage to Exit
Green-off Mode
125
µs
VDD-G OFF
VDD-OFF + 1
V
© System General Corp.
Version 1.2.1(IAO33.0067.B2)
- 4 -
www.sg.com.tw • www.fairchildsemi.com
September 28, 2007
Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters
SG6859
Feedback Input Section
Symbol
ZFB
Parameter
Input Impedance
Test Condition
Min.
Typ.
5
Max.
Unit
KΩ
V
VFB-OPEN
VFB-OL
tD-OLP
VFB-N
FB Output High Voltage
5
FB Open-loop Trigger Level
The delay time of FB pin Open Loop Protection
Green-Mode Entry FB Voltage
Green-Mode Ending FB Voltage
Green-Mode Modulation Slope
4.3
4.6
56
4.9
3.1
100
V
ms
V
2.6
40
2.85
2.20
75
VFB-G
V
SG
RI=95KΩ
Hz/mV
Current Sense Section
Symbol
ZSENSE
tPD
Parameter
Input Impedance
Test Condition
Min.
10
Typ.
Max.
Unit
KΩ
ns
V
Delay to Output
40
55
100
1.01
0.85
350
VSTHFL
VSTHVA
tLEB
Flat Threshold Voltage for Current Limit
Valley Threshold Voltage for Current Limit
Leading-Edge Blanking Time
Duty Cycle of SAW Limit
0.91
0.75
250
0.96
0.80
300
40
V
ns
%
DCYSAW
Oscillator Section
Symbol
Parameter
Test Condition
Min.
65
Typ.
70
Max.
75
Unit
Center Frequency
Hopping Range
FOSC
Normal PWM Frequency
RI=95KΩ
KHz
±4.9
3.7
THOP
FOSC-G
FDV
Hopping Period
RI=95KΩ
ms
KHz
%
Green-Mode Frequency
RI=95KΩ
22
Frequency Variation versus VDD Deviation
Frequency Variation versus Temp. Deviation
VDD=13.5 to 22V
TA=-20 to 85°C
0
0.02
2
2
FDT
%
Output Section
Symbol
DCYMAX
VGATE-L
Parameter
Maximum Duty Cycle
Test Condition
Min.
70
Typ.
75
Max.
80
Unit
%
Output Voltage Low
VDD=15V, Io=20mA
1.5
V
VGATE-H
Output Voltage High
Rising Time
VDD=13.5V, Io=20mA
VDD=15V, CL=1nF
VDD=15V, CL=1nF
VDD=22V
8
V
tr
150
55
ns
ns
V
tf
Falling Time
VGATE-CLAMP
Output Clamp Voltage
16
17
18
© System General Corp.
Version 1.2.1(IAO33.0067.B2)
- 5 -
www.sg.com.tw • www.fairchildsemi.com
September 28, 2007
Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters
SG6859
TYPICAL CHARACTERISTICS
Turn-On Threshold Voltage (VDD-ON) vs Temperature
Turn-Off Threshold Voltage (VDD-OFF) vs Temperature
17.0
14
13
16.8
12
16.6
11
16.4
10
16.2
9
8
16.0
-40
-40
-40
-25
-10
5
20
35
50
65
80
95
110
110
110
125
125
125
-40
-25
-10
5
20
35
50
65
80
95
110
110
110
125
125
125
Temperature (℃)
Temperature (℃)
Startup Current (IDD-ST) vs Temperature
Operating Supply Current (IDD-OP) vs Temperature
1.4
3.0
2.8
2.6
2.4
2.2
2.0
1.2
1.0
0.8
0.6
0.4
0.2
-40
-25
-10
5
20
35
50
65
80
95
-25
-10
5
20
35
50
65
80
95
Temperature (℃)
Temperature (
)
℃
Normal PWM Frequency (FOSC) vs Temperature
Maximum Duty Cycle (DCYMAX) vs Temperature
75.0
74.8
74.6
74.4
74.2
74.0
72.0
71.5
71.0
70.5
70.0
-25
-10
5
20
35
50
65
80
95
-40
-25
-10
5
20
35
50
65
80
95
Temperature (℃)
Temperature (℃)
© System General Corp.
Version 1.2.1(IAO33.0067.B2)
- 6 -
www.sg.com.tw • www.fairchildsemi.com
September 28, 2007
Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters
SG6859
Green-Mode Entry FB Voltage (VFB-N) vs Temperature
Green-Mode Ending FB Voltage (VFB-G) vs Temperature
3.2
2.30
3.0
2.28
2.8
2.6
2.4
2.2
2.26
2.24
2.22
2.20
-40
-25
-10
5
20
35
50
65
80
95
110
125
-40
-25
-10
5
20
35
50
65
80
95
110
125
Temperature (℃)
Temperature (℃)
Operating Supply Current vs VDD voltage
Leading-Edge Blanking Time (tLEB) vs Temperature
340
330
320
310
300
290
280
3.5
3.0
2.5
2.0
1.5
1.0
-40
-25
-10
5
20
35
50
65
80
95
110
125
12
13
14
15
16
17
18
19
20
21
22
23
24
Temperature (℃)
VDD (V)
© System General Corp.
Version 1.2.1(IAO33.0067.B2)
- 7 -
www.sg.com.tw • www.fairchildsemi.com
September 28, 2007
Product Specification
SG6859
Low Cost Green-Mode PWM Controller for Flyback Converters
Each time the power MOSFET is switched on, a
OPERATION DESCRIPTION
turn-on spike will inevitably occur at the sense-resistor.
To avoid premature termination of the switching pulse, a
320nsec leading edge blanking time is built in.
Conventional RC filtering can therefore be omitted.
During this blanking period, the current-limit comparator
is disabled and it cannot switch off the gate driver.
SG6859 devices integrate many useful designs into
one controller for low-power switch-mode power supplies.
The following descriptions highlight some of the features
of the SG6859 series.
Start-up Current
Constant Output Power Limit
The start-up current is only 9uA. Low start-up
current allows a start-up resistor with a high resistance
and a low-wattage to supply the start-up power for the
controller. A 1.5 MΩ, 0.25W, start-up resistor and a
10uF/25V VDD hold-up capacitor would be sufficient for
an AC-to-DC power adapter with a wide input range
(100VAC to 240VAC).
When the SENSE voltage across the sense resistor Rs
reaches the threshold voltage (around 0.96V), the output
GATE drive will be turned off following a short
propagation delay tPD
.
This propagation delay will introduce an additional
current proportional to tPD*Vin/Lp. The propagation delay
is nearly constant regardless of the input line voltage VIN.
Higher input line voltages will result in larger additional
currents. At high input line voltages, the output power
limit will be higher than at low input line voltages.
Operating Current
The operating current has been reduced to 3mA. The
low operating current results in higher efficiency and
reduces the VDD hold-up capacitance requirement.
To compensate for this output power limit variation
across a wide AC input range, the threshold voltage is
adjusted by adding a positive ramp.
Green-Mode Operation
The proprietary green-mode function provides
off-time modulation to linearly decrease the switching
frequency under light-load conditions. On-time is limited
to provide stronger protection against brownouts and
other abnormal conditions. The feedback current, which is
sampled from the voltage feedback loop, is taken as the
reference. Once the feedback current exceeds the
threshold current, the switching frequency starts to
decrease. This green-mode function dramatically reduces
power consumption under light-load and zero-load
conditions. Power supplies using the SG6859 can easily
meet even the strictest regulations regarding standby
power consumption.
This ramp signal rises from 0.80V to 0.96V, and then
flattens out at 0.96V. A smaller threshold voltage forces
the output GATE drive to terminate earlier.
This reduces the total PWM turn-on time and makes
the output power equal to that of low line input. This
proprietary internal compensation ensures a constant
output power limit for a wide AC input voltage range
(90VAC to 264VAC).
Under Voltage Lockout (UVLO)
The turn-on and turn-off thresholds of the SG6859
are fixed internally at 16.5V/11.5V. During start-up, the
hold-up capacitor must be charged to 16.5V through the
start-up resistor, so that the SG6859 will be enabled. The
hold-up capacitor will continue to supply VDD until power
can be delivered from the auxiliary winding of the main
transformer. VDD must not drop below 11.5V during this
start-up process. This UVLO hysteresis window ensures
that hold-up capacitor will be adequate to supply VDD
during start-up.
Oscillator Operation
A resistor connected from the RI pin to ground will
generate a constant current source for the SG6859. This
current is used to charge an internal capacitor. The
charge-time determines the internal clock speed and the
switching frequency. Increasing the resistance will reduce
the amplitude of the input current and reduce the
switching frequency. A 95kΩ resistor Ri results in a 50uA
constant current Ii and a 70kHz switching frequency. The
relationship between Ri and the switching frequency is:
6650
f
PWM =
(kHz )
RI (kΩ)
Leading-Edge Blanking
© System General Corp.
Version 1.2.1(IAO33.0067.B2)
- 8 -
www.sg.com.tw • www.fairchildsemi.com
September 28, 2007
Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters
SG6859
Gate Output
The SG6859 BiCMOS output stage is a fast totem
pole gate driver. Cross conduction has been avoided to
minimize heat dissipation, increase efficiency, and
enhance reliability. The output driver is clamped by an
internal 17V Zener diode in order to protect power
MOSFET transistors against undesired over-voltage gate
signals.
Built-in Slope Compensation
The sensed voltage across the current sense resistor
is used for current mode control and pulse-by-pulse
current limiting. Built-in slope compensation will
improve stability and prevent sub-harmonic oscillations
due to peak-current mode control. The SG6859 has a
synchronized, positively-sloped ramp built-in at each
switching cycle. The slope of the ramp is:
0.36× Duty
Duty(max.)
Noise Immunity
Noise from the current sense or the control signal can
cause significant pulse width jitter, particularly in
continuous-conduction mode. While slope compensation
helps alleviate these problems, further precautions should
still be taken. Good placement and layout practices should
be followed. Avoiding long PCB traces and component
leads, locating compensation and filter components near
the SG6859, and increasing the power MOS gate
resistance is advised.
© System General Corp.
Version 1.2.1(IAO33.0067.B2)
- 9 -
www.sg.com.tw • www.fairchildsemi.com
September 28, 2007
Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters
SG6859
REFERENCE CIRCUIT
L1
F1
1
2
L
BD1
C3
R3
R4
R1
R2
CX1
2
4
C1
C2
R5
L2
D4
T1
10
9
1,2
2
1
1
2
N
VO
R10
D1
Q1
C7
8
5
C8
D5
C9
U1
GND GATE
R7
1
2
3
6
5
4
1
7
3,4
FB
RI
VDD
GND
R15
SENSE
C6
C11
R9
R6
D2
R8
1
2
R11
C4
R13
U2
R14
C10
CY1
U3
1
R12
BOM
Reference
BD1
Component
BD 1A/500V
Reference
L2
Component
10uH 6mm
CX1 (Optional) XC 0.1uF
CY1 (Optional) YC 102P/400V (Y1)
CC 103P/500V
Q1
MOSFET 1A/600V
R 750KΩ 1206
R 47KΩ 1206
R 47Ω 1206
R1,R2
R3,R4
R5
C1
C2
C3
C4
C6
C7
C8
C9
C10
C11
D1
D2
D4
D5
F1
EC 10µF/400V 105°C
CC 102P/500V
EC 10µ/50V
R6
R 4.7Ω 1206
R 100Ω 0805
R 10Ω 1206
R7
CC 472P 0805
CC 102P/100V 1206
EC 470µ/10V 105°C
EC 220µ/10V 105°C
CC 222P 0805
N.C.
R8
(Optional)
R9
R 100KΩ 0805
R10
R11
R12
R13
R14
R15
T1
(Optional) R 10Ω 1206
R 100Ω 1/8W
R 33KΩ 0805
R 33KΩ 1/8W
R 4.7KΩ 0805
R 0Ω 0805
Diode FRI07
Diode FR102
Diode SB360
EE-16
(Optional)
ZD 6.8V 0.5W
R 1Ω/0.5W
U1
IC SG6859
PC817
U2
L1
20mH 6*8mm
U3
TL431
© System General Corp.
Version 1.2.1(IAO33.0067.B2)
- 10 -
www.sg.com.tw • www.fairchildsemi.com
September 28, 2007
Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters
SG6859
PACKAGE INFORMATION
8 PINS - DIP (D)
D
Θ
8
1
5
4
e
B
E
L
b1
b
e
Dimensions
Millimeters
Min.
Inches
Min.
Symbol
Typ.
Max.
Typ.
Max.
A
5.334
0.210
A1
0.381
3.175
0.015
0.125
A2
b
3.302
1.524
0.457
9.271
7.620
6.350
2.540
3.302
9.017
7˚
3.429
0.130
0.060
0.018
0.365
0.300
0.250
0.100
0.130
0.355
7˚
0.135
b1
D
9.017
6.223
10.160
6.477
0.355
0.245
0.400
0.255
E
E1
e
L
2.921
8.509
0˚
3.810
9.525
15˚
0.115
0.335
0˚
0.150
0.375
15˚
eB
θ˚
© System General Corp.
Version 1.2.1(IAO33.0067.B2)
- 11 -
www.sg.com.tw • www.fairchildsemi.com
September 28, 2007
Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters
SG6859
6 PINS - SOT (T)
D
Detail A
b
6
4
3
c
1
e
e1
θ
1
L
θ
L1
θ
1
Detail A
Dimensions
Millimeters
Min.
Inches
Min.
Symbol
Typ.
Max.
1.45
0.15
1.30
0.50
0.22
Typ.
Max.
0.057
0.006
0.051
0.020
0.009
A
A1
A2
b
0.90
0.30
0.08
1.15
0.036
0.011
0.003
0.045
c
D
2.90
2.80
1.60
0.95
1.90
0.45
0.60
0.25
0.114
0.110
0.063
0.037
0.075
0.018
0.024
0.010
E
E1
e
e1
L
0.30
0.60
0.020
0.024
L1
L2
R
0.10
0.10
0°
0.004
0.004
0°
R1
θ°
θ1°
0.25
8°
0.010
8°
4°
4°
5°
10°
15°
5°
10°
15°
© System General Corp.
Version 1.2.1(IAO33.0067.B2)
- 12 -
www.sg.com.tw • www.fairchildsemi.com
September 28, 2007
Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters
SG6859
© System General Corp.
Version 1.2.1(IAO33.0067.B2)
- 13 -
www.sg.com.tw • www.fairchildsemi.com
September 28, 2007
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