February 2009
SG6859D
Features
Low-Cost, Green-Mode PWM Controller for Flyback Converters
Description
This highly integrated PWM controller provides several
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 meet
even the strictest power conservation requirements.
The BiCMOS fabrication process enables reducing the
startup current to 9 A and the operating current to 3mA.
To further improve power conservation, a large startup
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 (90V
AC
to 264V
AC
). Pulse-by-pulse current
limiting ensures safe operation during short-circuits.
To protect the external power MOSFET from damage by
supply over voltage, the SG6859Ds output driver is
clamped at 17V. SG6859D controllers can be used to
improve the performance and reduce the production
cost of power supplies. The best choice for replacing
linear and RCC-mode power adapters. Available in 8-
pin DIP and 6-pin SSOT-6 packages.
Green-Mode PWM
Supports the Blue Angel Standard
Low Startup Current: 9 A
Low Operating Current: 3mA
300mA Driving Capability
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
V
DD
Over-Voltage Protection (Auto Restart)
Gate Output Voltage Clamped at 17V
Low Cost
Few External Components Required
Small SSOT-6 Package
Applications
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 auxiliary
supplies, home appliances, and consumer electronics
Replacements for linear transformers and RCC SMPS
PC 5V standby power
Ordering Information
Part Number
SG6859DTY
SG6859DDY
Operating Temperature Range
-40 to +105 C
Package
SSOT-6
DIP-8
Eco Status
Green
Packing Method
Tape & reel
Tube
For Fairchild’s definition of “green” Eco Status, please visit:
http://www.fairchildsemi.com/company/green/rohs_green.html.
© 2008 Fairchild Semiconductor Corporation
SG6859D Rev. 1.0.0
www.fairchildsemi.com
SG6859D Low-Cost, Green-Mode PWM Controller for Flyback Converters
Application Diagram
SG6859D
Figure 1. Typical Application
Internal Block Diagram
OSC
Generator
Figure 2. Functional Block Diagram
© 2008 Fairchild Semiconductor Corporation
SG6859D Rev. 1.0.0
2
www.fairchildsemi.com
Marking Information
SG6859D Low-Cost, Green-Mode PWM Controller for Flyback Converters
XXXX: ABBK=SG6859D
T : Die Run Code
. . .
: Year Code
- - - : Week Code
*Marking for SG6859DTY (Green compound)
F-
Fairchild Logo
Z- Plant Code
X- 1 Digit Year Code
Y- 1 Digit Week Code
TT: 2 Digits die Run Code
T: Package Type (D=DIP)
P: Y: Green Package
M: Manufacture Flow Code
ZXYTT
6859D
TPM
*Marking for SG6859DDY (Green compound)
Figure 3. Top Mark
Pin Configurations
Figure 4. 8-Pin DIP
Figure 5. 6-Pin SSOT
Pin Definitions
DIP
Pin #
1
2
3
4
4
SSOT
Pin #
6
5
Name
GATE
VDD
NC
SENSE
Description
The totem-pole output driver for driving the power MOSFET.
Power Supply.
No Connection.
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 provides current amplitude information for current-mode control.
A resistor connected from the RI pin to ground generates a constant current source
used to charge an internal capacitor and determine the switching frequency.
Increasing the resistance reduces the amplitude of the current source and the
switching frequency. A 95k resistor R
I
results in a 50 A constant current I
I
and a
65kHz switching frequency.
No Connection.
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.
Ground.
www.fairchildsemi.com
5
3
RI
6
7
8
2
1
NC
FB
GND
© 2008 Fairchild Semiconductor Corporation
SG6859D Rev. 1.0.0
3
SG6859D Low-Cost, Green-Mode PWM Controller for Flyback Converters
Absolute Maximum Ratings
Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be
operable above the recommended operating conditions and stressing the parts to these levels is not recommended.
In addition, extended exposure to stresses above the recommended operating conditions may affect device
reliability. The absolute maximum ratings are stress ratings only.
Symbol
V
VDD
V
FB
V
SENSE
T
J
JA
Parameter
DC Supply Voltage
(1, 2)
Min.
-0.3
-0.3
SSOT
DIP
-55
Max.
30
7.0
7.0
150
208.4
82.5
+150
+260
3.5
1.25
Unit
V
V
V
C
C/W
C/W
C
C
kV
kV
Input Voltage to FB Pin
Input Voltage to Sense Pin
Operating Junction Temperature
Thermal Resistance (Junction-to-Air)
Storage Temperature Range
Lead Temperature (Wave Soldering or IR, 10 Seconds)
Electrostatic Discharge
Human Body Model, JEDEC:JESD22-A114
Charged Device Model, JEDEC:JESD22-C101
T
STG
T
L
ESD
Notes:
1. All voltage values, except differential voltages, are given with respect to GND pin.
2. Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device.
© 2008 Fairchild Semiconductor Corporation
SG6859D Rev. 1.0.0
4
www.fairchildsemi.com
SG6859D Low-Cost, Green-Mode PWM Controller for Flyback Converters
Electrical Characteristics
Unless otherwise noted, V
DD
=15V and T
A
=25 C.
Symbol
V
DD
Section
V
DD-OP
V
DD-ON
V
DD-OFF
I
DD-ST
I
DD-OP
V
DD-OVP
Parameter
Continuously Operation Voltage
Turn-On Threshold Voltage
Turn-Off Threshold Voltage
Startup Current
Operating Supply Current
V
DD
Over-Voltage Protection Level
Conditions
Min.
Typ.
Max.
22
Units
V
V
V
A
mA
V
s
k
V
15.5
8.5
V
DD
=V
DD-ON
0.1V
V
DD
=15V, C
L
=1nF
Auto Restart
Auto Restart
24
16.5
9.5
9
3.0
25
125
5
17.5
10.5
15
3.5
26
t
D-VDDOVP
V
DD
Over-Voltage Protection Debounce
Feedback Input Section
Z
FB
V
FB-OPEN
V
FB-OL
t
D-OLP
V
FB-N
V
FB-G
V
FB-ZDC
S
G
Z
SENSE
t
PD
V
STHFL
V
STHVA
t
LEB
DCY
SAW
Input Impedance
FB Output High Voltage
FB Open-loop Trigger Level
Delay of FB Pin Open-loop Protection
Green-Mode Entry FB Voltage
Green-Mode Ending FB Voltage
Zero Duty-Cycle Input Voltage
Green-Mode Modulation Slope
Input Impedance
Delay to Output
Flat Threshold Voltage for Current Limit
Valley Threshold Voltage for Current Limit
Leading-Edge Blanking Time
Duty Cycle of SAW Limit
Center Frequency
Hopping Range
60
R
I
=95k
40
10
45
0.95
0.75
250
65
1.01
0.80
300
30
65
4
4
22
5
5
70
85
1.06
0.85
350
R
I
=95k
FB Pin Open
5
4.3
53
2.60
4.6
58
2.85
2.2
1.8
60
80
4.9
63
3.10
V
ms
V
V
V
Hz/mV
k
ns
V
V
ns
%
Current-Sense Section
Oscillator Section
f
OSC
t
HOP
f
OSC-G
f
DV
f
DT
Frequency
R
I
=95k
R
I
=95k
R
I
=95k
V
DD
=13.5 to 22V
T
A
=-20 to 85°C
kHz
ms
kHz
%
%
Hopping Period
Green-Mode Frequency
Frequency Variation vs. V
DD
Deviation
Frequency Variation vs. Temperature
Deviation
Maximum Duty Cycle
Output Voltage Low
Output Voltage High
Rising Time
Falling Time
Output Clamp Voltage
Output Section
DCY
MAX
V
GATE-L
V
GATE-H
t
r
t
f
V
GATE-
CLAMP
65
V
DD
=15V, I
O
=20mA
V
DD
=13.5V, I
O
=20mA
V
DD
=15V, C
L
=1nF
V
DD
=15V, C
L
=1nF
V
DD
=22V
8
80
35
16
70
75
1.4
%
V
V
ns
ns
V
150
55
17
180
75
18
© 2008 Fairchild Semiconductor Corporation
SG6859D Rev. 1.0.0
5
www.fairchildsemi.com
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