Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters
SG6858
FEATURES
Green-mode PWM
Supports the “Blue Angel” standard
Low start-up current (10uA)
Low operating current (2.5mA)
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
Gate output voltage clamped at 17V
Low cost
Few external components required
Small SOT-26 and DIP-8 packages available
DESCRIPTION
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.
The BiCMOS fabrication process enables reducing the
start-up current to 10uA, and the operating current to
2.5mA. 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.
To protect the external power MOSFET from being
damaged by supply over voltage, the SG6858’s output
driver is clamped at 17V. SG6858 controllers can be used
to improve the performance and reduce the production
cost of power supplies. The SG6858 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.
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 other
auxiliary supplies, home appliances, and consumer
electronics
Replacements for linear transformers and RCC
SMPS
PC 5V standby power.
TYPICAL APPLICATION
© System General Corp.
Version 1.1(IAO33.0045.B1)
-1-
www.sg.com.tw
Nov. 3, 2006
Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters
SG6858
MARKING DIAGRAMS
AAI:
SG6858
m:
Mask Version
w:
Week code A~Z=W1~W26
A~Z=W27~W52
: Lead Free Package
PIN CONFIGURATION
SOT-26
GND
FB
RI
DIP-8
D:
D=DIP
P:
Z=Lead Free
Null=Regular Package
XXXXXXXX:
Wafer Lot
Y:
Year;
WW:
Week
V:
Assembly Location
GATE
VDD
NC
SENSE
GND
FB
NC
RI
GATE
VDD
SENSE
AAImw
SG6858DP
XXXXXXXXYWWV
ORDERING INFORMATION
Part Number
SG6858TZ
SG6858DZ
Package
6-Pin SOT-26
8-pin DIP-8
PIN DESCRIPTIONS
Name
GATE
VDD
NC
SENSE
Pin No.
Type
DIP-8 / (SOT-26)
1 / (6)
2 / (5)
3
4 / (4)
Analog
Input
Driver
Output
Supply
Function
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.
A resistor connected from the RI pin to ground will generate a constant current source for
the SG6858. This current is used to charge an internal capacitor, to determine the
source and reduce the switching frequency. A 95kΩ resistor R
i
results in a 50uA constant
current I
i
and a 70kHz switching frequency.
NC pin.
Analog
RI
5 / (3)
ut
NC
FB
GND
6
7 / (2)
8 / (1)
Analog
Input
Supply
Input/Outp switching frequency. Increasing the resistance will reduce the amplitude of the current
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.
© System General Corp.
Version 1.1(IAO33.0045.B1)
-2-
www.sg.com.tw
Nov. 3, 2006
Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters
SG6858
ABSOLUTE MAXIMUM RATINGS
Symbol
V
VDD
V
FB
V
SENCE
T
J
R
θ
JA
T
STG
T
L
V
ESD-HBM
V
ESD-MM
Parameter
DC Supply Voltage *
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)
ESD Capability, HBM Model
ESD Capability, Machine Model
Value
30
-0.3 to 7
-0.3 to 7
-40 to +125
SOT
DIP
-55 to +150
260
3.0
200
208.4
82.5
Unit
V
V
V
°C
°C/W
°C/W
°C
°C
kV
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
V
DD
T
A
Parameter
DC Supply Voltage
Operating Ambient Temperature
Value
≦22
-20 to 85
Unit
V
°C
* For proper operation
ELECTRICAL CHARACTERISTICS (V
DD
=15V, T
A
= 25°C, unless noted)
VDD Section
Symbol
V
DD-OP
V
DD-ON
V
DD-OFF
I
DD-ST
I
DD-OP
V
DD-OVP
t
D-VDDOVP
V
DD-G OFF
Parameter
Continuously Operation Voltage
Turn-on Threshold Voltage
Turn-off Threshold Voltage
Startup Current
Operating Supply Current
VDD Over-voltage-protection level
VDD Over-voltage-protection Debounce
V
DD
Low-threshold Voltage to Exit
Green-off Mode
Test Condition
Min.
15.5
10.5
Typ.
16.5
11.5
10
2.5
Max.
22
17.5
12.5
20
3.5
26
200
V
DD-OFF
+
1.25
Unit
V
V
V
uA
mA
V
us
V
V
DD
=V
DD-ON
– 0.1V
V
DD
=15V,
GATE with 1nF to GND
24
50
V
DD-OFF
+
0.95
25
125
V
DD-OFF
+
1.1
© System General Corp.
Version 1.1(IAO33.0045.B1)
-4-
www.sg.com.tw
Nov. 3, 2006
Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters
SG6858
Feedback Input Section
Symbol
A
V
Z
FB
V
FB-OPEN
V
FB-N
V
FB-G
S
G
Parameter
FB Input to Current Comparator Attenuation
Input Impedance
FB Output High Voltage
Green-mode Entry FB Voltage
Green-mode Ending FB Voltage
Green-mode Modulation Slope
Test Condition
Min.
Typ.
2/5
5
Max.
Unit
V/V
KΩ
4.5
5
2.85
2.20
5.5
V
V
V
Hz/mV
R
I
=95kΩ
75
Current Sense Section
Symbol
Z
SENSE
t
PD
V
STHFL
V
STHVA
t
LEB
DCY
SAW
Parameter
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
Test Condition
Min.
10
Typ.
60
0.96
Max.
100
0.85
350
Unit
kΩ
ns
V
V
ns
%
0.75
250
Max. Duty Cycle
0.80
300
45
Oscillator Section
Symbol
F
OSC
F
OSC-G
F
DV
F
DT
Parameter
Frequency
Green-mode Frequency
Frequency Variation versus V
DD
Deviation
Frequency Variation versus Temp. Deviation
Test Condition
R
I
=95kΩ
R
I
=95kΩ
V
DD
=12 to 22V
T
A
= -20 to 85°C
Min.
65
0
Typ.
70
22
0.02
Max.
75
2
2
Unit
kHz
kHz
%
%
Output Section
Symbol
DCY
MAX
V
GATE-L
V
GATE-H
tr
tf
V
GATE-CLAMP
Parameter
Maximum Duty Cycle
Output Voltage Low
Output Voltage High
Rising Time
Falling Time
Output Clamp Voltage
Test Condition
V
DD
=15V, I
o
=20mA
V
DD
=15V, I
o
=-20mA
V
DD
=15V, C
L
=1nF
V
DD
=15V, C
L
=1nF
V
DD
=22V
Min.
70
8
150
35
16
Typ.
75
Max.
80
1.5
Unit
%
V
V
ns
ns
V
200
55
17
250
75
18
© System General Corp.
Version 1.1(IAO33.0045.B1)
-5-
www.sg.com.tw
Nov. 3, 2006
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