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SG5841J — Highly Integrated Green-Mode PWM Controller
October 2010
SG5841J — Highly Integrated Green-Mode PWM
Controller
Features
Green-Mode PWM Controller
Low Startup Current : 14µA
Low Operating Current: 4mA
Programmable PWM Frequency with Hopping
Peak-Current-Mode Control
Cycle-by-Cycle Current Limiting
Synchronized Slope Compensation
Leading-Edge Blanking (LEB)
Constant Output Power Limit
Totem Pole Output with Soft Driving
V
DD
Over-Voltage Clamping
Programmable Over-Temperature Protection (OTP)
Internal Open-Loop Protection
V
DD
Under-Voltage Lockout (UVLO)
GATE Output Maximum Voltage Clamp:18V
Description
The highly integrated SG5841/J series of PWM
controllers provides several features to enhance the
performance of flyback converters.
To minimize standby power consumption, a proprietary
green-mode function provides off-time modulation to
continuously decrease the switching frequency at light-
load conditions. This green-mode function enables the
power supply to meet international power conservation
requirements. To further reduce power consumption,
SG5841/J is manufactured using the BiCMOS process.
This allows a low startup current, around 14µA, and an
operating current of only 4mA. As a result, a large
startup resistance can be used.
The built-in synchronized slope compensation achieves
stable peak-current-mode control. The proprietary
internal sawtooth power-limiter ensures a constant
output power limit over a wide range of AC input
voltages, from 90V
AC
to 264V
AC
.
SG5841/J provides many protections. In addition to
cycle-by-cycle current limiting, the internal open-loop
protection circuit ensures safety should an open-loop or
output-short-circuit failure occur. PWM output is
disabled until V
DD
drops below the UVLO lower limit,
then the controller restarts. An external NTC thermistor
can be applied for over-temperature protection.
SG5841/J is available in an 8-pin DIP or SOP package.
Applications
General-purpose, switch-mode, power supplies and
flyback power converters, including:
Power Adapters
Open-Frame SMPS
Ordering Information
Part Number
SG5841JSZ
SG5841JSY
SG5841SZ
SG5841SY
Ambient Operating
Temperature Range
-20 to +85°C
-20 to +85°C
-20 to +85°C
-20 to +85°C
Frequency
Hopping
Yes
Yes
No
No
Package
8-Pin Small Outline Package (SOP)
8-Pin Small Outline Package (SOP)
8-Pin Small Outline Package (SOP)
8-Pin Small Outline Package (SOP)
© 2006 Fairchild Semiconductor Corporation
SG5841J • Rev. 1.3.5
www.fairchildsemi.com
SG5841J — Highly Integrated Green-Mode PWM Controller
Typical Application
Figure 1. Application Diagram
Block Diagram
Figure 2. Block Diagram
© 2006 Fairchild Semiconductor Corporation
SG5841J • Rev. 1.3.5
www.fairchildsemi.com
2
SG5841J — Highly Integrated Green-Mode PWM Controller
Marking Information
SG5841HTP
XXXX XXXXYWW
marking for SG5841JSZ (pb-free)
marking for SG5841JDZ (pb-free)
marking for SG5841SZ (pb-free)
marking for SG5841DZ (pb-free)
H:
J = with Frequency Hopping
Null = without Frequency Hopping
T:
D = DIP, S = SOP
P:
Z = Lead Free
Null = regular package
XX XXXXXX
: Wafer Lot
Y:
Year;
WW
: Week
V:
Assembly Location
ZXYTT
5841/J
TPM
marking for SG5841JSY (green-compound)
marking for SG5841SY (green-compound)
F: Fairchild Logo
Z:Plant Code
X:1 Digit Year Code
Y:1 Digit Week Code
TT:2 Digit Die Run Code
T: Package Type (D:DIP, S:SOP)
P:Y = Green Package
M:Manufacturing Flow Code
Figure 3. Top Mark
© 2006 Fairchild Semiconductor Corporation
SG5841J • Rev. 1.3.5
www.fairchildsemi.com
3
SG5841J — Highly Integrated Green-Mode PWM Controller
Pin Configuration
GND
FB
VIN
RI
GATE
VDD
SENSE
RT
Figure 4. Pin Configuration
Pin Definitions
Pin #
1
2
Name
GND
FB
Function
Ground
Feedback
Ground.
Description
The signal from the external compensation circuit is fed into this pin. The PWM
duty cycle is determined in response to the signal from this pin and the current-
sense signal from pin 6. If FB voltage exceeds the threshold, the internal
protection circuit disables PWM output after a predetermined delay time.
3
VIN
For startup, this pin is pulled HIGH to the rectified line input via a resistor. Since
Startup Input the startup current requirement is very small, a large startup resistance is used to
minimize power loss.
Reference
Setting
A resistor connected from the RI to GND provides a constant current source. This
determines the center PWM frequency. Increasing the resistance reduces PWM
frequency. Using a 26KΩ resistor results in a 65KHz center PWM frequency.
4
RI
5
RT
For over-temperature protection. An external NTC thermistor is connected from
Temperature this pin to the GND pin. The impedance of the NTC decreases at high
temperatures. Once the voltage of the RT pin drops below a fixed limit, PWM
Detection
output is disabled.
Current
Sense
Power
Supply
Driver Output
Current sense. The sensed voltage is used for peak-current-mode control and
cycle-by-cycle current limiting.
Power supply. If V
DD
exceeds a threshold, the internal protection circuit disables
PWM output.
The totem-pole output driver for the power MOSFET, which is internally clamped
below 18V.
6
7
8
SENSE
VDD
GATE
© 2006 Fairchild Semiconductor Corporation
SG5841J • Rev. 1.3.5
www.fairchildsemi.com
4
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