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SG5842A/SG5842JA — Highly Integrated Green-Mode PWM Controller
December 2009
SG5842A/SG5842JA — Highly Integrated Green-Mode
PWM Controller
Features
Green-Mode PWM Controller
Low Startup Current: 14µA
Low Operating Current: 4mA
Programmable PWM Frequency with Hopping
(SG5842JA)
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 Protection (OVP)
Programmable Over-Temperature Protection (OTP)
Internal Latch Circuit (OTP, OVP)
Internal Open-Loop Protection
V
DD
Under-Voltage Lockout (UVLO)
GATE Output Maximum Voltage Clamp: 18V
Description
The highly integrated SG5842A/JA 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. To
avoid acoustic-noise problems, the minimum PWM
frequency set above 22KHz. This green-mode function
enables the power supply to meet international power
conservation requirements. To further reduce power
consumption, SG5842A/JA 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
SG5842A/JA
built-in
synchronized
slope
compensation achieves stable peak-current-mode
control. SG5842JA integrates a frequency-hopping
function that helps reduce EMI emission of a power
supply with minimum line filters.
SG5842A/JA provides many protection functions. 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 starts again. As long as V
DD
exceeds about 24V, the internal OVP circuit is triggered.
An external NTC thermistor can be applied for over-
temperature protection.
SG5842A/JA is available in an 8-pin DIP or SOP
package.
Applications
General-purpose switch-mode power supplies and
flyback power converters, including:
Notebook Power Adapters
Open-Frame SMPS
© 2007 Fairchild Semiconductor Corporation
SG5842A/SG5842JA • Rev. 1.4.3
www.fairchildsemi.com
SG5842A/SG5842JA — Highly Integrated Green-Mode PWM Controller
Ordering Information
Part Number
SG5842JASZ
SG5842JADZ
SG5842JASY
SG5842ASZ
(Preliminary)
SG5842ASY
(Preliminary)
Operating
Temperature
Range
-40°C to +105°C
-40°C to +105°C
-40°C to +105°C
-40°C to +105°C
-40°C to +105°C
Eco
Status
RoHS
RoHS
Green
RoHS
Green
Package
8-Pin Small Outline Package (SOP)
8-Pin Dual Inline Package (DIP)
8-Pin Small Outline Package (SOP)
8-Pin Small Outline Package (SOP)
8-Pin Small Outline Package (SOP)
OTP
Latch
Yes
Yes
Yes
Yes
Yes
OVP Frequency
Latch Hopping
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
For Fairchild’s definition of Eco Status, please visit:
http://www.fairchildsemi.com/company/green/rohs_green.html.
Application Diagram
Figure 1. Application Diagram
© 2007 Fairchild Semiconductor Corporation
SG5842A/SG582JA • Rev. 1.4.3
www.fairchildsemi.com
2
SG5842A/SG5842JA — Highly Integrated Green-Mode PWM Controller
Block Diagram
Figure 2. Function Block Diagram
Marking Information
H:
J = with Frequency Hopping
Null = without Frequency
Hopping
T:
D = DIP, S = SOP
P:
Z = Lead Free
Null = Regular Package
XXXXXXXX:
Wafer Lot
Y:
Year;
WW:
Week
V:
Assembly Location
SG5842HATP
XXXXXXXXYWWV
Marking for SG5842JASZ (pb-free)
Marking for SG5842JADZ (pb-free)
Marking for SG5842ASZ (pb-free)
Marking for SG5842ADZ (pb-free)
ZXYTT
SG5842HA
TPM
Marking for SG5842JASY (green-compound)
Marking for SG5842ASY (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 (S=SOP, D=DIP)
P: Y: Green Package
M: Manufacture Flow Code
Figure 3. Top Mark
© 2007 Fairchild Semiconductor Corporation
SG5842A/SG582JA • Rev. 1.4.3
www.fairchildsemi.com
3
SG5842A/SG5842JA — Highly Integrated Green-Mode PWM Controller
Pin Configuration
Figure 4. Pin Configuration
Pin Definitions
Pin #
1
2
Name
GND
FB
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.
For startup, this pin is pulled HIGH to the rectified line input via a resistor. Since the startup
current requirement is very small, a large startup resistance can be used to minimize power loss.
A resistor connected from the RI pin 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.
For over-temperature protection. An external NTC thermistor is connected from 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 output is latched off.
Current sense. The sensed voltage is used for peak-current-mode control and cycle-by-cycle
current limiting.
Power supply. The internal protection circuit disables PWM output if V
DD
is over-voltage.
The totem-pole output driver for the power MOSFET, which is internally clamped below 18V.
3
4
VIN
RI
5
6
7
8
RT
SENSE
VDD
GATE
© 2007 Fairchild Semiconductor Corporation
SG5842A/SG582JA • Rev. 1.4.3
www.fairchildsemi.com
4
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