FAIRCHILD SG6846BCSZ

SG6846B
Highly Integrated Green-Mode PWM Controller
Features
Description
ƒ
ƒ
ƒ
Low Startup Current: 8µA
ƒ
PWM Frequency Continuously Decreasing with
Burst Mode at Light Loads
ƒ
ƒ
ƒ
ƒ
VDD Over Voltage Protection (OVP)
The highly integrated PWM controller, SG6846B,
provides several features to enhance the performance
of fly-back converters. To minimize standby power
consumption, a proprietary green-mode function
provides off-time modulation to continuously decrease
the switching frequency under light-load conditions.
Under zero-load conditions, the power supply enters
burst-mode. This completely shuts off PWM output. If
VFB is larger than around 1.6V, PWM pulses out. This
green-mode function enables power supplies to meet
international power conservation requirements.
ƒ
ƒ
Two-level OCP Delay with 200ms
ƒ
ƒ
OCP Threshold is 2/3 Peak Current Limit
Low Operating Current: 3.7mA
Peak-Current Mode Operation with Cycle-by-cycle
Current Limiting
AC Input Brownout Protection with Hysteresis
Constant Output Power Limit (Full AC Input Range)
Internal Latch Circuit for OVP, OTP, and OCP
(BLSY, BLSZ)
Programmable PWM Frequency with Frequency
Hopping
Soft Startup Time: 5ms
Applications
General-purpose switch-mode power supplies and
flyback power converters, including:
ƒ
ƒ
ƒ
Power Adapters
Open-frame SMPS
SMPS with Surge-current Output, such as for
Printers, Scanners, Motor Drivers
The SG6846B is designed for SMPS with surge-current
output. It is incorporated with a two-level OCP function.
Besides, the cycle-by-cycle current limiting, if the
switching current is higher than OCP threshold and
lasts for 200ms, SG6846B stops gate immediately and
latches itself (BLSY version) or restarts after VDD
charges up to 16.5V (BCSY version). SG6846B also
integrates frequency-hopping function internally. The
frequency hopping function helps reduce EMI emission
of a power supply with minimum line filters. It has builtin synchronized slope compensation, proprietary
internal compensation for constant output power limit
over universal AC input range. The gate output is
clamped at 18V to protect the external MOSFET from
over-voltage damage.
Protection include: AC input brownout protection with
hysteresis and VDD over-voltage protection. For overtemperature protection, an external NTC thermistor can
be applied to sense the ambient temperature. When
OCP, VDD OVP, or OTP are activated, an internal latch
circuit is used to latch-off the controller. The latch resets
when VDD supply is removed.
SG6846B is available in 8-pin SOP package.
Ordering Information
Part
Number
Operating
Temperature Range
OCP
Latch
Eco
Status
Package
Packing
Method
SG6846BLSY
-40 to +105°C
Yes
Green
8-Pin Small Outline Package (SOP)
Tape & Reel
SG6846BLSZ
-40 to +105°C
Yes
RoHS
8-Pin Small Outline Package (SOP)
Tape & Reel
SG6846BCSY
-40 to +105°C
No
Green
8-Pin Small Outline Package (SOP)
Tape & Reel
SG6846BCSZ
-40 to +105°C
No
RoHS
8-Pin Small Outline Package (SOP)
Tape & Reel
For Fairchild’s definition of “green” Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html.
© 2008 Fairchild Semiconductor Corporation
SG6846B • Rev. 1.3.3
www.fairchildsemi.com
SG6846B — Highly Integrated Green-Mode PWM Controller
October 2008
SG6846B — Highly Integrated Green-Mode PWM Controller
Typical Application
L
AC input
EMI
VO+
Filter
+
+
N
VO+
+
7
3
VIN
4
RI
2
FB
VDD
GATE 8
SENSE 6
GND
RT 5
1
SG6846B
Figure 1. Typical Application
Block Diagram
4
0.9V/0.7V
VDD
VIN
3
Soft
Driver
Over Power Compersation
8
GATE
2
FB
6
SENSE
0.895-0.065 XVIN
Q
VDD -TH-G
VDD
UVLO
Green
Mode
OSC
R
Internal
BIAS
7
S
6.2V
3R
+
16.5V/10.5V
1R
Latch
Slope
Compensation
Blanking
Circuit
1R
23.6V
SCP
Delay
IRT
RT
5
2R
Debounce
OTP
Delay
OCP
Delay
1.05V
1.15V
1
GND
Figure 2. Block Diagram
© 2008 Fairchild Semiconductor Corporation
SG6846B • Rev. 1.3.3
www.fairchildsemi.com
2
F: L = OCP Latch, C = OCP auto-recovery
T: S = SOP
P: Z = Lead Free + ROHS Compatible
Null = regular package
XXXXXXXX: Wafer Lot
Y: Year; WW: Week
V: Assembly Location
SG6846BFTP
XXXXXXXXYWWV
※ Marking for SG6846BLSZ (Pb-free)
SG6846BCSZ (Pb-free)
Figure 3. Top Mark 1
SG6846B — Highly Integrated Green-Mode PWM Controller
Marking Information
: Fairchild logo
Z: Plant Code
X: Year Code
Y: Week Code
TT: Die Run Code
F: L = OCP Latch, C = OCP auto-recovery
T: Package type, S = SOP
P: Y = Green Package
M: Manufacturing flow code
※ Marking for SG6846BLSY (Green-compound)
SG6846BCSY (Green-compound)
Figure 4. Top Mark 2
© 2008 Fairchild Semiconductor Corporation
SG6846B • Rev. 1.3.3
www.fairchildsemi.com
3
Figure 5. Pin Configuration
Pin Definitions
Pin #
Name
Function
1
GND
Ground
2
FB
Feedback
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 currentsense signal from pin 6.
3
VIN
Line-voltage
Detection
Line-voltage detection is used for brownout protection with hysteresis. Constant
output power limit over universal AC input range is achieved using this pin. Add
a low-pass filter to filter out line ripple on the bulk capacitor.
4
RI
Reference
Setting
A resistor from the RI pin to ground generates a reference current source that
determines the switching frequency. Increasing the resistance reduces the
switching frequency. A 26kΩ resistor results in a 65kHz switching frequency.
5
RT
Temperature
Detection
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 threshold, PWM
output is disabled.
6
SENSE
Current Sense
The sensed voltage is used for peak-current-mode control and cycle-by-cycle
current limiting. If the switching current is higher than OCP threshold and lasts
for 200ms, SG6846B turns off immediately. This two-level OCP feature is
especially suitable for SMPS with surge current output.
7
VDD
Power Supply
If an open-circuit failure occurs in the feedback loop, the internal protection
circuit disables PWM output as long as VDD exceeds a threshold.
8
GATE
Driver Output
The totem-pole output driver for the power MOSFET; internally clamped
below 18V.
© 2008 Fairchild Semiconductor Corporation
SG6846B • Rev. 1.3.3
Description
Ground.
SG6846B — Highly Integrated Green-Mode PWM Controller
Pin Configuration
www.fairchildsemi.com
4
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. All voltage values, except differential voltages, are
given with respect to GND pin.
Symbol
Parameter
VDD
Supply Voltage
VL
Input Voltage to FB, SENSE, VIN, RT, RI Pins
PD
Power Dissipation at TA<50°C
SOP
Thermal Resistance (Junction-to-Case)
SOP
ΘJC
TJ
TSTG
TL
ESD
Min.
Max.
Unit
30
V
-0.3
7.0
V
400
mW
54.4
°C/W
Operating Junction Temperature
-40
+150
°C
Storage Temperature Range
-65
+150
°C
+260
°C
Lead Temperature, Wave Soldering, 10 Seconds
Human Body Model, JESD22-A114
5.0
Charge Device Model, JESD22-C101
1.5
kV
Recommended Operating Conditions
The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended
operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not
recommend exceeding them or designing to Absolute Maximum Ratings.
Symbol
TA
Parameter
Operating Ambient Temperature
© 2008 Fairchild Semiconductor Corporation
SG6846B • Rev. 1.3.3
Min.
Max.
Unit
-40
+105
°C
SG6846B — Highly Integrated Green-Mode PWM Controller
Absolute Maximum Ratings
www.fairchildsemi.com
5
VDD = 15V and TA = 25°C unless otherwise noted.
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
Unit
20
V
VDD Section
VDD-OP
Continuously Operating Voltage
VDD-ON
Turn-on Threshold Voltage
15.5
16.5
17.5
V
VDD-OFF
Turn-off Voltage
9.5
10.5
11.5
V
VDD-SCP
Threshold Voltage on VDD for Short-Circuit
Protection
VDD-LH
Threshold Voltage for Latch-off Release
IDD-ST
Startup Current
VDD-ON – 0.16V
IDD-OP
Operating Supply Current
GATE Open
VDD-OFF VDD-OFF VDD-OFF
+0.5V +1.0V +1.5V
3
VDD-OVP
VDD Over-Voltage Protection (Latch off)
tD-VDDOVP
VDD OVP Debounce Time
RI = 26kΩ
VDD OVP Latch-off Holding Current
VDD = 5V
IDD-OVP
23
V
4
5
V
8
30
µA
3.7
5.0
mA
24
25
V
150
µs
30
50
70
µA
VIN Section
VIN-OFF
PWM Turn-off Threshold Voltage
0.65
0.70
0.75
V
VIN-ON
PWM Turn-on Threshold Voltage
VIN-OFF
+0.18
VIN-OFF
+0.20
VIN-OFF
+0.22
V
1/3.5
1/4.0
1/4.5
V/V
Feedback Input Section
AV
Input-Voltage to Current-Sense Attenuation
ZFB
Input Impedance
4.0
5.5
7.0
kΩ
VFBO
FB Pin Open Voltage
5.2
6.2
6.6
V
SG6846B — Highly Integrated Green-Mode PWM Controller
Electrical Characteristics
Current Sense Section
ZSENSE
Input Impedance
12
tPD
Delay to Output
100
tLEB
Leading-edge Blanking Time
270
360
kΩ
250
ns
ns
VSLOPE
Slope Compensation
Duty = DCYMAX
0.30
0.33
0.36
V
VSTH1V
Threshold Voltage for Current Limit
VIN = 1V
0.80
0.83
0.86
V
VSTH3V
Threshold Voltage for Current Limit
VIN = 3V
0.67
0.70
0.73
V
VSTH1V-2/3
OCP Threshold Voltage for Current Limit
VIN = 1V
0.58
0.61
0.64
V
VSTH3V-2/3
OCP Threshold Voltage for Current Limit
VIN = 3V
0.48
0.51
0.54
V
tD-OCP
Delay Time for Over-Current Protection
RI = 26kΩ
175
200
225
ms
tD-Short
Output Short Circuit Protection delay time
VCS > VSTH, RI = 26kΩ,
VDD < VDD-SCP
6
7
8
ms
RI = 26kΩ
4.5
5.0
5.5
ms
RI = 13kΩ
2.25
2.50
2.75
ms
tSS-65KHz
tSS-130KHz
Period During Soft Start Time
Continued on following page…
© 2008 Fairchild Semiconductor Corporation
SG6846B • Rev. 1.3.3
www.fairchildsemi.com
6
YES
NO
NO
(2 )
IP > 2 / 3 IPK ?
(5 )
Timing = 200ms
YES
NO
(6 )
VDD < = 12 V ?
SCP
(3 )
Timing = 8 ms
OCP
(7 ) Gate-off
SCP
Figure 6. SG6846B OCP/SCP Logic Flow Diagram
Electrical Characteristics (Continued)
VDD = 15V and TA = 25°C unless otherwise noted.
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
62
65
68
±3.7
±4.2
±4.7
124
130
136
±7.4
±8.4
±9.4
44.8
47.0
49.2
±2.54
±2.90
±3.26
Unit
Oscillator Section
fOSC
Normal PWM Frequency
Center
Frequency
RI = 26kΩ, VFB>VN
Jitter Range
fOSC,MAX
fOSC,MIN
Maximum PWM
Frequency
Center
Frequency
RI = 13kΩ, VFB>VN
Jitter Range
Center
Minimum PWM Frequency Frequency
RI = 36kΩ, VFB>VN
Jitter Range
kHz
kHz
kHz
thop-1
Jitter Period
RI = 26kΩ, VFB ≥ VN
3.9
4.4
4.9
ms
thop-3
Jitter period
RI = 26kΩ, VFB = VG
10.2
11.5
12.8
ms
fOSC-G
Green-Mode Minimum Frequency
RI = 26kΩ
18.0
22.5
25.0
kHz
SG
Slope for Green-Mode Modulation
RI = 26kΩ
VFB-N
Pin, FB voltage
FB Pin Frequency
Reduction Threshold Jitter Range
RI = 26kΩ, VFB = VN
VFB-G
FB Voltage at fOSC-G
Pin, FB voltage
RI = 26kΩ, VFB = VG
Jitter Range
fDV
Frequency Variation vs. VDD Deviation
VDD = 11.5V to 20V
fDT
Frequency Variation vs. Temperature
Deviation
TA = -30 to 85°C
85
Hz/mV
1.9
2.1
2.3
V
3.7
4.2
4.7
KHz
1.4
1.6
1.8
V
1.27
1.45
1.62
KHz
5
%
5.0
%
1.5
SG6846B — Highly Integrated Green-Mode PWM Controller
(4 )
VDD < 12 V ?
( 1 ) normal
operation
Continued on following page…
© 2008 Fairchild Semiconductor Corporation
SG6846B • Rev. 1.3.3
www.fairchildsemi.com
7
Electrical Characteristics (Continued)
VDD = 15V and TA = 25°C unless otherwise noted.
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
Unit
80
85
90
%
1.5
V
PWM Output Section
DCYMAX
Maximum Duty Cycle
VOL
Output Voltage Low
VDD = 15V, IO = 50mA
VOH
Output Voltage High
VDD = 12V, IO = 50mA
tR
Rising Time
GATE = 1nF
350
ns
tF
Falling Time
GATE = 1nF
50
ns
VCLAMP
Gate Output Clamping Voltage
8
SG6846B — Highly Integrated Green-Mode PWM Controller
Figure 7. PWM Frequency
V
VDD = 20V
18
V
(1)
Over-Temperature Protection (OTP) Section
IRT
VRTTH
tDOTP-LATCH
RRT-OFF
Output Current of RT Pin
RI = 26kΩ
Threshold Voltage for OTP
Over-Temperature Latch-off Debounce
RI = 26kΩ
(1)
RI = 26kΩ
Equivalent Impedance of RT for OTP
64
70
76
µA
1.00
1.05
1.10
V
100
14
15
ms
16
kΩ
36
kΩ
RI Section
RINOR
RI Operating Range
13
RIMAX
Maximum RI Value for Protection
10
RIMIN
Minimum RI Value for Protection
MΩ
6
Note:
1. The relationship between RRT-OFF and RI is: RRT -OFF = VOTP-LATCH-OFF / IRT = VRT / (70 μA × 26 / RI (KΩ ))
© 2008 Fairchild Semiconductor Corporation
SG6846B • Rev. 1.3.3
kΩ
(1)
www.fairchildsemi.com
8
Turn-off Voltage (V DD-OFF) vs Temperature
1 1 .5
1 6 .8
1 1 .0
1 6 .6
V DD-OFF (V)
V DD-ON (V)
Turn-on Threshold Voltage (V DD-ON ) vs Temperature
1 7 .0
1 6 .4
1 0 .5
1 0 .0
1 6 .2
9 .5
1 6 .0
9 .0
-4 0
-2 5
-1 0
5
20
35
50
65
80
95
110
125
-4 0
-2 5
-1 0
5
Temperature (℃ )
DD -ST
65
80
95
110
125
Operating Supply Current (IDD-op) vs Temperature
) vs Temperature
6 .0
22.0
5 .5
IDD-op (mA)
IDD -ST (µA)
50
Figure 9. Turn-off Threshold Voltage (VDD-OFF)
vs. Temperature
26.0
18.0
14.0
5 .0
4 .5
10.0
6.0
4 .0
-40
-25
-10
5
20
35
50
65
80
95
110
125
-4 0
Temperature (℃)
0.66
-2 5
-1 0
5
20
35
50
65
80
95
110
125
Temperature (℃ )
Figure 10. Startup Current (IDD-ST) vs. Temperature
Figure 11. Operating Supply Current (IDD-op) vs.
Temperature
OCP ThresholdVoltage for Current Limit (VSTH3V-2/3) vs
Temperature
OCP Threshold Voltage for Current Limit (VSTH1V-2/3) vs
Temperature
0.60
0.64
0.58
0.62
0.56
VSTH3V-2/3 (V)
VSTH1V-2/3 (V)
35
Temperature (℃ )
Figure 8. Turn-on Threshold Voltage (VDD-ON)
vs. Temperature
Startup Current (I
20
SG6846B — Highly Integrated Green-Mode PWM Controller
Typical Performance Characteristics
0.60
0.58
0.54
0.52
0.56
0.50
-40
-25
-10
5
20
35
50
65
80
95
110
125
-40
Figure 12. OCP Threshold Voltage for Current Limit
(VSTH1V-2/3) vs. Temperature
© 2008 Fairchild Semiconductor Corporation
SG6846B • Rev. 1.3.3
-25
-10
5
20
35
50
65
80
95
110
125
Temperature (℃)
Temperature (℃ )
Figure 13. OCP Threshold Voltage for Current Limit
(VSTH3V-2/3) vs. Temperature
www.fairchildsemi.com
9
Maximum Duty Cycle (DCYmax) vs Temperature
Normal PWM Frequency (f OSC ) vs Temperature
8 7.2
64.0
8 7.0
DCYmax (%)
f OSC (kHz)
63.5
63.0
62.5
8 6.8
8 6.6
8 6.4
62.0
-40
-25
-10
5
20
35
50
65
80
95
110
8 6.2
125
-4 0
Temperature (℃ )
-2 5
5
20
50
65
80
95
110
12 5
Figure 15. Maximum Duty Cycle (DCYmax)
vs. Temperature
Output Current of RT Pin (IR T ) vs Temperature
Trigger Voltage of OTP (VR TT H ) vs Temperature
1.10
70.6
1.08
70.4
1.06
VR TT H (V)
70.8
70.2
70.0
1.04
1.02
69.8
1.00
-40
-25
-10
5
20
35
50
65
80
95
110
125
-40
-25
-10
5
20
Temperature (℃)
35
50
65
80
95
110
125
Temperature (℃)
Figure 16. Output Current of RT pin (IRT)
vs. Temperature
Figure 17. Trigger Voltage of OTP(VRTTH)
vs. Temperature
PW M Turn-off Threshold Voltage (V IN-OFF ) vs Temperature
PW M Turn-on Threshold Voltage (V IN-ON ) vs Temperature
0 .7 1 5
0.925
0 .7 1 0
V IN-OFF (V)
0.920
V IN-ON (V)
35
Temperature (℃ )
Figure 14. Normal PWM Frequency (fOSC)
vs. Temperature
IR T (µA)
-10
SG6846B — Highly Integrated Green-Mode PWM Controller
Typical Performance Characteristics (Continued)
0.915
0 .7 0 5
0 .7 0 0
0.910
0 .6 9 5
0.905
0 .6 9 0
-40
-25
-10
5
20
35
50
65
80
95
1 10
125
-4 0
Figure 18. PWM Turn-on Threshold Voltage (VIN-ON)
vs. Temperature
© 2008 Fairchild Semiconductor Corporation
SG6846B • Rev. 1.3.3
-2 5
-1 0
5
20
35
50
65
80
95
110
125
Temperature (℃ )
Temperature (℃ )
Figure 19. PWM Turn-off Threshold Voltage (VIN-OFF)
vs. Temperature
www.fairchildsemi.com
10
Startup Operation
fPWM(kHz) =
The turn-on/turn-off thresholds are fixed internally at
16.5V and 10.5V. To enable the SG6846B during
startup, the hold-up capacitor must first be charged to
16.5V through the startup resistor.
If an open-circuit or short-circuit to ground occurs at the
RI pin, the internal protection circuit immediately shuts
down the controller.
If an open-circuit or short-circuit to ground occurs at the
RI pin, the internal protection circuit immediately shuts
down the controller.
Two-level Over-current Protection (OCP)
The cycle-by-cycle current limiting shuts down the PWM
immediately when the switching current is over the
peak-current threshold. Additionally, when the switching
current is higher than over-current threshold, the internal
counter counts down. When the total accumulated
counting time is more than ~200ms (RI = 26kΩ), the
controller is latched off and the internal counter counts
up. When the switching current is lower than overcurrent threshold, the internal counter counts down.
When the total accumulated counting time is more than
~200ms (RI = 26kΩ), the controller is latched off.
The hold-up capacitor continues to supply VDD before
energy can be delivered from the auxiliary winding of
the main transformer. The VDD must not drop below
10.5V during this startup process. This UVLO hysteresis
window ensures that the hold-up capacitor can
adequately supply VDD during startup.
The typical startup current is only 8µA, which allows a
high-resistance, low-wattage startup resistor to be used.
For constant output power limit over a universal inputvoltage range, the peak-current threshold is adjusted by
the voltage of the VIN pin. Since the VIN pin is
connected to the rectified AC input line voltage through
the resistive divider, a higher line voltage generates a
higher VIN voltage. The threshold voltage decreases as
the VIN increases, making the maximum output power at
high line input voltage equal to that at low line input.
The value of R-C network should not be so large it
affects the power limit (shown in Figure 20). R and C
should put on less than 300Ω and 1000pF, respectively,
to minimize power loss. A 1.5MΩ/0.25W startup resistor
and a 10µF/25V VDD hold-up capacitor are sufficient for
a universal input range.
This two-level OCP protection and up/down counter are
especially designed for SMPS with surge current output,
such as those for printers, scanners, and motor drivers.
Constant Output Power Limit
For constant output power limit over universal inputvoltage range, the peak-current threshold is adjusted by
the voltage of the VIN pin. Since the VIN pin is
connected to the rectified AC input line voltage through
the resistive divider, a higher line voltage generates a
higher VIN voltage. The threshold voltage decreases as
VIN increases, making the maximum output power at
high-line input voltage equal to that at low-line input.
The required operating current has been reduced to
3.7mA, which enables higher efficiency and reduces the
VDD hold-up capacitance requirement.
Brownout Protection
Since the VIN pin is connected through a resistive
divider to the rectified AC input line voltage, it can also
be used for brownout protection. If the VIN voltage is
less than 0.7V, the PWM output is shut off. If the VIN is
over 0.9V, the PWM output is turned on again. The
hysteresis window for on/off is ~0.2V.
Green-Mode Operation
The proprietary green-mode function provides off-time
modulation to continuously decrease the switching
frequency under light-load conditions. Maximum on-time
is limited to provide protection against abnormal
conditions. To further reduce power consumption under
zero-load condition, the PWM oscillator is completely
turned off and the power supply enters burst-mode.
Green mode dramatically reduces power consumption
under light-load and zero-load conditions. Power
supplies using SG6846B can meet restrictive
international regulations regarding standby power
consumption.
VDD Over-voltage Protection (OVP)
VDD over-voltage protection is built in to prevent
damage. If VDD is over 24V, SG6846B is latched off.
Over-Temperature Protection (OTP)
An external NTC thermistor can be connected from the
RT pin to GND. The impedance of the NTC decreases
at high temperatures. When the voltage of the RT pin
drops below 1.05V, the SG6846B is turned off. For
protection-mode options, see Ordering Information.
Oscillator Operation
A resistor connected from the RI pin to GND generates
a internal reference current source used to determine
the PWM frequency. Increasing the resistance
decreases the amplitude of the current source and
reduces the PWM frequency. Using a 26kΩ resistor
results in a corresponding 65kHz switching frequency.
The relationship between RI and the switching
frequency is:
© 2008 Fairchild Semiconductor Corporation
SG6846B • Rev. 1.3.3
(2)
1690
R I (kΩ )
SG6846B — Highly Integrated Green-Mode PWM Controller
Operation Description
www.fairchildsemi.com
11
Noise Immunity
Noise from the current sense or the control signal may
cause significant pulse-width jitter, particularly in
continuous-conduction mode. Slope compensation
helps alleviate this problem. Good placement and
layout practices should be followed. Avoid long PCB
traces and component leads. Compensation and filter
components should be located near the SG6846B.
Figure 20. Current Sense R-C Filter
© 2008 Fairchild Semiconductor Corporation
SG6846B • Rev. 1.3.3
SG6846B — Highly Integrated Green-Mode PWM Controller
Operation Description (Continued)
www.fairchildsemi.com
12
RT1
R16
D4
2
4
1
5
2
32V
C13
11
C11
12
2
P16V
P16V L2
1
2
2
R11
C5
3
C17+
C14
+
16V 16V
C15
+
1
1
C3
2
R17
2
+
1
9
3
2
+
32V
+
2
1
21
2
1
R4
7
1
1
2
D3
L4
C12
+
10
D2
D1
2
2
6
R9
R3
C16+
3
R12 C4
C2
3
2
R2
R1
13
1
+
R8
1
P7
P32V
P32V L1
1
2
CX2
4
3
1
P2
TX1
1
VZ1
LF1 CY2
BD1
1
CX1LF2
3
4
2
CY1
1
F1
t
P1
2
U1
FB
GATE
Q1
R13
8
1
2
GND
3
1
2
FB
VDD
VIN
SENSE
7
L3
R6
6
1
2
3
1
D5
+
1
C1
R5
4
RI
RT
5
R10
C6
R14
NTC1
R7
P16V
P16V
1
4
R15
FB
P16V
FB
C7
K
R18
P32V
R19
R20
2
3
U2
P32V
P16V
C9
R
R21
A
U3
Figure 21. Application Circuit for 32V / 16V Output
SG6846B — Highly Integrated Green-Mode PWM Controller
Reference Circuit
BOM
Part No.
Value
Part No.
Value
Part No.
Value
R1, R2, R3, R4
R8, R9
470KΩ +/-5%
C4
S1MΩ +/-1%
C10,C11
103P 630V
D3
FR103 1.0A 200V
102P 1KV
BD1
DBL406G
R5
16K2Ω +/-1%
C6,C7
102P 50V
D4
BYT28-300
R15
R13
1K5Ω +/-5%
C9
222P 50V
D5
BYV32-150
10Ω +/-5%
C14,C17
470µ 25V
F1
250V4A QUICK
R18
4K7Ω +/-5%
C15
220µ 25V
L1,L2
1.8µH
R21
15KΩ +/-1%
C13,C16
220µ 50V
L4
10µH
R7
27KΩ +/-5%
C2
150µ 400V
U3
TL431 +/-1%
R6
330Ω +/-1%
C1
4.7µ 50V
U1
SG 6846
R19
102KΩ +/-1%
C3
10µ 50V
U2
PC817
R14
0Ω22 +/-5%
CX1
X1 0.47µ 275V
Q1
7NB60
R16, R17
1W 20Ω +/-5%
C8
Y2 222P 250V
TX1
EI-33
R11
20KΩ +/-5%
C5
100µ 50V
RT1
SCK053
R12
100KΩ +/-5%
CX2
X2 0.1µF 275V
VZ1
14ψ 470V
R20
887KΩ +/-1%
D1
1N4148
R22
10KΩ +/-1%
D2
BYV95C
© 2008 Fairchild Semiconductor Corporation
SG6846B • Rev. 1.3.3
www.fairchildsemi.com
13
5.00
4.80
A
0.65
3.81
5
8
B
6.20
5.80
PIN ONE
INDICATOR
1.75
4.00
3.80
1
5.60
4
1.27
(0.33)
0.25
M
1.27
C B A
LAND PATTERN RECOMMENDATION
0.25
0.10
SEE DETAIL A
1.75 MAX
R0.10
0.10
0.51
0.33
0.50 x 45°
0.25
C
OPTION A - BEVEL EDGE
GAGE PLANE
R0.10
8°
0°
0.90
0.406
0.25
0.19
C
SG6846B — Highly Integrated Green-Mode PWM Controller
Physical Dimensions
OPTION B - NO BEVEL EDGE
0.36
NOTES: UNLESS OTHERWISE SPECIFIED
A) THIS PACKAGE CONFORMS TO JEDEC
MS-012, VARIATION AA, ISSUE C,
B) ALL DIMENSIONS ARE IN MILLIMETERS.
C) DIMENSIONS DO NOT INCLUDE MOLD
FLASH OR BURRS.
D) LANDPATTERN STANDARD: SOIC127P600X175-8M.
E) DRAWING FILENAME: M08AREV13
SEATING PLANE
(1.04)
DETAIL A
SCALE: 2:1
Figure 22. 8-Pin Small Outline Package (SOP)
Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner
without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify
or obtain the most recent revision. Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically
the warranty therein, which covers Fairchild products.
Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings:
http://www.fairchildsemi.com/packaging/.
© 2008 Fairchild Semiconductor Corporation
SG6846B • Rev. 1.3.3
www.fairchildsemi.com
14
SG6846B — Highly Integrated Green-Mode PWM Controller
© 2008 Fairchild Semiconductor Corporation
SG6846B • Rev. 1.3.3
www.fairchildsemi.com
15