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PDF SG6846A Data sheet ( Hoja de datos )
| Número de pieza | SG6846A | |
| Descripción | Highly-Integrated Green-Mode PWM Controller | |
| Fabricantes | ETC | |
| Logotipo |  |
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Highly Integrated Green-Mode PWM Controller
FEATURES
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Two-level OCP with 1700ms delay time
Output short-circuited delay time: 100ms
Low start-up current (8µA)
Low operating current (3.7mA)
Peak-current mode operation with cycle-by-cycle
current limiting
Programmable PWM frequency with frequency
hopping
PWM frequency continuously decreasing with burst
mode at light loads
VDD over-voltage protection (OVP)
AC input brownout protection with hysteresis and
constant output power limit
Constant output power limit (full AC input range)
Internal latch circuit for OVP, OTP, and OCP
Built-in soft-start
Open-loop protection with 1700ms delay time
APPLICATIONS
General-purpose switch-mode power supplies and
flyback power converters, including:
Power adapters
Open-frame SMPS
Specifically fit for SMPS with surge-current output
(such as for printers, scanners, motor drivers, etc.)
DESCRIPTION
The highly integrated SG6846A series of PWM
controllers provides features to enhance the performance
of flyback converters. To minimize standby power
Product Specification
SG6846A
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.
The SG6846A is especially designed for SMPS with
surge-current output, incorporated with a two-level OCP
function. Besides the cycle-by-cycle current limiting, if
the switching current is higher than two thirds the
peak-current threshold for 1700ms, over-current
protection is activated and the SG6846A latches off.
If the switching current is higher than two thirds the
peak-current threshold for 100ms and the voltage on the
VDD pin is higher than VDD-OFF + 1V, the PWM pulses
are latched off immediately once VDD voltage is lower
than VDD-OFF + 1V; useful if an output short-circuit occurs.
SG6846A also integrates a frequency hopping function
that reduces EMI emission of a power supply with
minimum line filters. Its built-in synchronized slope
compensation provides proprietary internal compensation
for constant output power limit over a universal AC input
range. Also, the gate output is clamped at 18V to protect
the external MOSFET from over-voltage damage.
Internal soft-start is built-in to reduce stress on the
MOSFET and start-up current during power-on period.
Other protection functions include: AC input brownout
protection with hysteresis, VDD over-voltage protection,
and over-temperature protection. For over-temperature
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 PWM pulses stay latched off
until the power supply is unplugged from the main outlet.
SG6846A is available in an 8-pin SOP package.
TYPICAL APPLICATION
© System General Corp.
Version 1.1.1 (IAO33.0059.B1)
- 1 - www.sg.com.tw • www.fairchildsemi.com
September 26, 2007
1 page  
Highly Integrated Green-Mode PWM Controller
FEEDBACK INPUT SECTION
Symbol
AV
ZFB
VFB-OPEN
VFB-OLP
tD-OLP
Parameter
Input Voltage to Current-Sense Attenuation
Input Impedance
FB Pin Open Voltage
FB Open-Loop Trigger Level
Delay Time of FB Pin Open-Loop Protection
Product Specification
SG6846A
Test Condition
At Green Mode
Min.
RI=26KΩ
5.6
4.7
1600
Typ.
1/4
5.5
6.2
5.2
1700
Max.
6.6
5.7
1800
Unit
V/V
kΩ
V
V
ms
CURRENT-SENSE SECTION
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Symbol Parameter
ZSENSE
tPD
tLEB
VSTH1V
VSTH3V
VSTH1V-2/3
VSTH3V-2/3
tD-OCP
VSLOPE
tD-Short
tSS-65KHz
tSS-130KHz
Input Impedance
Delay to Output
Leading-Edge Blanking Time
Threshold Voltage for Current Limit
Threshold Voltage for Current Limit
2/3 Threshold Voltage for Current Limit
2/3 Threshold Voltage for Current Limit
*Delay Time for Over-Current Protection
Slope Compensation
*Output Short Delay Time
Soft-Start Time
Soft-Start Time
Test Condition Min.
VIN=1V
VIN=3V
VIN=1V
VIN=3V
RI=26KΩ
Duty=DCYMAX
VCS> VSTH, RI=26KΩ
RI=26KΩ
RI=13KΩ
270
0.58
0.48
1500
92
Typ.
12
360
0.83
0.70
0.61
0.51
1600
0.33
100
5
2.5
Max.
250
0.64
0.54
1700
108
Unit
kΩ
ns
ns
V
V
V
V
ms
V
ms
ms
ms
OSCILLATOR SECTION
Symbol
FOSC
FOSC,MAX
FOSC,MIN
thop-1
FOSC-G
VFB-N
VFB-G
SG
FDV
FDT
Parameter
Normal PWM Frequency
Center Frequency
Jitter Range
Maximum PWM Frequency
Center Frequency
Jitter Range
Minimum PWM Frequency
Center Frequency
Jitter Range
Jitter Period
Green-Mode Minimum Frequency
FB Pin Frequency Reduction
Pin, FB Voltage
Threshold
Jitter Range
FB Voltage at FOSC-GREEN
Pin, FB Voltage
Jitter Range
Slope for Green-Mode Modulation
Frequency Variation vs. VDD Deviation
Frequency Variation vs. Temperature Deviation
Test Condition
RI=26KΩ, VFB>VN
RI=13KΩ, VFB>VN
RI=36KΩ, VFB>VN
RI=26KΩ, VFB>VN
RI=26KΩ
RI=26KΩ, VFB=VN
RI=26KΩ, VFB=VG
RI=26KΩ
VDD=11.5V to 20V
TA=-20 to 85 °C
Min.
62
124
44.8
18.0
Typ.
65
±4.2
130
±8.4
47.0
±2.9
4.4
22.5
2.1
4.2
1.6
1.45
85
1.5
Max.
68
136
49.2
25.0
5
5.0
Unit
kHz
kHz
kHz
ms
kHz
V
KHz
V
KHz
Hz/mV
%
%
© System General Corp.
Version 1.1.1 (IAO33.0059.B1)
- 5 - www.sg.com.tw • www.fairchildsemi.com
September 26, 2007
5 Page 
Highly Integrated Green-Mode PWM Controller
Product Specification
SG6846A
REFERENCE CIRCUIT
Application Circuit for 32V/16V Output
P1 F1
P2
P7
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RT1
CY1
VZ1
LF1 CY2
CX1LF2
CX2 4
R1 R2
R3
R4
BD1
1
R8
+
C2
R12 C4
D2
12
R9
D1
1
L4 D3
2 1 12 2
+
C3
+
C5
R11
TX1
5 13
6
10
79
1
3 11
D4R16 P32V
L11
P32V
2
3 C16+ +C12
C11 R17
1
3
D5
P16V
L2P16V
2
C17+ +C14
32V 32V
+C13
16V 16V
+C15
C1 +
U1
1 GND
FB 2 FB
3
R5 4
R7
VIN
RI
GATE
8
VDD
7
SENSE
6
RT 5 R10
R13 1
C6
NTC1
R6
Q1
L3
R14
P16V
P16V
FB
FB
C7
R15
P16V
P32V
C9 P16V
P32V
R18 R19 R20
U2
R
U3 R21
BOM
PART NO.
R1, R2, R3, R4
R8, R9
R5
R15
R13
R18
R21
R7
R6
R19
R14
R16, R17
R11
R12
R20
R22
VALUE
470KΩ +/-5%
S1MΩ +/-1%
16K2Ω +/-1%
1K5Ω +/-5%
10Ω +/-5%
4K7Ω +/-5%
15KΩ +/-1%
27KΩ +/-5%
330Ω +/-1%
102KΩ +/-1%
0Ω22 +/-5%
1W 20Ω +/-5%
20KΩ +/-5%
100KΩ +/-5%
887KΩ +/-1%
10KΩ +/-1%
PART NO.
C4
C10,C11
C6,C7
C9
C14,C17
C15
C13,C16
C2
C1
C3
CX1
C8
C5
CX2
D1
D2
VALUE
103 P 630V
102 P 1KV
102 P 50V
222 P 50V
470µ 25V
220µ 25V
220µ 50V
150µ 400V
4µ7 50V
10µ 50V
X1 0.47µ 275V
Y2 222P 250V
100µ 50V
X2 0.1µF 275V
1N4148
BYV95C
PART NO.
D3
BD1
D4
D5
F1
L1,L2
L4
U3
U1
U2
Q1
TX1
RT1
VZ1
VALUE
FR103 1.0A 200V
DBL406G
BYT28-300
BYV32-150
250V4A QUICK
1.8µH
10µH
TL431 +/-1%
SG 6846
PC817
7NB60
EI-33
SCK053
14ψ 470V
© System General Corp.
Version 1.1.1 (IAO33.0059.B1)
- 11 -
www.sg.com.tw • www.fairchildsemi.com
September 26, 2007
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet SG6846A.PDF ] | |
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