Product Specification
BiCMOS Green-Mode PWM Controllers
SG3842G/ SG3843G
FEATURES
384x series pin-to-pin compatible
Linearly decreasing PWM frequency
Burst-mode at low/zero load
5uA start-up current
5mA operating current
Vcc over voltage protection
Cycle-by-cycle current limiting
Zero cross-conduction
Slew rate controlled high current totem pole output
Fast current sense propagation delay
Under voltage lockout (UVLO) with hysteresis
start-up current has been reduced to 5uA, and the
minimum operating current has been reduced to 5mA.
Each SG384xG has a slew rate controlled high current
totem pole output, ideally suited for driving a power
MOSFET while keeping EMI low.
The current-sense propagation delay is typically
50ns, resulting in significantly more effective constant
power protection. During normal operation, a SG384xG
controller acts as a fixed frequency PWM controller. The
PWM frequency can be easily programmed by changing
external R
T
and C
T
values. The SG384xG includes two
Green-mode functions that dramatically reduce power
usage, helping the power supply comply with the latest
international power saving guidelines. To cut power
consumption under light load conditions, the controller’s
Green-mode function will linearly decrease the PWM
frequency in response to decreases in the output load.
Under ultra light-load/zero-load conditions, the RT/CT
PWM oscillator periodically shuts down, and enters into
Burst-mode. This causes the IC’s supply voltage to begin
gradually dropping. Just before the supply voltage drops
below the UVLO voltage threshold, the RT/CT PWM
oscillator turns back on, to prevent the supply voltage
from going below the UVLO voltage.
SG384xG controllers also come with Over Voltage
Protection (OVP). This shuts down PWM output if the
supply voltage ever exceeds 27V. The SG384xG series
comes in 8-pin DIP and SOP
packages.
APPLICATIONS
Switching mode power supplies
Power converters
DESCRIPTION
The SG348xG series of current-mode PWM
controllers combines high performance with Green-mode
power saving features. SG348xG controllers are fully
pin-to-pin compatible with bipolar UC384x devices, but
they have improved features and functionality. SG384xG
series controllers are compatible with the BiCMOS
fabrication process, enabling the use of low start-up
current and operating currents. This feature further
improves power conversion efficiency. The minimal
TYPICAL APPLICATION
Green-mode Operation
Oscillator Frequency vs. COMP
From bridge rectifier
120~ 380VDC
From auxiliary winding
R
IN
1.5M
VCC
Rac
10k
R
T
10k
C
T
3.3n
C21
0.1u
COMP
OUTPUT
VREF
C
IN
10u
60
50
Oscillator Frequency (Fosc) vs COMP Voltage
R41
100
Fosc (kHz)
40
30
20
10
0
1
1.5
2
COMP VOLTAGE (V)
2.5
3
SG384x
RT/CT
VFB
GND
SENSE
R42
1k
C25
100p
R
S
0.3
© System General Corp.
Version 1.4 ( IRO33.0007.B3)
-1-
www.sg.com.tw
Jun.28,2004
Product Specification
BiCMOS Green-Mode PWM Controllers
SG3842G/ SG3843G
MARKING INFORMATION
8
Z:
2, 3
PIN CONFIGURATION
SG384ZGTP
AXXXXXXXYYWWV
T:
D = DIP, S = SOP
P :
Z = Lead Free
Null=Regular Package
XXXXXXX:
Wafer Lot
YY:
Year;
WW:
Week
V:
Assembly Location
COMP
VFB
SENSE
RT/CT
1
2
3
4
8
7
6
5
VREF
VCC
OUTPUT
GND
1
ORDERING INFORMATION
Part Number
SG3842GAD
SG3842GAS
SG3842G2AD
SG3842G2AS
SG3843GAD
SG3843GAS
SG3842GADZ
SG3842GASZ
SG3842G2ADZ
SG3842G2ASZ
SG3843GADZ
SG3843GASZ
8.9V±0.5V
8.1V±0.5V
16V±1V
10V±1V
3.0
3.0
8.9V±0.5V
8.1V±0.5V
16V±1V
10V±1V
3.0
3.0
5.0
UVLO
Start threshold
Stop threshold
AV
5.0
8-Pin DIP
Package
8-Pin SOP
8-Pin DIP
8-Pin SOP
8-Pin DIP
8-Pin SOP
8-Pin DIP(Lead Free)
8-Pin SOP( Lead Free)
8-Pin DIP(Lead Free)
8-Pin SOP( Lead Free)
8-Pin DIP( Lead Free)
8-Pin SOP( Lead Free)
PIN DESCRIPTIONS
Pin No.
1
2
3
4
5
6
7
8
Symbol
COMP
VFB
SENSE
RT/CT
GND
OUTPUT
VCC
VREF
Function
Compensation
Feedback
Current sense
Oscillator control
Ground
Output
Power supply
Reference voltage
Description
Output of the Error Amplifier and input to the PWM comparator. It is used for feedback
loop compensation.
Inverting input of the Error Amplifier. It is normally connected to the switching power
supply output through a resistor divider.
Current sense comparator input. It is internally set to 1V maximum. A voltage proportional
to the inductor current is connected to this input.
Oscillator RC timing connection. Connecting a resistor RT from this pin to Vref, and a
capacitor CT from this pin to ground, programs the oscillator frequency and the maximum
output duty cycle.
This pin is the combined control circuit ground and power ground.
High-power, totem-pole driver output. This output drives the gate of a power MOSFET.
Supply voltage input.
5V-reference voltage output.
© System General Corp.
Version 1.4 ( IRO33.0007.B3)
-2-
www.sg.com.tw
Jun.28,2004
Product Specification
BiCMOS Green-Mode PWM Controllers
SG3842G/ SG3843G
BLOCK DIAGRAM
ABSOLUTE MAXIMUM RATINGS
Symbol
Vcc
Iz
V
IN
I
SINK
Pd
R
Θ
j-a
T
J
T
a
Tstg
T
L
Supply voltage
Zener current
FB/SENSE terminal input voltage
Error amplifier sink current
Power dissipation
Thermal resistance
Operating junction temperature
Operating ambient temperature
Storage temperature range
Lead temperature (Soldering)
ESD Capability, HBM model
ESD Capability, Machine model
Parameter
Test Condition
Low impedance source
Zener clamp
FB, SENSE
at Ta<50°C
Junction-air
-
-
-
10 sec
20 sec
DIP
SOP
DIP
SOP
Value
25
28
10
-0.3 to 5.5V
10
800
400
82.5
141
+150
-40 to 125
-65 to +150
260
220
3.0
200
V
Unit
mA
V
mA
mW
°C/W
°C
°C
°C
°C
kV
V
DIP
SOP
© System General Corp.
Version 1.4 ( IRO33.0007.B3)
-3-
www.sg.com.tw
Jun.28,2004
Product Specification
BiCMOS Green-Mode PWM Controllers
SG3842G/ SG3843G
OPERATING CONDITIONS
Symbol
Vcc
C
T
R
T
f
OSC
T
a
Parameter
Supply voltage
Oscillation timing capacitor
Oscillation timing resistor
Oscillation frequency
Operating ambient temperature
-
0.47
2.0
10
-40
Min.
20
10
100
500
105
Max.
Unit
V
nF
kΩ
kHz
°C
ELECTRICAL CHARACTERISTICS
Reference Voltage Section
Symbol
Vref
Line
Load
Vtc
Ios
Vref
Vn
S
Parameter
Reference output voltage
Line regulation
Load current regulation
Temperature stability
Short-circuit output current
Total output variation
Output noise voltage
Long term stability
Test Condition
Ta=25°C, Io=1mA
Vcc=10 to 20V
Io=1mA to 20mA
-
-
Line, Load, Temperature
f=10Hz to 10kHz , Ta=25°C
Ta=125°C for 1000 hours
Min.
4.75
-
-
-
-30
4.75
-
-
Typ.
5.0
2
20
0.5
-85
5.0
50
5
Max.
5.25
20
50
-
-180
5.25
-
25
Unit
V
mV
mV
mV/°C
mA
V
uV
mV
Oscillator Section
(VFB=0V, SENSE=0V)
Symbol
F
OSC
F
OSC-G
V
comp,H
V
comp,L
fdv
fdt
I
DISCHG
Parameter
Oscillator frequency
Green-mode frequency (note 1)
Comp Voltage that initiates Green-mode
Comp Voltage that shuts down PWM
Frequency change with Vcc
Frequency change with temp.
Discharge current
Test Condition
SG3842G, SG3843G
SG3842G2
Vsense=0V
SG3842G
SG3842G2, SG3843G
SG3842G
SG3842G2, SG3843G
Vcc=10 to 20V
Ta=-40 to 85°C
Ta=25°C
Min.
49
49
8
Typ.
52
52
12
2.60
2.00
1.40
1.30
0.2
0.02
9
Max.
55
54
16
Unit
kHz
kHz
kHz
V
V
V
V
%
%/°C
mA
-
-
7
1
-
12
Note 1: F
OSC-G
is the last PWM frequency before completely turned off @ Vcc=15V
Error Amplifier Section
Symbol
V
FB
Iib
Avol
BW
PSRR
Isource
Isink
V
H COMP
V
L COMP
Parameter
Input voltage
Input bias current
Open-loop voltage gain
Unity gain bandwidth
Power supply rejection ratio
Output source current
Output sink current
Output voltage
Output voltage
Test Condition
Comp=2.5V
-
-
-
-
FB=2.3V,COMP=0V
FB=2.7V,COMP=1V
FB=2.3V, R
L
=15K to GND
FB=2.7V, R
L
=15K to VREF
Min.
2.45
-
45
0.7
50
-0.8
2
6
-
Typ.
2.5
-
55
1.2
-
-1.8
6.5
6.6
-
Max.
2.55
0.1
-
-
-
-3
-
-
700
Unit
V
uA
dB
MHz
dB
mA
mA
V
mV
Current Sense Section
Symbol
AV
Parameter
Current sense input voltage gain (n)
Test Condition
SG3842G
Min.
4.60
Typ.
5.00
Max.
5.40
Unit
V/V
© System General Corp.
Version 1.4 ( IRO33.0007.B3)
-4-
www.sg.com.tw
Jun.28,2004
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