AUK S3882

S3882
Semiconductor
Current Mode PWM Controller
Descriptions
The S3882 is fixed PWM controller for Off-line and DC-DC converter applications. The
internal circuits include UVLO, low start up current circuit, temperature compensated
reference, high gain error amplifier, current sensing comparator, and high current
totempole output for driving a power MOSFET.
Also S3882 provide low start up current below 0.3mA and short shutdown delay
Time typical 100nsec.
S3882 have UVLO threshold of 16V(on) and 10V(off).
.
Features
• Low start up current < 0.3mA
• Operating range up to 500KHz
• Cycle by cycle current limiting
• Under Voltage Lock Out with hysteresis
• Short shutdown delay time ; typical 100nsec
• High current totempole output
• Output swing limiting : 22V
Ordering Information
Type NO.
S3882
Marking
S3882
Package Code
SOP-8
Outline Dimensions
unit : mm
PIN Connections
1. Output / Compensation
2. Voltage feedback. Input
3. Current sense Input
4. Rt/Ct
5. GND
6. Output
7. Vcc
8. Vref
KSI-8008-001
1
S3882
Absolute Maximum Ratings
Ta=25°C
Characteristic
Symbol
Ratings
Unit
Supply Voltage
Vcc
28
V
Output Current
Io
1
A
Vi(ana)
-0.3 to 6.3
V
Isink(EA)
10
mA
Pd
1
W
Analog Inputs
Error Amp. Output Sink current
Power Dissipation
Electrical Characteristics
(Vcc=15V, Rt=10Kohm,Ct=3.3nF, Ta=0℃to 70℃, Unless otherwise specified)
Characteristic
Symbol
Test Condition
Min.
Typ. Max.
Unit
1. Reference Section
Output Voltage
Vref
Tj=25℃, Io=1mA
4.91
5.00
5.09
V
Line Regulation
Δ Vref
12V ≤ VCC ≤ 25V
-
6
20
mV
Load Regulation
Δ Vref
1mA ≤ IO ≤ 20mA
-
6
25
mV
Isc
Ta=25°C
-180
-100
-
mA
Initial Accuracy
fOSC
Tj=25℃
47
52
57
KHz
Voltage Stability
△f /△V
-
0.2
1.0
%
Oscillator Voltage
VOSC
Vpin4, peak to peak
1.4
1.7
1.8
V
Discharge Current
Idischarge
Tj=25°C, Pin4=2V
7.8
8.3
8.8
mA
Output Short Current
2. Oscillator Section
12V ≤ VCC ≤ 25V
3. Error Amp Section
Input Voltage
V2
VPIN1=2.5V
2.42
2.50
2.58
V
Input Bias Current
Ib
-
-2.0
-0.3
-
㎂
Open Loop Voltage Gain
AVO1
2V ≤ VO ≤ 4V
65
90
-
㏈
Unity Gain Bandwidth
GBW
Tj=25°C
0.7
1
-
MHz
VCC=12V to 25V
60
70
-
㏈
2
6
-
mA
-0.8
-0.5
mA
PSRR
Output Sink Current
Output Source Current
PSRR1
ISINK
ISOURCE
VPIN2=2.7V, VPIN1=1.1V
VPIN2=2.3V, VPIN1=5V
Output High Voltage
VOH
Vpin2=2.3V, R1=15 ㏀ to GN
5
6
-
V
Output Low Voltage
VOL
VPIN2=2.3V, R1=15 ㏀ to PIN8
-
0.8
1.1
V
GV
-
2.85
3.0
3.15
V/V
0.9
1.0
1.1
V
-
70
-
㏈
-10
-2
-
㎂
-
100
200
nS
4. Current Sense Section
Gain
Maximum Input Signal
Vi(MaX)
VPIN 1=5V
PSRR
PSRR2
12V ≤ VCC ≤ 25V
Input Bias Current
Delay to Output
I
bias
Td
VPIN 3=0V to 2V
KSI-8008-001
2
S3882
Electrical Characteristics(continued)
(Vcc=15V, Rt=10Kohm, Ct=3.3nF, Ta=0℃ to 70℃, Unless otherwise specified)
Characteristic
Symbol
Test Condition
Min.
Typ. Max.
Unit
5. Output Section
Output Low Level1
VOL1
Isink=20mA
-
0.1
0.4
V
Output Low Level2
VOL2
Isink=200mA
-
1.5
2.0
V
Output High Level1
VOH1
Isource=20mA
13.0
13.5
-
V
Output High Level2
VOH2
Isource=200mA
12.0
13.5
-
V
Rise Time
tr
Tj=25°C, C1=1nF
-
40
100
nS
Fall Time
tf
Tj=25°C, C1=1nF
-
40
100
nS
Vcc=27V, C1=1nF
-
22
-
V
15
16
17
V
9
10
11
V
Out Volt. Swing Limit
Volim
6. Under Voltage Lockout Section
Start Threshold
Vth
-
Min. Operating Voltage
VtL
After turn on
7.PWM Section
Maximum Duty Cycle
Dmax
-
94
96
100
%
Minimum Duty Cycle
Dmin
-
-
-
0
%
Start-Up Current
Ist
-
-
0.2
0.4
mA
Operating Supply Current
ICC
Vpin2=Vpin3=0V
-
11
17
mA
ICC=25mA
-
29
-
V
8.Total Standby Section
VCC Zener Voltage
VZ
NOTE: Adjust Vcc above the the start threshold before setting at 15V
Block Diagram
7
Vcc
5
GND
29V
Vref
5V
V ref
8
Set/
Re s e t
UV LO
LO G IC
In t e r n al
Bi as
PWR Vc
1/2 V r e f
Er r or Amp
Vfb
2
+
-
C.S Comp
1/3
7
PWM
LATCH
R
Output
22V
6
1V
S
Com 1
PWR GND
5
C.S
3
Rt/Ct
4
Os c i l l at or
KSI-8008-001
3
S3882
Information in Using IC
1. Under voltage Lockout
To prevent erratic output behavior which activating
V cc
7
the power switch with extraneous leakage currents,
O N /O F F C O M M A N D
T O R ES ET O F IC
during under voltage lockout. Output(pin6) should be
shunted to ground with a bleeder resister.
V o n -16V
V o f f -10V
The Vcc comparator upper and lower threshold are
Icc
16V/10V. The large hysteresis and low start up
currents makes it ideally suited in off-line converter
application where efficient bootstrap start-up
<17mA
techniques are required.
<1mA
V cc
16V
10V
2. Oscillator Waveforms and Maximum Duty Cycle
The oscillator frequency is programmed by the values
LARGE Rt
SMALL Ct
Vpin4
8
selected for the timing components Rt and Ct. Ct is
charged from 5V, Vref, through resistor Rt to
Rt
INTERNAL
CLOCK
4
Ct
SMALL Rt
LARGE Ct
Vpin4
5
INTERNAL
CLOCK
approximately 2.8V and discharged to 1.2V by an
internal current sink.
During the discharge of Ct, the oscillator generates an
internal blanking pulse and the center input NOR gate high.
This makes output to be in a low state and control the
amount of output dead time.
3. Error AMP Configuration
2.50V
Error amp output(Pin1) is provided for external loop
+
0.5mA
compensation and error amp can source or sink up to 0.5mA.
The non-inverting input is internally biased at 2.5V and is
V in
Zt
2
-
not pinned out. The converter output voltage is typically
divided down and monitored by the inverting input(pin2).
COMP
Zf
1
KSI-8008-001
4
S3882
4. Current Sense Circuit
ER R O R
A MP
2R
Iβ
R
IV
1
R (V p i n 1 - 2V b e )
CUR R ENT
S E NS E
C O MP A R A T O R
CO MP
Ip e a k =
R
3R x R s
3
C
CUR R E NT
S ENS E
G ND
Rs
5
A normal operating conditions occurs when the power supply output is overloaded or if output voltage to 1.0V
Therefore the maximum peak switch current is lpk(max)=1.0V/Rs, and under the normal operating conditions the
peak inductor current controlled by the voltage at pin1.
5. Shutdown Techniques
4.7K
8
V
3
4.7K
1
RE F
CO MP
accomplished by two methods;
ISEN SE
either raise pin3 above 1V or pull
5.00
S HUT
DO W N
Shutdown of the S3882 can be
pin1 below a voltage two diodes
S HUT
DO W N
drops above ground. Either causes
T O CUR R E NT
S E NS E R ES I S T O R
the output of the PWM method
comparator
to be high (refer to
block diagram). The PWM latch is reset dominant so that the output will remain low until the next clock cycle after
the shutdown condition at pins 1 and/or 3 is removed. In one example, an externally latched shutdown may be
accomplished by adding an SCR which turn off, allowing the SCR to reset.
KSI-8008-001
5
S3882
6. Open Loop Test
V REF
RT
2N2222
4 7K
ERROR
1K
AMP
ADJUST
4 7K
Vcc
100K
1 COMP
2
I SENSE
ADJUST
3
4
V REF
S3882
Vin
Vcc
OUTPUT
I SENSE
R T/CT
GND
5
0.1uF
6
7
0.1uF
1K/1W
OUTPUT
8
High peak currents associated with capacitive leads necessitate careful grounding techniques. Timing and bypass
capacitors should be connected close to Pin5 in a single point ground. The transistor and 5 ㏀ potentiometer are
used to sample the oscillator waveform and apply an adjustable ramp to Pin 3.
7.Slope Compensation
V
A fraction of the oscillator ramp can be resistively
0.1u F
RE F
8
summed with the current sense signal to provide
RT
R T /C T
4
CT
slope compensation for converters requiring duty
cycle over 50%. Note that capacitor C, forms a
R1
R2
I SEN SE
I SEN SE
3
C
filter with R2 to suppress the leading edge switch
spikes.
R SEN SE
KSI-8008-001
6
S3882
Electrical Characteristic Curves
OUTPUT DEAD-TIME vs.
OSCILLATOR FREQUENCY
TIMING RESISTOR vs.
OSCILLATOR FREQUENCY
80
V c c =15V
Ta = 25o C
50
50
5.0n F
2.0n F
R T TIMING RESISTOR (KΩ)
%DT PERCENT OUTPUT DEAD-TIME
100
1.0n F
20
Ct =10n F
500pF
10
5.0
200pF
100pF
2.0
1.0
10K
20K
50K
100K
200K
500K 1.0M
500pF
20
200pF
8.0
5.0
2.0
V c c =15V
Ta = 25o C
0.8
10K
20K
2.0n F 1.0n F
C T =10n F
50K
100K
200K
500K 1.0M
f OSC OS CILLATOR FREQUENCY (KHz )
f OSC OS CILLATOR FREQUENCY (KHz )
Error Amplifier Open-Loop
Frequency Response
Output Saturation Characteristics
0
80
-45
60
φ
40
-90
o
)
20
-135
AV
0
SATURATION VOLTAGE (V)
4
PHASE (
VOLTAGE GAIN (dB)
100pF
5.0n F
Vcc=15V
Ta = 25o C
3
Ta=-55o C
2
SOURCE SAT(Vcc-VOH)
1
-180
SINK SAT(VOL)
0
10
100
1K
10K
100K
1M
10M
0.1
0.2
0.3 0.4 0.5 0.7
1
2
3
4
5
7
10
OUTPUT CURRENT SOURCE OR SINK (A)
FREQUENCY (Hz)
KSI-8008-001
7
S3882
These AUK products are intended for usage in general electronic equipments(Office and
communication equipment, measuring equipment, domestic electrification, etc.).
Please make sure that you consult with us before you use these AUK products in equipments which require high quality and/or reliability, and in equipments which could have
major impact to the welfare of human life(atomic energy control, airplane, spaceship, traffic
signal, combustion central, all types of safety device, etc.).
AUK cannot accept liability to any damage which may occur in case these AUK products
were used in the mentioned equipments without prior consultation with AUK.
KSI-8008-001
8