TS3842B/3843B
High Performance Current Mode Controller
Designed for Off-Line and DC-to-DC
converter applications.
DIP-8
SOP-8
General Description
The TS3842B and TS3843B series are high performance fixed frequency current mode controllers.
This is specifically designed for Off-Line and DC-to-DC converter applications offering the designer a
cost effective solution with minimal external components. This integrated circuits feature a trimmed
oscillator for precise duty cycle control, a temperature compensated reference, high gain error
amplifier, current sensing comparator, and a high current totem pole output ideally suited for driving
a power MOSFET.
Also included are protective features consisting of input and reference undervoltage lockouts each
with hysteresis, cycle-by-cycle current limiting, programmable output deadtime, and a latch for
single pulse metering.
This device is available in 8-pin dual-in-line plastic packages as well as the 8-pin plastic surface
mount (SOP-8). The SOP-8 package has separate power and ground pins for the totem pole output
stage.
The TS3842B has UVLO thresholds of 16V (on) and 10V (off), ideally suited for off-line converters.
Features
Trimmed Oscillator Discharge Current for
Precise Duty Cycle Control
Current Mode Operation to 500KHz
Automatic Feed Forward Compensation
Latching PWM for Cycle-By-Cycle Current
Limiting
Internally Trimmed Reference with Undervoltage
Lockout
High Current Totem Pole Output
Undervoltage Lockout with Hystersis
Low Start-Up and Operating Current
Block Diagram
V
CC
V
ref
8(14)
R
R
R
T
/C
T
4(7)
Voltage
Feedback
Input
2(3)
Output
Compensation
1(1)
V
ref
Undervoltage
Lockout
5.0V
Reference
7(12)
V
CC
Undervoltage
Lockout
V
C
7(11)
Output
Oscillator
Latching
PWM
+
-
Ordering Information
OPERATING TEMPERATURE
(Ambient)
-20 to +85+
DEVICE
TS3842/3843BCD
TS3842/3843BCS
PACKAGE
DIP-8
SOP-8
6(10)
Power
Ground
5(8)
Current
Sense
3(5)Input
Error
Amplifier
The document contains information on a new product.Specifications and
information herein are subject to change without notice.
Absolute Maximum Ratings
RATING
SYMBOL
VALUE
UNIT
Total Power Supply and Zener Current
Output Current Source or Sink (Note 1)
Output Energy (Capacitive Load per Cycle)
Current Sense and Voltage Feedback Inputs
Error Amp Output Sink Current
Power Dissipation and Thermal Characteristics
Plastic DIP
Maximum Power Dissipation @ T
A
=25+
Thermal Resistance Junction to Air
Plastic SOP
Maximum Power Dissipation @ T
A
=25+
Thermal Resistance Junction to Air
(I
CC
+I
Z
)
Io
W
Vin
Io
30
1.0
5.0
-0.3 to +5.5
10
mA
A
µJ
V
mA
P
D
R
θJA
P
D
R
θJA
T
J
T
A
Tstg
-20
862
145
1.25
100
0 to +150
to +85
-25 to +150
mW
+/W
W
+/W
+
+
+
Operating Junction Temperature
Operating Ambient Temperature
Storage Temperature Range
Electrical Characteristics
V
CC
=15V (Note 2), R
T
=10K, C
T
=3.3nF, T
A
=T
low
to T
high
(Note 3), unless otherwise noted.
CHARACTERISTIC
REFFRENCE SECTION
Reference Output Voltage (Io=1.0mA,T
J
= 25+)
Line Regulation (V
CC
=12V to 25V)
Load Regulation (Io =1.0mA to 20mA)
Temperature Stability
Total Output Variation over Line,Load ,and
Temperature
Output Noise Voltage (f = 10Hz to 10kHz, T
J
=25+)
Long Term Stability ( T
A
=125+ for 1000 Hours)
Output Short Circuit Current
OSCILLATOR SECTION
Frequency
T
J
=25+
T
A
=T
low
to T
high
Frequency Change with Voltage (V
CC
=12V to 25V)
Frequency Change with Temperature
fosc/ T
T
A
=T
low
to T
high
Oscillator Voltage Swing ( Peak-to-Peak)
Discharge Current (Vosc=2.0V)
T
J
=25+
T
A
=T
low
to T
high
Idischg
7.5
7.2
8.4
-
9.3
9.5
mA
Vosc
-
1.6
-
V
-
5.0
-
%
fosc/ V
Fosc
47
46
-
52
-
0.2
57
60
1.0
%
KHz
Vref
Regline
Regload
Ts
Vref
Vn
S
Isc
4.9
-
-
-
4.82
-
-
-30
5.0
2.0
3.0
0.2
-
50
5.0
-85
5.1
20
25
-
5.18
-
-
180
V
mV
mV
mV/+
V
µV
mV
mA
SYMBOL
MIN
TYP
MAX
UNIT
Electrical Characteristics
V
CC
=15V (Note 2), R
T
=10K, C
T
=3.3nF, T
A
=T
low
to T
high
(Note 3), unless otherwise noted.
CHARACTERISTIC
ERROR AMPLIFIER SECTION
Voltage Feedback Input (Vo=2.5V)
Input Bias Current (V
FB
=5.0V)
Open-Loop Voltage Gain (Vo=2.0V to 4.0V)
Unity Gain Bandwidth (T
J
=25+)
Power Supply Rejection Radio (V
CC
=12V to 25V)
Output Current
Sink (Vo=1.1V, V
FB
=2.7V)
Source ( Vo=5.0V, V
FB
=2.3V)
Output Voltage Swing
High State (R
L
=15K to ground, V
FB
=2.3V)
Low State (R
L
=15K to Vref, V
FB
=2.7V)
CURRENT SENSE SECTION
Current Sense Input Voltage Gain (Note 4&5)
Maximum Current Sense Input Threshold(Note 4)
Power Supply Rejection Radio
PSRR
V
CC
=12V to 25V,Note 4
Input Bias Current
Propagation Delay(Current Sense Input to Output)
I
IB
t
PLH(IN/OUT)
-
-
-2.0
150
-10
300
µA
ns
-
70
-
dB
Av
V
th
2.85
0.9
3.0
1.0
3.15
1.1
V/V
V
V
OH
V
OL
5.0
-
6.2
0.8
-
1.1
V
I
sink
I
Source
2.0
-0.5
12
-1.0
-
-
mA
V
FB
I
IB
A
VOL
BW
PSRR
2.42
-
65
0.7
60
2.5
-0.1
90
1.0
70
2.58
-2.0
-
-
-
V
a
A
dB
MHz
dB
SYMBOL
MIN
TYP
MAX
UNIT
Electrical Characteristics
V
CC
=15V (Note 2), R
T
=10K, C
T
=3.3nF, T
A
=T
low
to T
high
(Note 3), unless otherwise noted.
CHARACTERISTIC
OUTPUT SECTION
Output Voltage
Low State (Isink=20mA)
(Isink=200mA)
High State (Isource=20mA)
(Isource=200mA)
Output Voltage with UVLO Activated
V
CC
=6.0V,Isink=1.0mA
Output Voltage Rise Time (C
L
=1.0nF,T
J
=25+)
Output Voltage Fall Time (C
L
=1.0nF,T
J
=25+)
UNDERVOLTAGE LOCKOUT SECTION
Start-Up Threshold
TS3842B
TS3843B
Minimum Operating Voltage After Turn-On
TS3842B
TS3843B
PWM SECTION
Duty Cycle
Maximum
Minimum
TOTAL DEVICE
Power Supply Current
Start-Up, V
CC
= 14V
Operating (Note 2)
Power Supply Zener Voltage (I
CC
=25mA)
Vz
I
CC
-
-
30
0.25
12
36
0.5
17
-
V
mA
DCmax
DCmin
94
-
96
-
-
0
%
V
CC(min)
8.5
7.0
10
7.6
11.5
8.2
V
Vth
14.5
7.8
16
8.4
17.5
9.0
V
tr
tf
-
-
50
50
150
150
ns
ns
V
OL
(UVLO)
V
OH
V
OL
-
-
13
12
-
0.1
1.6
13.5
13.4
0.1
0.4
2.2
-
-
1.1
V
V
SYMBOL
MIN
TYP
MAX
UNIT
Note: 1. Maximum package power dissipation limits must be observed.
2. Adjust V
CC
above the Start-Up threshold before setting to 15V.
3. Low duty cycle pulse technique are used during test to maintain junction temperature as close to ambient as possible.
T
low
= -20
+
,T
high
= +85
+
4. This parameter is measured at the latch trip point with V
FB
= 0V.
V Output Compensation
5. Comparator gain is defined as : Av =
V Current Sense Input
Embedded System
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