TSC TS3842B, TS3843B Technical data

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TS3842B/3843B

High Performance Current Mode Controller

Designed for Off-Line and DC-to-DC
converter applications.

SOP-8DIP-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 Ordering Information

V

7(12)

CC

PWM

V

CC

Undervoltage

Lockout

V
7(11)

Output
6(10)

5(8)

3(5)

C

Power
Ground

Current
Sense
Input

DEVICE

TS3842/3843BCD
TS3842/3843BCS

OPERATING TEMPERATURE

-20 to +85

V

ref

8(14)

R

T/CT

4(7)

Voltage

Feedback

Input

2(3)

Output

Compensation

1(1)

The document contains information on a new product.Specifications and

R

R

Undervoltage

Oscillator

+

-

Error

Amplifier

information herein are subject to change without notice.

V

ref

Lockout

5.0V

Reference

Latching

(Ambient)

PACKAGE



DIP-8

SOP-8

Absolute Maximum Ratings

RATING SYMBOL VALUE UNIT

Total Power Supply and Zener Current (ICC+IZ) 30 mA
Output Current Source or Sink (Note 1) Io 1.0 A
Output Energy (Capacitive Load per Cycle) W 5.0 µJ
Current Sense and Voltage Feedback Inputs Vin -0.3 to +5.5 V
Error Amp Output Sink Current Io 10 mA
Power Dissipation and Thermal Characteristics
Plastic DIP

Maximum Power Dissipation @ T

=25

A

Thermal Resistance Junction to Air

Plastic SOP

Maximum Power Dissipation @ T

Thermal Resistance Junction to Air

=25

A

P

D

θ

JA

R

P

D

θ

JA

R

862
145

1.25
100

Operating Junction Temperature TJ 0 to +150 
Operating Ambient Temperature TA -20 to +85 
Storage Temperature Range Tstg -25 to +150 

mW

/W

W

/W



Electrical Characteristics

VCC=15V (Note 2), RT=10K, CT=3.3nF, TA=T

low

to T

(Note 3), unless otherwise noted.

high

CHARACTERISTIC SYMBOL MIN TYP MAX UNIT

REFFRENCE SECTION

Reference Output Voltage (Io=1.0mA,T
Line Regulation (V

=12V to 25V)

CC

= 25)

J

Vref 4.9 5.0 5.1 V

Regline - 2.0 20 mV
Load Regulation (Io =1.0mA to 20mA) Regload - 3.0 25 mV
Temperature Stability Ts - 0.2 -

Total Output Variation over Line,Load ,and
Temperature

Output Noise Voltage (f = 10Hz to 10kHz, T
Long Term Stability ( T

=125 for 1000 Hours)

A

=25)

J

Vref 4.82 - 5.18 V

Vn - 50 - µV

S-5.0-mV

mV/

Output Short Circuit Current Isc -30 -85 180 mA

OSCILLATOR SECTION

Frequency
T

=25



J

to T

T

A=Tlow

high

Frequency Change with Voltage (V
Frequency Change with Temperature
T

to T

A=Tlow

high

=12V to 25V)

CC

Fosc

fosc/V



fosc/T



47 52 57
46 - 60

-0.21.0%

-5.0-

KHz

%

Oscillator Voltage Swing ( Peak-to-Peak) Vosc - 1.6 - V
Discharge Current (Vosc=2.0V)
T

J

T

A=Tlow

=25



to T

high

Idischg

7.5 8.4 9.3

7.2 - 9.5

mA



Electrical Characteristics

VCC=15V (Note 2), RT=10K, CT=3.3nF, TA=T

low

to T

(Note 3), unless otherwise noted.

high

CHARACTERISTIC SYMBOL MIN TYP MAX UNIT

ERROR AMPLIFIER SECTION

Voltage Feedback Input (Vo=2.5V)
Input Bias Current (V

=5.0V) I

FB

Open-Loop Voltage Gain (Vo=2.0V to 4.0V)
Unity Gain Bandwidth (T
Power Supply Rejection Radio (V

=25)

J

=12V to 25V)

CC

V

FB

IB

A

VOL

2.42 2.5 2.58 V

- -0.1 -2.0

65 90 - dB

a

BW 0.7 1.0 - MHz

PSRR 60 70 - dB
Output Current
Sink (Vo=1.1V, V
Source ( Vo=5.0V, V

=2.7V) I

FB

=2.3V) I

FB

sink

Source

2.0 12 -

-0.5 -1.0 -

mA

Output Voltage Swing
High State (R
Low State (R

=15K to ground, VFB=2.3V) V

L

=15K to Vref, VFB=2.7V) V

L

OH

OL

5.0 6.2 -

-0.81.1

CURRENT SENSE SECTION

Current Sense Input Voltage Gain (Note 4&5) Av 2.85 3.0 3.15 V/V
Maximum Current Sense Input Threshold(Note 4)
Power Supply Rejection Radio
V

=12V to 25V,Note 4

CC

Input Bias Current
Propagation Delay(Current Sense Input to Output)

V

th

0.9 1.0 1.1 V

PSRR - 70 - dB

I

IB

t

PLH(IN/OUT)

- -2.0 -10 µA

-150300ns

A

V

Electrical Characteristics

VCC=15V (Note 2), RT=10K, CT=3.3nF, TA=T

low

to T

(Note 3), unless otherwise noted.

high

CHARACTERISTIC SYMBOL MIN TYP MAX UNIT

OUTPUT SECTION

Output Voltage
Low State (Isink=20mA)

V

OL

-0.10.4
(Isink=200mA) - 1.6 2.2
High State (Isource=20mA)

V

OH

13 13.5 ­ (Isource=200mA) 12 13.4 ­Output Voltage with UVLO Activated

=6.0V,Isink=1.0mA

V

CC

Output Voltage Rise Time (C
Output Voltage Fall Time (C

=1.0nF,TJ=25)

L

=1.0nF,TJ=25)

L

(UVLO)

V

OL

-0.11.1V

tr - 50 150 ns
tf - 50 150 ns

UNDERVOLTAGE LOCKOUT SECTION
Start-Up Threshold

TS3842B 14.5 16 17.5

Vth V

TS3843B 7.8 8.4 9.0

Minimum Operating Voltage After Turn-On

TS3842B 8.5 10 11.5

V

CC(min)

TS3843B 7.0 7.6 8.2

PWM SECTION

Duty Cycle
Maximum DCmax 94 96 ­Minimum DCmin - - 0

TOTAL DEVICE

Power Supply Current
Start-Up, V

CC

= 14V

I

CC

- 0.25 0.5
Operating (Note 2) - 12 17
Power Supply Zener Voltage (I

=25mA)

CC

Vz 30 36 - V

V

V

%

mA

Note: 1. Maximum package power dissipation limits must be observed.

2. Adjust V

3. Low duty cycle pulse technique are used during test to maintain junction temperature as close to ambient as possible.
T

4. This parameter is measured at the latch trip point with VFB = 0V.

above the Start-Up threshold before setting to 15V.

CC

= -20 ,T

low

= +85

high







V Output Compensation





5. Comparator gain is defined as : Av =



V Current Sense Input



Figure 1 - Timing Resistor vs.

Oscillator Frequency

80
20

Figure 2 - Output Dead Time vs.

Oscillator Frequency

100

50

20

8.0

5.0

RT. TIMING RESISTOR (KΩ)

2.0

0.8
10K 20K 50K

fosc, OSCILLATOR FREQUENCY (KHz)

100K 200K 500K 1.0M

Figure 3 - Oscillator Discharge

Current vs. Temperature

9.0

8.5

8.0

7.5

Idischg. DISCHARGE CURRENT (mA)

7.0

T

. AMBIENT TEMPERATURE (oC)

A

75 100 12550250-25-55

Figure 5 - Error Amp Small

Signal Transient Response

20

10

5.0

2.0

% DT. PERCENT OUTPUT DEAD-TIME

1.0
10K 20K 50K

fosc, OSCILLATOR FREQUENCY (KHz)

100K 200K 500K 1.0M

Figure 4 - Maximum Output Duty

Cycle vs. Timing Resistor

100

90

80

70

60

50

Dmax. MAXIMUM OUTPUT DUTY CYCLE (%)

40

800 1.0K 2.0K 3.0K 4.0K 6.0K 8.0K

RT. TIMING RESISTOR (Ω)

Figure 6 - Error Amp Large
Signal Transient Response

2.55V

2.5V

2.45V

0.15µs/DIV

20mV/DIV

3.0V

2.0V

2.5V

200mA/DIV

10µs/DIV

Figure 7 - Error Amp Open-Loop

Gain and Phase vs. Frequency

100

Figure 8 - Current Sense Input Thresh-

0

old vs. Error Amp Output voltage

1.2

80

60

40

20

0

Avol.OPEN-LOOP VOLTAGE GAIN (dB)

-20
10 100

10K 100K 1.0M 10M

1.0K
f. FREQUENCY (Hz)

Figure 9 - Reference Voltage

Change vs. Source Current

0

-4.0

-8.0

-12

-16

-20

Vref. REFERENCE VOLTAGE CHANGE (mV)

r

-24
0 20 40 60 80 100 120

Iref.REFERENCE SOURCE CURRENT (mA)

Figure 11 - Reference Load

Regulation

30

60

90

120

150

EXCESS PHASE (DEGREES)

180

1.0

0.8

0.6

0.4

0.2

Vth. CURRENT SENSE INPUT THRESHOLD (V)

0

0 2.0 4.0 6.0 8.0

Vo. ERROR OUTPUT VOLTAGE (Vo)

Figure 10 - Reference Short Circuit

Current vs. Temperature

110

90

70

Isc. REFERENCE CIRCUIT CURRENT (mA)

50

0-25-55 5025 75 100 125

TA. AMBIENT TEMPERATURE (oC)

Figure 12 - Reference Line

Regulation

Vo.OUTPUT VOLTAGE CHANGE (2.0mV/DIV)

r

2.0ms/DIV

Vo.OUTPUT VOLTAGE CHANGE (2.0mV/DIV)

r

2.0ms/DIV