TL284x, TL384x
CURRENT-MODE PWM CONTROLLERS
SLVS038E JANUARY 1989 REVISED DECEMBER 1999
1
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
D
Optimized for Off-Line and dc-to-dc
Converters
D
Low Start-Up Current (<1 mA)
D
Automatic Feed-Forward Compensation
D
Pulse-by-Pulse Current Limiting
D
Enhanced Load-Response Characteristics
D
Undervoltage Lockout With Hysteresis
D
Double-Pulse Suppression
D
High-Current Totem-Pole Output
D
Internally Trimmed Bandgap Reference
D
500-kHz Operation
D
Error Amplifier With Low Output
Resistance
D
Designed to Be Interchangeable With
UC2842 and UC3842 Series
description
The TL284x and TL384x series of control
integrated circuits provide the features that are
necessary to implement off-line or dc-to-dc fixed-frequency current-mode control schemes with a minimum
number of external components. Some of the internally implemented circuits are an undervoltage lockout
(UVLO), featuring a start-up current of less than 1 mA, and a precision reference trimmed for accuracy at the
error amplifier input. Other internal circuits include logic to ensure latched operation, a pulse-width modulation
(PWM) comparator (which also provides current-limit control), and a totem-pole output stage designed to source
or sink high-peak current. The output stage, suitable for driving N-channel MOSFETs, is low when it is in the
off state.
Major differences between members of these series are the UVLO thresholds and maximum duty-cycle ranges.
Typical UVLO thresholds of 16 V (on) and 10 V (off) on the TLx842 and TLx844 devices make them ideally suited
to off-line applications. The corresponding typical thresholds for the TLx843 and TLx845 devices are 8.4 V (on)
and 7.6 V (off). The TLx842 and TLx843 devices can operate to duty cycles approaching 100%. A duty-cycle
range of 0 to 50% is obtained by the TLx844 and TLx845 by the addition of an internal toggle flip-flop, which
blanks the output off every other clock cycle.
The TL284x-series devices are characterized for operation from 40
C to 85
C. The TL384x-series devices are
characterized for operation from 0
C to 70
C.
Copyright
1999, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
1
2
3
4
5
6
7
14
13
12
11
10
9
8
COMP
NC
VFB
NC
ISENSE
NC
RT/CT
REF
NC
V
CC
VC
OUTPUT
GND
POWER GROUND
D PACKAGE
(TOP VIEW)
1
2
3
4
8
7
6
5
COMP
VFB
ISENSE
RT/CT
REF
V
CC
OUTPUT
GND
D-8 OR P PACKAGE
(TOP VIEW)
NC No internal connection
TL284x, TL384x
CURRENT-MODE PWM CONTROLLERS
SLVS038E JANUARY 1989 REVISED DECEMBER 1999
2
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
AVAILABLE OPTIONS
PACKAGED DEVICES
CHIP FORM
TA
SMALL OUTLINE
(D)
SMALL OUTLINE
(D-8)
PLASTIC DIP
(P)
CHIP FORM
(Y)
0
C to 70
C
TL3842D
TL3843D
TL3844D
TL3845D
TL3842D-8
TL3843D-8
TL3844D-8
TL3845D-8
TL3842P
TL3843P
TL3844P
TL3845P
TL3842Y
TL3843Y
TL3844Y
TL3845Y
40
C to 85
C
TL2842D
TL2843D
TL2844D
TL2845D
TL2842D-8
TL2843D-8
TL2844D-8
TL2845D-8
TL2842P
TL2843P
TL2844P
TL2845P
The D and D-8 packages are available taped and reeled. Add the suffix R to the device type (i.e.,
TL3842DR or TL3842DR-8).
Chip forms are tested at 25
C.
functional block diagram
The toggle flip-flop is present only in TL2844, TL2845, TL3844, and TL3845.
Pin numbers shown are for the D Package.
Internal
Bias
Vref
Good
Logic
OSC
5-V REF
Error
Amplifier
PWM
Latch
Current-
Sense
Comparator
34 V NOM
VCC
GND
RT/CT
VFB
COMP
ISENSE
12
9
7
3
1
5
14
11
10
8
REF
VC
OUTPUT
POWER
GROUND
+
UVLO
EN
2R
R
1 V
S
R
T
+
TL284x, TL384x
CURRENT-MODE PWM CONTROLLERS
SLVS038E JANUARY 1989 REVISED DECEMBER 1999
3
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
Supply voltage (see Note 1) (I
CC
< 30 mA)
Self limiting
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Analog input voltage range, V
I
(VFB and ISENSE)
0.3 V to 6.3 V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output voltage, V
O
(OUTPUT)
35 V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input voltage, V
I
, (VC, D package only)
35 V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Supply current, I
CC
30 mA
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output current, I
O
1 A
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Error amplifier output sink current
10 mA
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Package thermal impedance,
JA
(see Notes 2 and 3): D package
86
C/W
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
D-8 package
97
C/W
. . . . . . . . . . . . . . . . . . . . . . . . . .
P package
85
C/W
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Virtual junction temperature range, T
J
0
C to 150
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output energy (capacitive load)
5
J
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lead temperature, 1,6 mm (1/16 inch) from case for 10 seconds
260
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage temperature range, T
stg
65
C to 150
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
NOTES:
1. All voltages are with respect to the device GND terminal.
2. Maximum power dissipation is a function of TJ(max),
JA, and TA. The maximum allowable power dissipation at any allowable
ambient temperature is PD = (TJ(max) TA)/
JA. Operating at the absolute maximum TJ of 150
C can impact reliability.
3. The package thermal impedance is calculated in accordance with JESD 51.
recommended operating conditions
MIN
NOM
MAX
UNIT
Supply voltage, VCC and VC
30
V
Input voltage, VI, RT/CT
0
5.5
V
Input voltage, VI, VFB and ISENSE
0
5.5
V
Output voltage, VO, OUTPUT
0
30
V
Output voltage, VO, POWER GROUND
0.1
1
V
Supply current, externally limited, ICC
25
mA
Average output current, IO
200
mA
Reference output current, IO(ref)
20
mA
Oscillator frequency, fosc
100
500
kHz
Operating virtual junction temperature, TJ
0
125
C
Operating free air temperature T
TL284x
40
85
C
Operating free-air temperature, TA
TL384x
0
70
C
These recommended voltages for VC and POWER GROUND apply only to the D package.
TL284x, TL384x
CURRENT-MODE PWM CONTROLLERS
SLVS038E JANUARY 1989 REVISED DECEMBER 1999
4
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
electrical characteristics over recommended operating free-air temperature range, V
CC
= 15 V (see
Note 4), R
T
= 10 k
, C
T
= 3.3 nF (unless otherwise specified)
reference section
PARAMETER
TEST CONDITIONS
TL284x
TL384x
UNIT
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
UNIT
Output voltage
IO = 1 mA,
TA = 25
C
4.95
5
5.05
4.9
5
5.1
V
Line regulation
VCC = 12 V to 25 V
6
20
6
20
mV
Load regulation
IO = 1 mA to 20 mA
6
25
6
25
mV
Temperature coefficient
of output voltage
0.2
0.4
0.2
0.4
mV/
C
Output voltage
with worst-case variation
VCC = 12 V to 25 V,
IO = 1 mA to 20 mA
4.9
5.1
4.82
5.18
V
Output noise voltage
f = 10 Hz to 10 kHz,
TA = 25
C
50
50
V
Output-voltage long-term drift
After 1000 h at TA = 25
C
5
25
5
25
mV
Short-circuit output current
30
100
180
30
100
180
mA
All typical values are at TA = 25
C.
NOTE 4: Adjust VCC above the start threshold before setting it to 15 V.
oscillator section
PARAMETER
TEST CONDITIONS
TL284x
TL384x
UNIT
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
UNIT
Oscillator frequency (see Note 5)
TA = 25
C
47
52
57
47
52
57
kHz
Frequency change with supply voltage
VCC = 12 V to 25 V
2
10
2
10
Hz/kHz
Frequency change with temperature
50
50
Hz/kHz
Peak-to-peak amplitude at RT/CT
1.7
1.7
V
All typical values are at TA = 25
C.
NOTES:
4. Adjust VCC above the start threshold before setting it to 15 V.
5. Output frequency equals oscillator frequency for the TLx842 and TLx843. Output frequency is one-half oscillator frequency for the
TLx844 and TLx845.
error-amplifier section
PARAMETER
TEST CONDITIONS
TL284x
TL384x
UNIT
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
UNIT
Feedback input voltage
COMP at 2.5 V
2.45
2.50
2.55
2.42
2.50
2.58
V
Input bias current
0.3
1
0.3
2
A
Open-loop voltage amplification
VO = 2 V to 4 V
65
90
65
90
dB
Gain-bandwidth product
0.7
1
0.7
1
MHz
Supply-voltage rejection ratio
VCC = 12 V to 25 V
60
70
60
70
dB
Output sink current
VFB at 2.7 V,
COMP at 1.1 V
2
6
2
6
mA
Output source current
VFB at 2.3 V,
COMP at 5 V
0.5
0.8
0.5
0.8
mA
High-level output voltage
VFB at 2.3 V,
RL = 15 k
to GND
5
6
5
6
V
Low-level output voltage
VFB at 2.7 V,
RL = 15 k
to GND
0.7
1.1
0.7
1.1
V
All typical values are at TA = 25
C.
NOTE 4: Adjust VCC above the start threshold before setting it to 15 V.
TL284x, TL384x
CURRENT-MODE PWM CONTROLLERS
SLVS038E JANUARY 1989 REVISED DECEMBER 1999
5
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
electrical characteristics over recommended operating free-air temperature range, V
CC
= 15 V (see
Note 4), R
T
= 10 k
, C
T
= 3.3 nF (unless otherwise specified) (continued)
current-sense section
PARAMETER
TEST CONDITIONS
TL284x
TL384x
UNIT
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
UNIT
Voltage amplification
See Notes 6 and 7
2.85
3
3.13
2.85
3
3.15
V/V
Current-sense comparator threshold
COMP at 5 V,
See Note 6
0.9
1
1.1
0.9
1
1.1
V
Supply-voltage rejection ratio
VCC = 12 V to 25 V,
See Note 6
70
70
dB
Input bias current
2
10
2
10
A
Delay time to output
150
300
150
300
ns
All typical values are at TA = 25
C.
NOTES:
4. Adjust VCC above the start threshold before setting it to 15 V.
6. These parameters are measured at the trip point of the latch, with VFB at 0 V.
7. Voltage amplification is measured between ISENSE and COMP, with the input changing from 0 V to 0.8 V.
output section
PARAMETER
TEST CONDITIONS
TL284x
TL384x
UNIT
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
UNIT
High level output voltage
IOH = 20 mA
13
13.5
13
13.5
V
High-level output voltage
IOH = 200 mA
12
13.5
12
13.5
V
Low level output voltage
IOL = 20 mA
0.1
0.4
0.1
0.4
V
Low-level output voltage
IOL = 200 mA
1.5
2.2
1.5
2.2
V
Rise time
CL = 1 nF,
TA = 25
C
50
150
50
150
ns
Fall time
CL = 1 nF,
TA = 25
C
50
150
50
150
ns
All typical values are at TA = 25
C.
NOTE 4: Adjust VCC above the start threshold before setting it to 15 V.
undervoltage-lockout section
PARAMETER
TL284x
TL384x
UNIT
PARAMETER
MIN
TYP
MAX
MIN
TYP
MAX
UNIT
Start threshold voltage
TLx842, TLx844
15
16
17
14.5
16
17.5
V
Start threshold voltage
TLx843, TLx845
7.8
8.4
9
7.8
8.4
9
V
Minimum operating voltage after startup
TLx842, TLx844
9
10
11
8.5
10
11.5
V
Minimum operating voltage after startup
TLx843, TLx845
7
7.6
8.2
7
7.6
8.2
V
All typical values are at TA = 25
C.
NOTE 4: Adjust VCC above the start threshold before setting it to 15 V.
pulse-width-modulator section
PARAMETER
TL284x
TL384x
UNIT
PARAMETER
MIN
TYP
MAX
MIN
TYP
MAX
UNIT
Maximum duty cycle
TLx842, TLx843
95%
97%
100%
95%
97%
100%
Maximum duty cycle
TLx844, TLx845
46%
48%
50%
46%
48%
50%
Minimum duty cycle
0
0
All typical values are at TA = 25
C.
NOTE 4: Adjust VCC above the start threshold before setting it to 15 V.
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