TL3842 5
TL3842 5
TL3842 5
D GND
NC 6 9
Double-Pulse Suppression 7 8
RT/CT POWER GROUND
D High-Current Totem-Pole Output
D Internally Trimmed Bandgap Reference NC – No internal connection
D 500-kHz Operation
D
D-8 OR P PACKAGE
Error Amplifier With Low Output (TOP VIEW)
Resistance
D Designed to Be Interchangeable With COMP 1 8 REF
UC2842 and UC3842 Series VFB 2 7 VCC
ISENSE 3 6 OUTPUT
description RT/CT 4 5 GND
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.
PRODUCTION DATA information is current as of publication date. Copyright 1999, Texas Instruments Incorporated
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
AVAILABLE OPTIONS
PACKAGED DEVICES
CHIP FORM
TA SMALL OUTLINE SMALL OUTLINE PLASTIC DIP (Y)
(D) (D-8) (P)
TL3842D TL3842D-8 TL3842P TL3842Y
TL3843D TL3843D-8 TL3843P TL3843Y
0°C to 70°C
TL3844D TL3844D-8 TL3844P TL3844Y
TL3845D TL3845D-8 TL3845P TL3845Y
TL2842D TL2842D-8 TL2842P –
TL2843D TL2843D-8 TL2843P –
–40°C to 85°C
TL2844D TL2844D-8 TL2844P –
TL2845D TL2845D-8 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.
34 V NOM UVLO
5-V REF
14
9 – + EN REF
GND
Internal
Bias
Vref
11
Good VC
Logic
7 10
RT/CT OSC OUTPUT
†
T 8 POWER
GROUND
Error
Amplifier S
+ 2R
3 PWM
VFB – R
Latch
R 1V
1 Current-
COMP
Sense
5 Comparator
ISENSE
† The toggle flip-flop is present only in TL2844, TL2845, TL3844, and TL3845.
Pin numbers shown are for the D Package.
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)†
Supply voltage (see Note 1) (ICC < 30 mA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Self limiting
Analog input voltage range, VI (VFB and ISENSE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to 6.3 V
Output voltage, VO (OUTPUT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 V
Input voltage, VI, (VC, D package only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 V
Supply current, ICC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 mA
Output current, IO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±1 A
Error amplifier output sink current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 mA
Package thermal impedance, θJA (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, TJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 150°C
Output energy (capacitive load) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 µJ
Lead temperature, 1,6 mm (1/16 inch) from case for 10 seconds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260°C
Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –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), θJA, and TA. The maximum allowable power dissipation at any allowable
ambient temperature is PD = (TJ(max) – TA)/θJA. Operating at the absolute maximum TJ of 150°C can impact reliability.
3. The package thermal impedance is calculated in accordance with JESD 51.
electrical characteristics over recommended operating free-air temperature range, VCC = 15 V (see
Note 4), RT = 10 kΩ, CT = 3.3 nF (unless otherwise specified)
reference section
TL284x TL384x
PARAMETER TEST CONDITIONS UNIT
MIN TYP† MAX MIN TYP† MAX
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
0.2 0.4 0.2 0.4 mV/°C
of output voltage
Output voltage
VCC = 12 V to 25 V, IO = 1 mA to 20 mA 4.9 5.1 4.82 5.18 V
with worst-case variation
Output noise voltage f = 10 Hz to 10 kHz, TA = 25°C 50 50 µV
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
TL284x TL384x
PARAMETER TEST CONDITIONS UNIT
MIN TYP† MAX MIN TYP† MAX
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
TL284x TL384x
PARAMETER TEST CONDITIONS UNIT
MIN TYP† MAX MIN TYP† MAX
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 µA
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 kΩ to GND 5 6 5 6 V
Low-level output voltage VFB at 2.7 V, RL = 15 kΩ 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.
electrical characteristics over recommended operating free-air temperature range, VCC = 15 V (see
Note 4), RT = 10 kΩ, CT = 3.3 nF (unless otherwise specified) (continued)
current-sense section
TL284x TL384x
PARAMETER TEST CONDITIONS UNIT
MIN TYP† MAX MIN TYP† MAX
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 µA
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
TL284x TL384x
PARAMETER TEST CONDITIONS UNIT
MIN TYP† MAX MIN TYP† MAX
IOH = –20 mA 13 13.5 13 13.5
High level output voltage
High-level V
IOH = –200 mA 12 13.5 12 13.5
IOL = 20 mA 0.1 0.4 0.1 0.4
Low level output voltage
Low-level V
IOL = 200 mA 1.5 2.2 1.5 2.2
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
TL284x TL384x
PARAMETER UNIT
MIN TYP† MAX MIN TYP† MAX
TLx842, TLx844 15 16 17 14.5 16 17.5
Start threshold voltage V
TLx843, TLx845 7.8 8.4 9 7.8 8.4 9
TLx842, TLx844 9 10 11 8.5 10 11.5
Minimum operating voltage after startup V
TLx843, TLx845 7 7.6 8.2 7 7.6 8.2
† 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
TL284x TL384x
PARAMETER UNIT
MIN TYP† MAX MIN TYP† MAX
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.
electrical characteristics over recommended operating free-air temperature range, VCC = 15 V (see
Note 4), RT = 10 kΩ, CT = 3.3 nF (unless otherwise specified) (continued)
supply voltage
TL284x TL384x
PARAMETER TEST CONDITIONS UNIT
MIN TYP† MAX MIN TYP† MAX
Start-up current 0.5 1 0.5 1 mA
Operating supply current VFB and ISENSE at 0 V 11 17 11 17 mA
Limiting voltage ICC = 25 mA 34 34 V
† All typical values are at TA = 25°C.
NOTE 4: Adjust VCC above the start threshold before setting it to 15 V.
electrical characteristics, VCC = 15 V (see Note 4), RT = 10 kΩ, CT = 3.3 nF, TA = 25°C (unless otherwise
specified)
reference section
TL384xY
PARAMETER TEST CONDITIONS UNIT
MIN TYP MAX
Output voltage IO = 1 mA 5 V
Line regulation VCC = 12 V to 25 V 6 mV
Load regulation IO = 1 mA to 20 mA 6 mV
Temperature coefficient of output voltage 0.2 mV/°C
Output noise voltage f = 10 Hz to 10 kHz 50 µV
Output-voltage long-term drift After 1000 h at TA = 25°C 5 mV
Short-circuit output current –100 mA
NOTE 4: Adjust VCC above the start threshold before setting it to 15 V.
oscillator section
TL384xY
PARAMETER TEST CONDITIONS UNIT
MIN TYP MAX
Oscillator frequency (see Note 5) 52 kHz
Frequency change with supply voltage VCC = 12 V to 25 V 2 Hz/kHz
Frequency change with temperature 5 Hz/kHz
Peak-to-peak amplitude at RT/CT 1.7 V
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.
electrical characteristics, VCC = 15 V (see Note 4), RT = 10 kΩ, CT = 3.3 nF, TA= 25°C (unless otherwise
specified) (continued)
error-amplifier section
TL384xY
PARAMETER TEST CONDITIONS UNIT
MIN TYP MAX
Feedback input voltage COMP at 2.5 V 2.50 V
Input bias current –0.3 µA
Open-loop voltage amplification VO = 2 V to 4 V 90 dB
Gain-bandwidth product 1 MHz
Supply-voltage rejection ratio VCC = 12 V to 25 V 70 dB
Output sink current VFB at 2.7 V, COMP at 1.1 V 6 mA
Output source current VFB at 2.3 V, COMP at 5 V –0.8 mA
High-level output voltage VFB at 2.3 V, RL = 15 kΩ to GND 6 V
Low-level output voltage VFB at 2.7 V, RL = 15 kΩ to GND 0.7 V
NOTE 4: Adjust VCC above the start threshold before setting it to 15 V.
current-sense section
TL384xY
PARAMETER TEST CONDITIONS UNIT
MIN TYP MAX
Voltage amplification See Notes 6 and 7 3 V/V
Current-sense comparator threshold COMP at 5 V, See Note 6 1 V
Supply-voltage rejection ratio VCC = 12 V to 25 V, See Note 6 70 dB
Input bias current –2 µA
Delay time to output 150 ns
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
TL384xY
PARAMETER TEST CONDITIONS UNIT
MIN TYP MAX
IOH = –20 mA 13.5
High level output voltage
High-level V
IOH = –200 mA 13.5
IOL = 20 mA 0.1
Low level output voltage
Low-level V
IOL = 200 mA 1.5
Rise time CL = 1 nF 50 ns
Fall time CL = 1 nF 50 ns
NOTE 4: Adjust VCC above the start threshold before setting it to 15 V.
undervoltage-lockout section
TL384xY
PARAMETER UNIT
MIN TYP MAX
TL3842Y, TL3844Y 16
Start threshold voltage V
TL3843Y, TL3845Y 8.4
TL3842Y, TL3844Y 10
Minimum operating voltage after startup V
TL3843Y, TL3845Y 7.6
NOTE 4: Adjust VCC above the start threshold before setting it to 15 V.
electrical characteristics, VCC = 15 V (see Note 4), RT = 10 kΩ, CT = 3.3 nF, TA = 25°C (unless otherwise
specified) (continued)
pulse-width-modulator section
TL384xY
PARAMETER UNIT
MIN TYP MAX
TL3842Y, TL3843Y 97%
Maximum duty cycle
TL3844Y, TL3845Y 48%
NOTE 4: Adjust VCC above the start threshold before setting it to 15 V.
supply voltage
TL384xY
PARAMETER TEST CONDITIONS UNIT
MIN TYP MAX
Start-up current 0.5 1 mA
Operating supply current VFB and ISENSE at 0 V 11 17 mA
Limiting voltage ICC = 25 mA 34 V
NOTE 4: Adjust VCC above the start threshold before setting it to 15 V.
APPLICATION INFORMATION
2.5 V
Error 0.5 mA
Amplifier
VFB +
Zi –
COMP
Zf
Error
IS Amplifier
(see Note A) 2R
+
–
R 1V
Current-Sense
COMP Comparator
Rf
ISENSE
RS Cf
GND
REF
RT
(see Note A)
RT/CT
CT
GND
APPLICATION INFORMATION
R T – Timing Resistance – kΩ
CT = 1 nF
10
Dead Time – µ s
4 CT = 22 nF
10
CT = 47 nF
1
4 CT = 100 nF
0.4
VCC = 15 V
TA = 25°C
0.1 1
0 4 10 40 100 100 1k 10 k 100 k 1M
CT – Timing Capacitance – nF f - Frequency - Hz
Figure 4 Figure 5
RT
4.7 kΩ A VCC
2N2222
DUT REF
100 kΩ
COMP
1 kΩ 0.1 µF
Error Amplifier VFB VCC
TL284x
Adjust TL384x 0.1 µF
ISENSE 1 kΩ, 1 W
5 kΩ OUTPUT OUTPUT
4.7 kΩ
ISENSE
RT/CT GND
Adjust
GND
CT
APPLICATION INFORMATION
shutdown technique
The PWM controller (see Figure 7) can be shut down by two methods: either raise the voltage at ISENSE above
1 V or pull the COMP terminal below a voltage two diode drops above ground. Either method causes the output
of the PWM comparator to be high (refer to block diagram). The PWM latch is reset dominant so that the output
remains low until the next clock cycle after the shutdown condition at the COMP or ISENSE terminal is removed.
In one example, an externally latched shutdown can be accomplished by adding an SCR that resets by cycling
VCC below the lower UVLO threshold. At this point, the reference turns off, allowing the SCR to reset.
1 kΩ
REF
COMP
Shutdown
330 Ω ISENSE
Shutdown 500 Ω
To Current-Sense
Resistor
A fraction of the oscillator ramp can be resistively summed with the current-sense signal to provide slope
compensation for converters requiring duty cycles over 50% (see Figure 8). Note that capacitor C forms a filter
with R2 to suppress the leading-edge switch spikes.
REF
0.1 µF RT
RT/CT
CT
R1 ISENSE
R2
ISENSE
C
RSENSE
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any product or service without notice, and advise customers to obtain the latest version of relevant information
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pertaining to warranty, patent infringement, and limitation of liability.
TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in
accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent
TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily
performed, except those mandated by government requirements.
In order to minimize risks associated with the customer’s applications, adequate design and operating
safeguards must be provided by the customer to minimize inherent or procedural hazards.
TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent
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