Product
Folder
Order
Now
Support &
Community
Tools &
Software
Technical
Documents
ATL431LI
ATL432LI
SLVSDU6D – JULY 2017 – REVISED NOVEMBER 2019
ATL431LI / ATL432LI High Bandwidth Low-Iq Programmable Shunt Regulator
1 Features
3 Description
•
The ATL43xLI device is a three-terminal adjustable
shunt regulator, with specified thermal stability over
applicable automotive, commercial, and military
temperature ranges. The output voltage can be set to
any value between Vref (approximately 2.5 V) and 36
V, with two external resistors. These devices have a
typical output impedance of 0.3 Ω. Active output
circuitry provides a very sharp turn-on characteristic,
making these devices excellent replacements for
Zener diodes in many applications, such as onboard
regulation, adjustable power supplies, and switching
power supplies. This device is a pin-to-pin alternative
to the TL431LI and TL432LI, with lower minimum
operating current to help reduce system power
consumption. The ATL432LI device has exactly the
same functionality and electrical specifications as the
ATL431LI device, but has a different pinout for the
DBZ package. The ATL431LI is also offered in a tiny
X2SON (1.00 mm x 1.00 mm) package which makes
it ideal for space constraint applications.
1
•
•
•
•
•
•
•
•
•
Reference voltage tolerance at 25°C
– 0.5% (B Grade)
– 1% (A Grade)
Minimum typical output voltage: 2.5 V
Adjustable output voltage: Vref to 36 V
Operation from −40°C to +125°C (Q temp)
Maximum temperature drift
– 17 mV (I Temp)
– 27 mV (Q Temp)
0.3-Ω Typical output impedance
Sink-current capability
– Imin = 0.08 mA (max)
– IKA = 15 mA (max)
Reference input current IREF: 0.4 μA (max)
Deviation of reference input current over
temperature, II(dev): 0.3 μA (max)
Packages: 1-mm x 1-mm X2SON or SOT23-3
The ATL431LI device is offered in two grades, with
initial tolerances (at 25°C) of 0.5%, and 1%, for the B
and A grade, respectively. In addition, low output drift
versus temperature ensures good stability over the
entire temperature range.
2 Applications
•
•
•
•
•
•
Adjustable voltage and current referencing
Secondary side regulation in Flyback SMPS
Zener diode replacement
Voltage monitoring
Precision constant current sink/source
Comparator with integrated reference
The ATL43xLIxQ devices are characterized for
operation from –40°C to +125°C.
Device Information(1)
PART NUMBER
PACKAGE (PIN)
BODY SIZE (NOM)
ATL43xLI
SOT-23 (3)
2.90 mm x 1.30 mm
ATL431LI
X2SON (4)
1.00 mm x 1.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Simplified Schematic
VKA
Input
IKA
Vref
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
ATL431LI
ATL432LI
SLVSDU6D – JULY 2017 – REVISED NOVEMBER 2019
www.ti.com
Table of Contents
1
2
3
4
5
6
7
8
9
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Device Comparison Table.....................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
3
4
7.1
7.2
7.3
7.4
7.5
4
4
4
4
5
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Thermal Information ..................................................
Recommended Operating Conditions.......................
Electrical Characteristics...........................................
Typical Characteristics.......................................... 6
Parameter Measurement Information .................. 9
9.1 Temperature Coefficient............................................ 9
9.2 Dynamic Impedance ............................................... 10
10 Detailed Description ........................................... 11
10.1 Overview ............................................................... 11
10.2 Functional Block Diagram ..................................... 11
10.3 Feature Description............................................... 12
10.4 Device Functional Modes...................................... 12
11 Applications and Implementation...................... 13
11.1 Application Information.......................................... 13
11.2 Typical Applications .............................................. 13
11.3 System Examples ................................................. 21
12 Power Supply Recommendations ..................... 25
13 Layout................................................................... 25
13.1
13.2
13.3
13.4
Layout Guidelines .................................................
SOT23-3 Layout Example.....................................
X2SON (DQN) Layout Example............................
Thermal Considerations ........................................
25
25
25
26
14 Device and Documentation Support ................. 27
14.1
14.2
14.3
14.4
14.5
14.6
14.7
Documentation Support ........................................
Related Links ........................................................
Receiving Notification of Documentation Updates
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
27
27
27
27
27
27
28
15 Mechanical, Packaging, and Orderable
Information ........................................................... 28
4 Revision History
Changes from Revision C (August 2019) to Revision D
Page
•
Changed typical graph to match Electrical Characteristics ................................................................................................... 6
•
Added X2SON (DQN) Layout Example ............................................................................................................................... 25
•
Added Thermal Considerations ............................................................................................................................................ 26
Changes from Revision B (November 2018) to Revision C
Page
•
Changed Imin description to match Electrical Characteristics ................................................................................................. 1
•
Added X2SON package option .............................................................................................................................................. 1
•
Added X2SON pinout and specifications................................................................................................................................ 3
Changes from Revision A (October 2018) to Revision B
•
Page
Changed ATL43xLI from Product Preview to Production Data. ............................................................................................. 1
Changes from Original (July 2018) to Revision A
Page
•
Initial release of full version ................................................................................................................................................... 1
•
Changed Stability Boundary Conditions for All ATL431, ATL432 Devices Above 1 mA graph ............................................. 7
•
Added Stability Boundary Conditions for All ATL431, ATL432 Devices Below 1 mA graph ................................................. 7
•
Added Test Circuit for Stability Boundary Conditions image ................................................................................................. 7
2
Submit Documentation Feedback
Copyright © 2017–2019, Texas Instruments Incorporated
Product Folder Links: ATL431LI ATL432LI
ATL431LI
ATL432LI
www.ti.com
SLVSDU6D – JULY 2017 – REVISED NOVEMBER 2019
5 Device Comparison Table
DEVICE PINOUT
INITIAL ACCURACY
OPERATING FREE-AIR TEMPERATURE (TA)
ATL431LI
ATL432LI
A: 1%
B: 0.5%
I: -40°C to 85°C
Q: -40°C to 125°C
6 Pin Configuration and Functions
ATL431LI DBZ Package
3-Pin SOT-23
Top View
CATHODE
1
REF
2
3
ATL431LI DQN Package
4-Pin X2SON
Top View
ANODE
Thermal
Pad
ATL432LI DBZ Package
3-Pin SOT-23
Top View
REF
CATHODE
1
ANODE
1
3
CATHODE
3
REF
4
ANODE
2
NC
2
Pin Functions
PIN
NAME
ATL431LIx
ATL431LIx
ATL432LIx
DBZ
DQN
DBZ
TYPE
ANODE
3
1
3
O
Common pin, normally connected to ground
CATHODE
1
3
2
I/O
Shunt Current/Voltage input
REF
2
4
1
I
NC
N/A
2
N/A
—
No internal connection
Thermal Pad
N/A
Available
N/A
—
Connect to ground or to a floating copper
plane for mechanical stability.
Copyright © 2017–2019, Texas Instruments Incorporated
Product Folder Links: ATL431LI ATL432LI
DESCRIPTION
Threshold relative to common anode
Submit Documentation Feedback
3
ATL431LI
ATL432LI
SLVSDU6D – JULY 2017 – REVISED NOVEMBER 2019
www.ti.com
7 Specifications
7.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
MIN
VKA
Cathode Voltage (2)
IKA
Continuos Cathode Current Range
II(ref)
Reference Input Current
TJ
Tstg
(1)
(2)
MAX
UNIT
37
V
–10
18
mA
–5
10
mA
Operating Junction Temperature Range
–40
150
C
Storage Temperature Range
–65
150
C
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
All voltage values are with respect to ANODE, unless otherwise noted.
7.2 ESD Ratings
VALUE
Electrostatic
discharge
V(ESD)
(1)
(2)
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001pins (1)
±2000
Charged-device model (CDM), per JEDEC specification JESD22- ±1000
VC101 (2)
±1000
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
7.3 Thermal Information
ATL43xLI
THERMAL METRIC (1)
DBZ
DQN
3 PINS
4 PINS
UNIT
RθJA
Junction-to-ambient thermal resistance
371.7
173.7
C/W
RθJC(top)
Junction-to-case (top) thermal resistance
145.9
185.5
C/W
RθJB
Junction-to-board thermal resistance
104.7
119.9
C/W
ψJT
Junction-to-top characterization parameter
23.9
13.1
C/W
ψJB
Juction-to-board characterization parameter
102.9
119.9
C/W
RθJC(bottom)
Juction-to-case (bottom) thermal resistance
N/A
93.0
C/W
(1)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
7.4 Recommended Operating Conditions
See
(1)
MIN
MAX
UNIT
VKA
Cathode Voltage
VREF
36
V
IKA
Continuous Cathode Current Range
0.08
15
mA
TA
Operating Free-Air Temperature
ATL43xLIxI
–40
85
C
ATL43xLIxQ
–40
125
C
(1)
4
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 affect reliability.
Submit Documentation Feedback
Copyright © 2017–2019, Texas Instruments Incorporated
Product Folder Links: ATL431LI ATL432LI
ATL431LI
ATL432LI
www.ti.com
SLVSDU6D – JULY 2017 – REVISED NOVEMBER 2019
7.5 Electrical Characteristics
over recommended operating conditions, TA = 25°C (unless otherwise noted)
PARAMETER
TEST CIRCUIT
VREF
Reference Voltage
VI(dev)
Deviation of reference
input voltage over full
temperature range (1)
See Figure 17
VKA = Vref, IKA = 1 mA
ΔVref /
ΔVKA
Ratio of change in
reference voltage to the
change in cathode
voltage
See Figure 18
IKA = 1 mA
Iref
Reference Input Current See Figure 18
II(dev)
Deviation of reference
input current over full
temperature range (1)
Imin
Minimum cathode
current for regulation
Ioff
Off-state cathode
current
|ZKA|
(1)
(2)
Dynamic Impedance
See Figure 17
TEST CONDITIONS
(2)
VKA = Vref, IKA = 1 mA
MIN
TYP MAX
UNIT
ATL43xLIAx devices
2475 2500 2525
mV
ATL43xLIBx devices
2487 2500 2512
mV
ATL43xLIxI devices
6
17
mV
ATL43xLIxQ devices
10
27
mV
–1.4
–2.7
mV/V
–1
–2
mV/V
IKA = 1 mA, R1 = 10kΩ, R2 = ∞
0.2
0.4
µA
See Figure 18
IKA = 1 mA, R1 = 10kΩ, R2 = ∞
0.1
0.3
µA
See Figure 17
VKA = Vref
65
80
uA
See Figure 19
VKA = 36 V, Vref = 0
0.1
1
µA
See Figure 17
VKA = Vref, IKA = 1 mA to 15 mA
0.3
0.65
Ω
ΔVKA = 10 V - Vref
ΔVKA = 36 V - 10 V
The deviation parameters VI(dev) and II(dev) are defined as the differences between the maximum and minimum values obtained over the
rated temperature range. For more details on VI(dev) and how it relates to the average temperature coefficient, see Parameter
Measurement Information.
The dynamic impedance is defined by |ZKA| = ΔVKA/ΔIKA. For more details on |ZKA| and how it relates to VKA, see Parameter
Measurement Information.
Copyright © 2017–2019, Texas Instruments Incorporated
Product Folder Links: ATL431LI ATL432LI
Submit Documentation Feedback
5
ATL431LI
ATL432LI
SLVSDU6D – JULY 2017 – REVISED NOVEMBER 2019
www.ti.com
8 Typical Characteristics
Data at high and low temperatures are applicable only within the recommended operating free-air temperature
ranges of the various devices.
2.505
1
2.502
2.5005
2.499
2.4975
2.496
2.4945
2.493
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
2.4915
2.49
-50
0
-50
-25 0
25 50 75 100 125 150
TA - Free-Air Temperature - °C
Figure 1. Reference Voltage vs Free-Air Temperature
-25
0
25
50
75 100
TA - Free-Air Temperature - °C
125
D002
Figure 2. Reference Current vs Free-Air Temperature
200
15
VKA = Vref
175 T = 25°C
A
VKA = Vref
TA = 25°C
12
IKA - Cathode Current - µA
IKA - Cathode Current - mA
IKA = 1 mA
0.9
Iref - Reference Current - µA
Vref - Reference Voltage - V
Vka = Vref
2.5035 I = 1 mA
KA
9
6
3
0
150
125
Imin
100
75
50
25
0
-25
-50
-3
0.5
1
1.5
2
2.5
VKA - Cathode Voltage -V
0.5
1
1.5
2
VKA - Cathode Voltage - V
D003
2.5
D004
Figure 3. Cathode Current vs Cathode Voltage
Figure 4. Cathode Current vs Cathode Voltage
0.064
-0.35
VKA = 36 V
0.056 VREF = 0 V
VKA = 3 V to 36 V
-0.4
-0.45
0.048
0.04
0.032
0.024
0.016
-0.5
-0.55
-0.6
-0.65
-0.7
0.008
-0.75
0
-50
-25
0
25
50
75 100
TA - Free-Air Temperature - °C
125
Figure 5. Off-State Cathode Current
vs Free-Air Temperature
6
0
3
'Vref / 'VKA = mV/V
Ioff - Off-State Cathode Current - PA
0
Submit Documentation Feedback
-0.8
-50
-25
D004
0
25
50
75
Temperature (°C)
100
125
D006
Figure 6. Ratio of Delta Reference Voltage to Delta Cathode
Voltage vs Free-Air Temperature
Copyright © 2017–2019, Texas Instruments Incorporated
Product Folder Links: ATL431LI ATL432LI
ATL431LI
ATL432LI
www.ti.com
SLVSDU6D – JULY 2017 – REVISED NOVEMBER 2019
200
60
160
45
120
30
80
15
40
IKA = 10 mA
TA = 25°C
Output
Phase - q
AV - Small-Signal Voltage Amplification - dB
Typical Characteristics (continued)
75
IKA
15 kΩ
9 µF
+
AV
Phase
0
100
1k
10k
100k
f - Frequency - Hz
0
10M
1M
232 Ω
−
8.25 kΩ
D000
GND
Figure 7. Small-Signal Voltage Amplification
vs Frequency
Figure 8. Test Circuit for Voltage Amplification
|ZKA| - Reference Impedance - Ohms
100
1 kΩ
IKA = 1 mA
50 T = 25°C
A
30
20
IKA
10
50 Ω
5
3
2
−
+
1
GND
0.5
0.3
0.2
0.1
1k
10k
100k
f - Frequency - Hz
1M
Figure 9. Reference Impedance vs Frequency
Figure 10. Test Circuit for Reference Impedance
6
Input
Input and Output Voltage - V
Output
220 Ω
TA = 25qC
Output
5
Pulse
Generator
f = 100 kHz
4
3
Output
50 Ω
2
GND
1
0
-1
0
1
2
3
4
t - Time - Ps
5
6
7
puls
Figure 11. Pulse Response
Figure 12. Test Circuit for Pulse Response
Copyright © 2017–2019, Texas Instruments Incorporated
Product Folder Links: ATL431LI ATL432LI
Submit Documentation Feedback
7
ATL431LI
ATL432LI
SLVSDU6D – JULY 2017 – REVISED NOVEMBER 2019
www.ti.com
Typical Characteristics (continued)
150 Ω
15
IKA - Cathode Current - mA
13
A VKA = Vref
B VKA = 5 V
C VKA = 10 V
IKA
Stable Region
+
11
VBATT
CL
−
9
7
TEST CIRCUIT FOR CURVE A
5
3
1
0.001
IKA
R1 = 10 kΩ
0.01
0.1
1
CL - Load Capacitance - µF
150 Ω
10
ATL4
The areas under the curves represent conditions that may cause the
device to oscillate. For curves B and C, R2 and V+ are adjusted to
establish the initial VKA and IKA conditions, with CL = 0. VBATT and CL
then are adjusted to determine the ranges of stability.
Figure 13. Stability Boundary Conditions for All ATL431LI,
ATL432LI Devices Above 1 mA
CL
+
R2
VBATT
−
TEST CIRCUIT FOR CURVES B, C, AND D
Figure 14. Test Circuit for Stability Boundary Conditions
150 Ω
IKA - Cathode Current - mA
1
0.8
A VKA = Vref
B VKA = 5 V
C VKA = 10 V
IKA
+
VBATT
CL
−
0.6
0.4
TEST CIRCUIT FOR CURVE A
Stable Region
0.2
IKA
0
0.001
R1 = 10 kΩ
0.01
0.1
1
CL - Load Capacitance - µF
150 Ω
10
ATL4
The areas in-between the curves represent conditions that may cause
the device to oscillate. For curves B, and C, R2 and V+ are adjusted
to establish the initial VKA and IKA conditions, with CL = 0. VBATT and
CL then are adjusted to determine the ranges of stability.
Figure 15. Stability Boundary Conditions for All ATL431LI,
ATL432LI Devices Below 1 mA
CL
+
R2
VBATT
−
TEST CIRCUIT FOR CURVES B, C, AND D
Figure 16. Test Circuit for Stability Boundary Conditions
8
Submit Documentation Feedback
Copyright © 2017–2019, Texas Instruments Incorporated
Product Folder Links: ATL431LI ATL432LI
ATL431LI
ATL432LI
www.ti.com
SLVSDU6D – JULY 2017 – REVISED NOVEMBER 2019
9 Parameter Measurement Information
VKA
Input
IKA
Vref
Figure 17. Test Circuit for VKA = Vref
Input
VKA
IKA
R1
Iref
R2
Vref
R1 ö
æ
VKA = Vref ç 1 +
÷ + Iref × R1
R2 ø
è
Figure 18. Test Circuit for VKA > Vref
Input
VKA
Ioff
Figure 19. Test Circuit for Ioff
9.1 Temperature Coefficient
The deviation of the reference voltage, Vref, over the full temperature range is known as VI(dev). The parameter of
VI(dev) can be used to find the temperature coefficient of the device. The average full-range temperature
coefficient of the reference input voltage, αVref, is defined as:
αVref is positive or negative, depending on whether minimum Vref or maximum Vref, respectively, occurs at the
lower temperature. The full-range temperature coefficient is an average and therefore any subsection of the rated
operating temperature range can yield a value that is greater or less than the average. For more details on
temperature coefficient, check out Voltage Reference Selection Basics.
Copyright © 2017–2019, Texas Instruments Incorporated
Product Folder Links: ATL431LI ATL432LI
Submit Documentation Feedback
9
ATL431LI
ATL432LI
SLVSDU6D – JULY 2017 – REVISED NOVEMBER 2019
www.ti.com
9.2 Dynamic Impedance
'VKA
'IKA . When the device is operating with two external resistors
The dynamic impedance is defined as:
'V
z'
'I which is approximately equal to
(see Figure 18), the total dynamic impedance of the circuit is given by:
R1 ·
§
ZKA ¨ 1
¸
© R2 ¹ .
ZKA
Itest
P/
IKA (mA)
The VKA of the ATL431LI can be affected by the dynamic impedance. The ATL431LI test current Itest for VKA is
specified on the Eletrical Characteristics . Any deviation from Itest can cause deviation on the output VKA.
Figure 20 shows the effect of the dynamic impedance on the VKA.
IKA
IKA(min)
0
VKA (V)
Ps
Figure 20. Dynamic Impedance
10
Submit Documentation Feedback
Copyright © 2017–2019, Texas Instruments Incorporated
Product Folder Links: ATL431LI ATL432LI
ATL431LI
ATL432LI
www.ti.com
SLVSDU6D – JULY 2017 – REVISED NOVEMBER 2019
10 Detailed Description
10.1 Overview
This standard device has proven ubiquity and versatility across a wide range of applications, ranging from power
to signal path. This is due to its key components containing an accurate voltage reference and opamp, which are
very fundamental analog building blocks. ATL431LI is used in conjunction with its key components to behave as
a single voltage reference, error amplifier, voltage clamp or comparator with integrated reference.
ATL431LI can be operated and adjusted to cathode voltages from 2.5V to 36V, making this part optimal for a
wide range of end equipments in industrial, auto, telecom & computing. In order for this device to behave as a
shunt regulator or error amplifier, >80µA (Imin(maximum)) must be supplied in to the cathode pin. Under this
condition, feedback can be applied from the Cathode and Ref pins to create a replica of the internal reference
voltage.
Various reference voltage options can be purchased with initial tolerances (at 25°C) of 0.5%, and 1%. These
reference options are denoted by B (0.5%) and A (1.0%) after the ATL431LI or ATL432LI. ATL431LI and
ATL432LI are both functionally the same, but have separate pinout options.
The ATL43xLIxQ devices are characterized for operation from –40°C to +125°C.
10.2 Functional Block Diagram
CATHODE
+
REF
_
Vref
ANODE
Figure 21. Equivalent Schematic
CATHODE
REF
ANODE
Figure 22. Detailed Schematic
Copyright © 2017–2019, Texas Instruments Incorporated
Product Folder Links: ATL431LI ATL432LI
Submit Documentation Feedback
11
ATL431LI
ATL432LI
SLVSDU6D – JULY 2017 – REVISED NOVEMBER 2019
www.ti.com
10.3 Feature Description
ATL431LI consists of an internal reference and amplifier that outputs a sink current based on the difference
between the reference pin and the virtual internal pin. The sink current is produced by the internal Darlington
pair, shown in the above schematic (Figure 21). A Darlington pair is used in order for this device to be able to
sink a maximum current of 15 mA.
When operated with enough voltage headroom (≥ 2.5 V) and cathode current (IKA), ATL431LI forces the
reference pin to 2.5 V. However, the reference pin can not be left floating, as it needs IREF ≥ 0.4 µA ( see
Specifications). This is because the reference pin is driven into an NPN, which needs base current in order
operate properly.
When feedback is applied from the Cathode and Reference pins, ATL431LI behaves as a Zener diode,
regulating to a constant voltage dependent on current being supplied into the cathode. This is due to the internal
amplifier and reference entering the proper operating regions. The same amount of current needed in the above
feedback situation must be applied to this device in open loop, servo or error amplifying implementations in order
for it to be in the proper linear region giving ATL431LI enough gain.
Unlike many linear regulators, ATL431LI is internally compensated to be stable without an output capacitor
between the cathode and anode. However, if it is desired to use an output capacitor Figure 13 can be used as a
guide to assist in choosing the correct capacitor to maintain stability.
10.4 Device Functional Modes
10.4.1 Open Loop (Comparator)
When the cathode/output voltage or current of ATL431LI is not being fed back to the reference/input pin in any
form, this device is operating in open loop. With proper cathode current (Ika) applied to this device, ATL431LI will
have the characteristics shown in SLVA987. With such high gain in this configuration, ATL431LI is typically used
as a voltage comparator. The integrated voltage reference makes the ATL431LI a flexible device for monitoring a
signal for undervoltage and overvoltage detection.
10.4.2 Closed Loop
When the cathode/output voltage or current of ATL431LI is being fed back to the reference/input pin in any form,
this device is operating in closed loop. The majority of applications involving ATL431LI use it in this manner to
regulate a fixed voltage or current. The feedback enables this device to behave as an error amplifier, computing
a portion of the output voltage and adjusting it to maintain the desired regulation. This is done by relating the
output voltage back to the reference pin in a manner to make it equal to the internal reference voltage, which can
be accomplished via resistive or direct feedback.
12
Submit Documentation Feedback
Copyright © 2017–2019, Texas Instruments Incorporated
Product Folder Links: ATL431LI ATL432LI
ATL431LI
ATL432LI
www.ti.com
SLVSDU6D – JULY 2017 – REVISED NOVEMBER 2019
11 Applications and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
11.1 Application Information
As this device has many applications and setups, there are many situations that this datasheet can not
characterize in detail. The linked application notes will help the designer make the best choices when using this
part.
Application note Understanding Stability Boundary Conditions Charts in TL431, TL432 Data Sheet, SLVA482
provides a deeper understanding of this device's stability characteristics and aid the user in making the right
choices when choosing a load capacitor. Application note Setting the Shunt Voltage on an Adjustable Shunt
Regulator, SLVA445 assists with setting the shunt voltage to achieve optimum accuracy for this device.
11.2 Typical Applications
11.2.1 Comparator With Integrated Reference
Vsup
Rsup
Vout
CATHODE
R1
VIN
RIN
REF
VL
+
R2
2.5V
ANODE
Figure 23. Comparator Application Schematic
Copyright © 2017–2019, Texas Instruments Incorporated
Product Folder Links: ATL431LI ATL432LI
Submit Documentation Feedback
13
ATL431LI
ATL432LI
SLVSDU6D – JULY 2017 – REVISED NOVEMBER 2019
www.ti.com
Typical Applications (continued)
11.2.1.1 Design Requirements
For this design example, use the parameters listed in Table 1 as the input parameters.
Table 1. Design Parameters
DESIGN PARAMETER
EXAMPLE VALUE
Input Voltage Range
0 V to 5 V
Input Resistance
10 kΩ
Supply Voltage
24 V
Cathode Current (Ik)
5 mA
Output Voltage Level
~2 V – VSUP
Logic Input Thresholds VIH/VIL
VL
11.2.1.2 Detailed Design Procedure
When using ATL431LI as a comparator with reference, determine the following:
• Input Voltage Range
• Reference Voltage Accuracy
• Output logic input high and low level thresholds
• Current Source resistance
11.2.1.2.1 Basic Operation
In the configuration shown in Figure 23 ATL431LI will behave as a comparator, comparing the VREF pin voltage
to the internal virtual reference voltage. When provided a proper cathode current (IK), ATL431LI will have enough
open loop gain to provide a quick response. This can be seen in Figure 24, where the RSUP=10 kΩ (IKA=500 µA)
situation responds much slower than RSUP=1 kΩ (IKA=5 mA). With the ATL431LI max Operating Current (IMIN)
being 0.08 mA, operation near that could result in low gain, leading to a slow response.
11.2.1.2.1.1 Overdrive
Slow or inaccurate responses can also occur when the reference pin is not provided enough overdrive voltage.
This is the amount of voltage that is higher than the internal virtual reference. The internal virtual reference
voltage will be within the range of 2.5 V ±(0.5% or 1.0%) depending on which version is being used. The more
overdrive voltage provided, the faster the ATL431LI will respond.
For applications where ATL431LI is being used as a comparator, it is best to set the trip point to greater than the
positive expected error (that is +1.0% for the A version). For fast response, setting the trip point to >10% of the
internal VREF should suffice.
For minimal voltage drop or difference from Vin to the ref pin, TI recommends to use an input resistor
工商网监
湘ICP备2023018690号
