Post on 03-Apr-2018
transcript
7/29/2019 PEexp03_voltage ref.pdf
1/16
3-1
Exp.3Voltage Reference
How to get the info you need from a data sheet?
1. Device name (part no.), features and descriptions2. Internal block diagram and pin configuration3. Absolute maximum ratings, recommended operating
conditions
4. Electrical characteristics, typical test circuits5. Performance characteristics6. Typical applications7.
Mechanical dimensions of case
7/29/2019 PEexp03_voltage ref.pdf
2/16
3-2
Voltage Reference TL431 Data sheet p.1
A three-terminal (R, A
and K) adjustable
voltage reference IC
Vo or VKA can be
adjusted to any value betweenVref(2.5 V)
and 36 V
Sink current capability
and TC
Three available cases
7/29/2019 PEexp03_voltage ref.pdf
3/16
3-3
Voltage Reference TL431 Data sheet p.2 - Internal block diagram and equiv. ckt
VREF is about 2.5 V
w.r.t. Anode
VKA can be set to be
equal to or larger than VREF
by external connections.
7/29/2019 PEexp03_voltage ref.pdf
4/16
3-4
Voltage Reference TL431 Data sheet p.2
7/29/2019 PEexp03_voltage ref.pdf
5/16
3-5
Voltage Reference TL431 Data sheet p.3
7/29/2019 PEexp03_voltage ref.pdf
6/16
3-6
Voltage Reference TL431 Data sheet p.4 - Test circuits
For VKA = VREF For VKA VREF
VKA = VREF(1 + R1/R2) + IREFR1
7/29/2019 PEexp03_voltage ref.pdf
7/16
3-7
Voltage Reference TL431 Data sheet p.4 - Test circuits
For IKA(OFF)
The current-limiting R must be designed so thatIKA(MIN) IKA IKA(MAX)
7/29/2019 PEexp03_voltage ref.pdf
8/16 3-8
Voltage Reference TL431 Data sheet p.5 - Performance characteristics
7/29/2019 PEexp03_voltage ref.pdf
9/16
3-9
Voltage Reference TL431 Data sheet p.5 - Performance characteristics
7/29/2019 PEexp03_voltage ref.pdf
10/16
3-10
Voltage Reference TL431 Data sheet p.5 - Performance characteristics
7/29/2019 PEexp03_voltage ref.pdf
11/16
3-11
Voltage Reference TL431 Data sheet p.6 - Typical applications
Shunt regulator
VO =
2R
1R
1 VREF
7/29/2019 PEexp03_voltage ref.pdf
12/16
3-12
Voltage Reference TL431 Data sheet p.6 - Typical applications
Output control for 3-terminal fixed regulator
VO =
2R
1R1 VREF
7/29/2019 PEexp03_voltage ref.pdf
13/16
3-13
Voltage Reference TL431 Data sheet p.6 - Typical applications
High current shunt regulator
VO =
2R
1R1 VREF
7/29/2019 PEexp03_voltage ref.pdf
14/16
3-14
Voltage Reference TL431 Data sheet p.6 - Typical applications
Current source or current limit
IO =CL
REF
R
V
7/29/2019 PEexp03_voltage ref.pdf
15/16
3-15
Voltage Reference TL431 Data sheet p.6 - Typical applications
Constant-current sink
IO =S
REF
R
V
7/29/2019 PEexp03_voltage ref.pdf
16/16
3-16
Experiment 3
1. Use TL431 and design R1, R2 to obtain Vo = 5 V.
RC