Adjustable Precision
Shunt Regulator
Description
The
CYT432
is a low voltage three terminal
adjustable shunt regulator with a guaranteed thermal
stability over applicable temperature ranges. The output
voltage can be set to any value between V
REF
(approximately 1.24 V) to 12V with two external resistors.
This device has a typical output impedance of 0.25Ω.
Active output circuitry provides a very sharp turn on
characteristic, making this device excellent replacement
for Zener diodes in many applications.
The
CYT432
is characterized for operation from 0
o
C
to
105
o
C,
and
four
package
options
(SOT-23-3,
CYT432
Features
Low voltage operation (1.24V)
Adjustable output voltage V
0
=V
REF
to 12V
Wide operating current range 60µA to 100mA
Low dynamic output impedance 0.25Ω (Typ.)
Trimmed bandgap design up to + 0.5%.
ESD rating is 4KV(Per MIL-STD-883D)
Available in Lead-Free Packages.
Application
Linear Regulators
Adjustable Supplies
Switching Power Supplies
Battery Operated Computers
Instrumentation
Computer Disk Drives
SOT-23-5, TO-92 and SOP-8) allow the designer the
opportunity to select the proper package for their
applications.
Pin Configuration
SOT-23-3, SC59-3L
(Top View)
SOT-23-5L
(Top View)
SOP-8
(Top View)
TO-92
(Top View)
Marking Information
Package
SOT-23-3
SC59-3L
Marking
CYT
432W
Production Year Code
Starting with S, a bar on top of S is for production
year 2001, and underlined S is for year 2002.
The next character is marked on top for 2003, and
Production Week Code
Lead-Free Package
Lead-free package is
indicated by a dot on
top of the week code.
A-Z: 1-26
a-z: 27-52
SOT-23-5L
CYT
432W
CYT432
YYWW
CYT432
YYWW
underlined for 2004. The naming pattern continues
with consecutive characters for later years.
SOP-8
WW is for the week of
YY is for the year of production. 04 means
the product is manufactured in year of 2004.
production.
26 means the
Lead-free
package
is
TO-92
product is manufactured in
the 26
th
week
indicated by LF after
YYWW.
All contents are subject to change without prior notice.
1
Adjustable Precision
Shunt Regulator
Absolute Maximum Rating
Parameter
Cathode Voltage
Continuous Cathode Current
Reference Current
Operating Junction Temperature Range
Storage Temperature Range
Symbol
V
KA
I
KA
I
REF
T
J
T
STG
Maximum
12
150
3
150
-45 to 150
230 (SOT-23-3)
Thermal Resistance
θ
JA
230 (SOT-23-5)
150 (SOP-8)
220 (TO-92)
Lead Temperature (Soldering) 10 seconds
T
LEAD
260
CYT432
Units
V
mA
mA
°C
°C
°C/W
°C
Electrical Characteristics
Parameter
1.250V ± 0.5%
Reference
Voltage
1.240V ± 0.5%
1.240V ± 1.0%
1.240V ± 1.5%
1.240V ± 2.0%
Deviation of Reference Voltage over
Full Temperature Range
Ratio of Change in Reference Voltage
to the Change in Cathode Voltage
Reference Current
Test circuit #1
V
I(DEV)
V
KA
= V
REF
, I
KA
= 10mA,
T
A
= 0°C - 105°C
∆V
REF
/∆VKA
Test circuit #2
I
KA
= 10mA,
∆V
KA
= 12V to V
REF
Test circuit #2
I
KA
= 10mA, R1=10kΩ, R2 =
∞
Test circuit #2
I
I(DEV)
I
KA
= 10mA, R1=10kΩ, R2 =
∞
T
A
= 0°C - 105°C
I
MIN
Test circuit #1
V
KA
= V
REF
Test circuit #3
V
KA
= 12V, V
REF
= 0
Test circuit #1
Dynamic Impedance
| Z
KA
|
I
KA
= 100µA - 80mA,
V
KA
= V
REF
, f
≤
1kHZ
--
0.25
1
Ω
--
60
100
µA
--
0.10
0.50
µA
--
-1.0
-2.7
mV/V
--
10
25
mV
V
REF
Test circuit #1
V
KA
= V
REF
, I
KA
= 10mA
Symbol
Test Conditions & Circuit
Min
1246
1234
1228
1221
1215
Typ
1250
1240
1240
1240
1240
Max
1256
1246
1252
1259
1265
mV
Unit
I
REF
--
0.15
2
µA
Deviation of Reference Current over
Full Temperature Range
Minimum Cathode Current for
Regulation
Off-state Cathode Current
I
OFF
--
0.04
0.8
µA
All contents are subject to change without prior notice.
2
Adjustable Precision
Shunt Regulator
Typical Performance Characteristics
Cathode Current VS Cathode
Voltage
150
125
Cathode Current (mA)
100
75
50
25
0
-25
-50
-75
-100
-2
-1
0
1
2
Cathode Voltage (V)
VKA = Vref
TA = 25C
CYT432
Cathode Current VS Cathode
Voltage
500
400
Cathode Current (uA)
300
200
100
0
-100
-200
-1
0
1
2
Cathode Voltage (V)
VKA = Vref
TA = 25C
Reference Voltage VS Junction
Temperature
1260
Reference Input Current VS Junction Temperature
1000
R1 = 10k
Ω
R2 =
∞
I
KA
=10mA
Reference Current (nA)
120
Reference Voltage (mV)
1250
1240
1230
1220
1210
1200
-20
0
20
40
60
800
Iz=10mA
600
Iz=60µA
400
200
80
100
Junction Temperature (C)
0
- 20
0
20
40
60
80
100
120
Junction Temperature (C)
All contents are subject to change without prior notice.
3
Adjustable Precision
Shunt Regulator
Stability Boundary Condition
100
CYT432
80
IKA (mA)
60
40
20
0
0.001
0.01
0.1
1
CL (uF)
VKA=VREF (1.24V)
VKA=2V
VKA=3V
The areas under the curves represent conditions that may cause the device to oscillate. For V
KA
= 2V
and 3V curves, R2 and V
BAT
were adjusted to establish the initial V
KA
and I
K
conditions with CL = 0. V
BAT
and
C
L
then were adjusted to determine the ranges of stability. As the graph suggested,
CYT432
is unconditional
stable with I
K
from 0 to 100mA and with C
L
from 0.001uF to 1uF.
All contents are subject to change without prior notice.
4
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