CAT431L
Low-Voltage Adjustable Precision Voltage Reference
- 0.5% Tolerance
FEATURES
s
Low startup overshoot
s
Wide current operation: 40µA to 100mA
s
Low temperature coefficient reference: +12mV
s
Low dynamic impedance: 0.3Ω at 1kHz
s
Compact 3-lead SOT23 package option
s
Industrial temperature range: -40°C to 85°C
°
°
s
Adjustable output voltage: V
REF
to 6V
- SOT23 and TO92 Packages
- Low Startup Overshoot
max deviation over temperature
s
Accurate 1.24V reference voltage: +0.5%
(+6mV) at 25°C
°
APPLICATIONS
s
SMPS control loop
s
Shunt regulator
s
Low temperature coefficient voltage reference
s
Current limiting
s
Over/Under voltage monitor
s
3V Off-line switching regulators
DESCRIPTION
The CAT431L is a low-voltage three-terminal
adjustable shunt voltage reference with guaranteed
thermal stability over the industrial temperature range.
The CAT431L has a lower 1.24V reference and wider
operating current range than the widely used TL431
and TL431A shunt-regulator references. Compared
to the TLV431/A, the CAT431L 1.24V reference is two
times more accurate.
Minimal overshoot at startup and wide AC bandwidth
make the CAT431L easy to apply in a wide set of
applications. When used with an opto-coupler, the
CAT431L is an ideal voltage reference in isolated
feedback circuits for 3V to 3.3V switch-mode power
supplies.
FUNCTIONAL DIAGRAM
CATHODE
CATHODE
REF
+
–
REF
1.24
VREF
ANODE
ANODE
© 2003 by Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
1
Doc. No. 4006, Rev. J
CAT431L
PIN CONFIGURATION
SOT-23
TOP VIEW
2 CATH
ANODE 3
1 REF
NC 1
NC 2
CATH 3
4 REF
SOT-23-5
TOP VIEW
5 ANODE
TO-92
TOP VIEW
CATH
ANODE
REF
PIN DESCRIPTIONS
Pin Name
CATH
REF
ANODE
Function
Output and supply terminal, must be greater than 1.24V for normal
operation
Input, nominally 1.24V in normal operation
Ground and Substrate
ORDERING INFORMATION
Part Number
CAT431LEUR-TE7
CAT431LEUK-TE7
CAT431LEZR-TEAP
TE7 = 7" Reel, 3,000 parts per reel
TEAP = Ammopack, 3,000 parts per reel
Package
3-Pin, SOT-23
5-Pin, SOT-23
3-Pin, TO-92
Ambient Temperature Range
-40
°
C to 85
°
C
-40
°
C to 85
°
C
-40
°
C to 85
°
C
Doc. No. 4006, Rev. J
2
CAT431L
ABSOLUTE MAXIMUM RATINGS
Cathode Voltage .................................................. 18V
REF Current ........................................................ 3mA
Cathode, Anode Currents ............................... 150mA
Operating Junction Temperature ..................... 150°C
Lead Soldering Temperature (10 sec) ............. 260°C
Storage Temperature Range ........... -65°C to +150°C
These are stress ratings only and functional operation is not
implied. Exposure to absolute maximum ratings for prolongued
time periods may affect device reliability. All voltages are with
respect to ground.
ELECTRICAL CHARACTERISTICS
Electrical characteristics are guaranteed over the full operating temperature range of -40°C to +85°C with a junction
temperature from -40°C to +105°C unless otherwise specified. Ambient temperature must be de-rated based upon
power dissipation and package thermal characteristics.
1
Symbol
V
REF
∆V
REF
∆V
REF
∆V
CATH
I
REF
∆I
REF
I
CATH(min)
I
CATH(OFF)
r
CATH
1.
Parameter
Reference Voltage
Conditions
V
REF
=V
CATH
I
CATH
=10mA
25
°
C
TEMP
Min
1.234
1.228
Typ
1.240
1.240
4
Max
1.246
1.252
12
1
0.4
0.2
40
100
Units
V
V
mV
mV/V
µA
µA
µA
nA
Ω
VREF Temperature deviation
Ratio of V
REF
Change to V
CATH
Change (Line Reg; 1/gain)
Reference input current
I
REF
Temperature Deviation
Minimum Cathode Current
Off-State Cathode Current
Dynamic Output Impedance
V
REF
=0V; V
CATH
=16V
I
CATH
=0.1 to 100mA
f=1.0kHz
I
CATH
=10mA
V
CATH
=V
REF
to 6V
I
CATH
=10mA
0.3
0.2
0.04
18
0.3
0.4
Thermal Characteristics (Θ
JA
)
3-lead, SOT-23: 336°C/W
5-lead, SOT-23: 255
3-pin, TO-92: 155
Recommended Operating Conditions
Parameter
Cathode Voltage
Cathode Current
Operating Ambient Temperature
Min
VREF
0.1
-40
Max
6
15
85
Units
V
mA
°
C
3
Doc. No. 4006, Rev. J
CAT431L
TYPICAL PERFORMANCE CHARACTERISTICS
Reference Voltage
vs.
Junction Temperature
1.246
1.244
250
Reference Input Current
vs.
Junction Temperature
Reference Input Current (nA)
240
230
220
210
200
190
180
170
160
150
-50
-25
0
25
50
75
100 125 150
Reference Voltage (V)
1.242
1.240
1.238
1.236
1.234
1.232
-50
-25
0
25
50
75
100 125 150
Junction Temperature (°C)
Junction Temperature (°C)
Cathode Current
vs.
Cathode Voltage
150
100
50
20
0
10
-50
-100
-1
-0.5
0
0.5
1
1.5
0
-10
-1
50
40
30
Cathode Current
vs.
Cathode Voltage
Cathode Current (mA)
0.5
1
1.5
Cathode Voltage (V)
Cathode Voltage (V)
Doc. No. 4006, Rev. J
4
CAT431L
TYPICAL PERFORMANCE CHARACTERISTICS
Off-State Cathode Current
vs.
Junction Temperature
Off-State Cathode Current (nA)
80
0
Delta Reference Voltage Per
Delta Cathode Voltage vs.
Junction Temperature
Delta Reference Voltage per
Delta Cathode Voltage (mV/V)
-0.02
-0.04
-0.06
-0.08
-0.10
-0.12
-0.14
-0.16
-0.18
-50
-25
0
25
50
75
100 125 150
70
60
50
40
30
20
10
0
-50
-25
0
25
50
75
100 125 150
Junction Temperature (°C)
Junction Temperature (°C)
Open Loop Voltage Gain
vs.
Frequency
100
80
100
Dynamic Impedance
vs.
Frequency
Open Loop Voltage Gain (dB)
60
40
20
0
-20
0.001
Dynamic Impedance (kohms)
10
1
0.1
0.01
0.1
1
10
100
1000
0.1
1
10
100
1000
10000
Frequency (kHz)
Frequency (kHz)
5
Doc. No. 4006, Rev. J
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