LX432
L
OW
V
OLTAGE
A
DJUSTABLE
P
RECISION
S
HUNT
R
EGULATORS
T
H E
I
N F I N I T E
P
O W E R
O F
I
N N O VA T I O N
P
R O D U C T I O N
D
A T A
S
H E E T
DESCRIPTION
The LX432 series are low-voltage pre-
cision adjustable shunt regulators
with a reference voltage of 1.24V. The
output voltage may be set to any value
between 1.24V and 20V by two external
resistors.
These devices offer low output im-
pedance for improved load regula-
tion
— typical output impedance is
250mΩ. The LX432 series operates with
an operating current as low as 80µA,
making these devices suitable for por-
table and micropower applications.
Low voltage operation enables the
LX432 to be used in the feedback loop
of isolated low voltage power sup-
plies.
The minimum output voltage is
determined by the LX432 output voltage
plus the forward voltage drop of the
opto-coupler LED (typically 1.24 + 1.4 =
2.64V minimum). See Figure 10.
The LX432 is offered in 3 and 5-pin
SOT-23 or TO-92 packages, and is a drop-
in replacement for the TLV431 and
SC431L devices.
s
s
s
s
K E Y F E AT U R E S
Low Voltage Operation: 1.24V Reference
Initial Voltage Reference Accuracy 1%
Adjustable Output Voltage From V
REF
To 20V
Typical Output Dynamic Impedance Less
Than 250mΩ
s
Sink Current Capability 80µA To 20mA
s
Direct Alternative To TLV431
A P P L I C AT I O N S
s
s
s
s
Low Voltage Adjustable Power Supplies
Instrumentation
Computers
Portable Equipment
IMPORTANT:
For the most current data, consult LinFinity's web site:
http://www.linfinity.com.
PRODUCT HIGHLIGHT
T
Y P I C A L
P
R O G R A M M A B L E
V
O LTA G E
R
EFERENCE
C
IRCUIT
V
IN
Cathode
V
KA
R1
Reference
LX432
Anode
R2
GND
PA C K A G E O R D E R I N F O R M AT I O N
T
A
(°C)
0 to 70
-40 to 85
SC
Plastic SOT-23
3-pin
LX432CSC
LX432ISC
SE
Plastic SOT-23
5-pin
LX432CSE
LX432ISE
LP
Plastic TO-92
3-pin
LX432CLP
LX432ILP
Note: All surface-mount packages are available in Tape & Reel.
Append the letter "T" to part number. (i.e. LX432CSET)
TO-92 (LP) package also available in ammo-pack.
Copyright © 1999
Rev. 1.0 9/99
L
IN
F
INITY
M
ICROELECTRONICS
I
NC
.
11861 W
ESTERN
A
VENUE
, G
ARDEN
G
ROVE
, CA. 92841, 714-898-8121, F
AX
: 714-893-2570
1
PRODUCT DATABOOK 1996/1997
LX432
L
OW
V
OLTAGE
A
DJUSTABLE
P
RECISION
S
HUNT
R
EGULATORS
P
R O D U C T I O N
D
A T A
S
H E E T
A B S O L U T E M A X I M U M R AT I N G S
(Note 1)
PACKAGE PIN OUTS
Cathode to Anode Voltage (V
KA
) ................................................................. -0.3V to +20V
Reference Input Current (I
REF
) .................................................................... -50µA to 10µA
Continuous Cathode Current (I
K
) ............................................................. -25mA to 25mA
Operating Junction Temperature
Plastic (SC, SE & LP Packages) ............................................................................. 150°C
Storage Temperature Range ...................................................................... -65°C to 150°C
Lead Temperature ..................................................................................................... 300°C
Note 1. Exceeding these ratings could cause damage to the device. All voltages are with respect
to Ground. Currents are positive into, negative out of the specified terminal. Pin
numbers refer to DIL packages only.
2
CATHODE
ANODE
3
1
REF
SC PACKAGE — 3-Pin
(Top View)
T H E R M A L D ATA
SC PACKAGE:
Thermal Resistance - Junction to Ambient,
θ
JA
SE PACKAGE:
Thermal Resistance - Junction to Ambient,
θ
JA
LP PACKAGE:
Thermal Resistance-Junction to Ambient,
θ
JA
156°C/W
(PC-Mounted)
(Non-PC Mounted)
220°C/W
410°C/W
(PC-Mounted)
(Non-PC Mounted)
220°C/W
410°C/W
N.C.
N.C.
CATHODE
1
2
3
5
ANODE
4
REF
SE PACKAGE — 5-Pin
(Top View)
3.
CATHODE
2.
ANODE
1.
REF
Junction Temperature Calculation: T
J
= T
A
+ (P
D
x
θ
JA
).
The
θ
JA
numbers are guidelines for the thermal performance of the device/pc-board system.
All of the above assume no ambient airflow
BLOCK DIAGRAM
LP PACKAGE
(Top View)
Cathode (K)
Ref (R)
V
REF
Anode (A)
2
Copyright © 1999
Rev. 1.0 9/99
PRODUCT DATABOOK 1996/1997
LX432
L
OW
V
OLTAGE
A
DJUSTABLE
P
RECISION
S
HUNT
R
EGULATORS
P
R O D U C T I O N
D
A T A
S
H E E T
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, these specifications apply over the operating ambient temperatures for LX432C with 0°C
≤
T
A
≤
70°C, and the LX432I
with -40°C
≤
T
A
≤
85°C.)
Parameter
Reference Voltage
Reference Voltage Drift
(Note 2)
Ratio Of V
REF
Change In Cathode
Voltage Change
(Note 3)
Reference Terminal Current
Reference Current Drift
(Note 2)
Minimum Cathode Current For Regulation
Dynamic Impedance
Off-state Cathode Current
∆V
REF
∆V
KA
Symbol
V
REF
∆V
REF
∆V
REF
∆V
KA
I
REF
∆I
REF
I
K (MIN)
Z
KA
I
OFF
Test Conditions
I
K
= 10mA, V
KA
= V
REF
, T
A
= 25°C
I
K
= 10mA, V
KA
= V
REF
, 0°C
≤
T
A
≤
70°C
I
K
= 10mA, V
KA
= V
REF
, -40°C
≤
T
A
≤
85°C
I
K
= 10mA, V
KA
= V
REF
to 16V, T
A
= 25°C
I
K
= 10mA, V
KA
= V
REF
, T
A
= 25°C, R1=10kΩ, R2 = Open
I
K
= 10mA, V
KA
= V
REF
, 0°C
≤
T
A
≤
70°C
I
K
= 10mA, V
KA
= V
REF
, -40°C
≤
T
A
≤
85°C
V
KA
= V
REF
, T
A
= 25°C
I
K
= 0.1mA to 15mA, V
KA
= V
REF
, T
A
= 25°C
V
KA
= 16V, T
A
= 25°C
LX432
Min. Typ. Max.
1.228
1.24
3
4
-1
0.1
0.05
0.1
55
0.2
0.004
1.252
12
20
-2.7
0.5
0.3
0.4
80
0.4
Units
V
mV
mV
mV/V
µA
µA
µA
µA
Ω
µA
Note 2. These parameters are guaranteed by design.
Note 3.
Ratio of change in reference input voltage
to the change in cathode voltage.
Copyright © 1999
Rev. 1.0 9/99
3
PRODUCT DATABOOK 1996/1997
LX432
L
OW
V
OLTAGE
A
DJUSTABLE
P
RECISION
S
HUNT
R
EGULATORS
P
R O D U C T I O N
D
A T A
S
H E E T
GRAPH / CURVE INDEX
FIGURE INDEX
Characteristic Curves
FIGURE #
1.
2.
3.
4.
5.
6.
7.
8.
Reference Voltage vs. Junction Temperature
Reference Current vs. Junction Temperature
Cathode Current vs. Cathode Voltage
∆V
REF
/
∆V
KA
vs. Junction Temperature
Dynamic Impedance vs. Junction Temperature
Minimum Cathode Current For Regulation vs. Junction
Temperature
Off-State Current vs. Junction Temperature
Equivalent Input Noise Voltage vs. Frequency
FIGURE #
FIGURE #
9.
Parameter Measurement Information
Test Circuit For V
KA
= V
REF
10.
Test Circuit For V
KA
> V
REF
11.
Test Circuit For I
OFF
Typical Applications
12.
Flyback With Isolation Using LX431 Or LX431A As Voltage
Reference And Error Amplifier
13.
LX432 In 3.3V To 2.7V Low Dropout Regulator Application
4
Copyright © 1999
Rev. 1.0 9/99
PRODUCT DATABOOK 1996/1997
LX432
L
OW
V
OLTAGE
A
DJUSTABLE
P
RECISION
S
HUNT
R
EGULATORS
P
R O D U C T I O N
D
A T A
S
H E E T
CHARACTERISTIC CURVES
1.25
0.2
V
REF
: Reference Voltage (V)
I
REF
: Reference Current ( A)
0.16
1.245
0.12
1.24
0.08
1.235
0.04
1.23
-40 -30 -20 -10 0
10 20 30 40 50 60 70 80 90
0
-40 -30 -20 -10 0
10 20 30 40 50 60 70 80 90
T
J
: Junction Temperature ( C)
T
J
: Junction Temperature ( C)
FIGURE 1
— Reference Voltage vs. Junction Temperature
FIGURE 2
— Reference Current vs. Junction Temperature
800
700
-1.200
I
K
: Cathode Current ( A)
600
-1.000
400
300
200
100
0
-100
-200
-1
-0.5
0
0.5
1
1.5
∆
V
REF
/
∆
V
KA
(mV/V)
500
-0.800
-0.600
-0.400
-0.200
-40 -30 -20 -10 0
10 20 30 40 50 60 70 80 90
T
J
: Junction Temperature (V)
T
J
: Junction Temperature ( C)
FIGURE 3
— Cathode Current vs. Cathode Voltage
FIGURE 4
—
∆V
REF
/
∆V
KA
vs. Junction Temperature
Copyright © 1999
Rev. 1.0 9/99
5
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