LX6431 / 6431A / 6431B
P
RECISION
P
ROGRAMMABLE
R
EFERENCES
T
H E
I
N F I N I T E
P
O W E R
O F
I
N N O V A 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 LX6431 series precision adjustable three
terminal shunt voltage regulators are pin-to-pin
compatible with the industry standard TL431, but
with significant improvements.
The LX6431
design has eliminated regions of instability
common to older generation shunt regulator
products like the TL431. Designs are made simpler
by eliminating the task of insuring capacitive loads,
and output voltage and cathode currents don’t
combine for unstable operation. The capacitor
value is chose simply to give the best load transient
response without the possibility of instability. A
lower reference input current allows the use of
higher value reference divider resistors, reducing
the current drain from batteries in portable
equipment as well as reducing the voltage
programming errors due to the impedance of the
divider network (See product Highlight)
In addition, the LX6431B has an improved
initial accuracy of 0.4%, and the output voltage is
programmable by using two external resistors
from 2.5V to 36V.
These devices offer low output impedance for
improved load regulation. The typical output
impedance of these devices is 100mΩ. The
reduced reference input bias current and minimum
operating currents make these devices suitable for
portable and micro power applications.
KEY FEATURES
Unconditionally Stable for All
Cathode To Anode Capacitance
Values
Reduced Reference Input
Current Allowing The Use of
Higher Value Divider Resistors
(0.5µA)
Initial Voltage Reference
Accuracy of 0.4% (LX6431B)
Sink Current Capability 0.6mA to
100mA
Typical Output Dynamic
Impedance Less Than 100mΩ
Adjustable Output Voltage From
2.5V to 36V
IMPORTANT:
For the most current data, consult
MICROSEMI’s
website:
http://www.microsemi.com
PRODUCT HIGHLIGHT
Output Voltage Error Due to I
REF
T
A
(°C)
Initial
Tolerance
2%
1%
0.4%
2%
1%
0.4%
PK
PACKAGE ORDER INFO
Plastic TO-89
Plastic SOIC
DM
8-Pin
3-Pin
RoHS Compliant / Pb-free
Transition D/C: 0440
LP
Plastic TO-92
3-Pin
RoHS Compliant / Pb-free
Transition D/C: 0518
RoHS Compliant / Pb-free
Transition D/C: 0509
0 to 70
-40 to 85
LX6431CPK
LX6431ACPK
LX6431BCPK
LX6431IPK
LX6431AIPK
LX6431BIPK
LX6431CDM
LX6431ACDM
LX6431BCDM
LX6431IDM
LX6431AIDM
LX6431BIDM
LX6431CLP
LX6431ACLP
LX6431BCLP
LX6431ILP
LX6431AILP
LX6431BILP
Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX6431CDM-TR)
Copyright
©
1999
Rev. 1.4a,2005-04-04
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
LX6431 / 6431A / 6431B
P
RECISION
P
ROGRAMMABLE
R
EFERENCES
T
H E
I
N F I N I T E
P
O W E R
O F
I
N N O V A T I O N
P
R O D U C T I O N
D
A T A
S
H E E T
ABSOLUTE MAXIMUM RATINGS
Cathode to Anode Voltage (V
KA
).................................................................... -0.3V to 37V
Reference Input Current (I
REF
) .....................................................................-50µA to 10µA
Continuous Cathode Current (I
K
)........................................................... -100mA to 150mA
Operating Temperature Range ................................................................................... 150°C
Maximum Operating Junction Temperature
Plastic (DM & LP Packages) ..................................................................................... 150°C
Storage Temperature Range.........................................................................-65°C to 150°C
Package Peak Temp. for Solder Reflow (40 seconds maximum exposure) ... 260°C (+0 -5)
Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to
Ground. Currents are positive into, negative out of specified terminal
.
Pin numbers refer to DIL packages only.
PACKAGE PIN OUT
CATHODE
N.C.
ANODE
N.C.
1
8
REF
ANODE
ANODE
N.C.
2
7
3
6
4
5
DM P
ACKAGE
(Top View)
1
CATHODE
ANODE
REF
2
3
THERMAL DATA
LP P
ACKAGE
(Top View)
DM
Plastic SOIC 8-Pin
THERMAL RESISTANCE
-
JUNCTION TO
A
MBIENT
,
θ
JA
LP
Plastic TO-92 3-Pin
THERMAL RESISTANCE
-
JUNCTION TO
A
MBIENT
,
θ
JA
Plastic TO-89 3-Pin
THERMALRESISTANCE
-
JUNCTION TO TAB
,
θ
JT
THERMAL RESISTANCE
-
JUNCTION TO
A
MBIENT
,
θ
JA
165°C/W
REF
1
ANODE
2
156°C/W
CATHODE
3
PK
PK P
ACKAGE
35°C/W
71°C/W
(Top View)
N.C. – No Connection
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.
RoHS / Pb-free 100% Matte Tin Lead Finish
SIMPLIFIED BLOCK DIAGRAM
Cathode (K)
REF(R)
+
-
V
REF
Anode (A)
Copyright
©
1999
Rev. 1.4a,2005-04-04
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
2
PRODUCT DATABOOK 1996/1997
LX6431/LX6431A/LX6431B
P
RECISION
P
ROGRAMMABLE
R
EFERENCES
P
R O D U C T I O N
D
A T A
S
H E E T
ELECTRICAL CHARACTERISTICS
(Note 2)
(Unless otherwise specified, these specifications apply over the operating ambient temperatures for LX6431C/LX6431AC/LX6431BC with 0°C
≤
T
A
≤
70°C, LX6431I/LX6431AI/LX6431BI with -40°C
≤
T
A
≤
85°C.)
Parameter
Reference Input Voltage
LX6431
LX6431A
LX6431B
LX6431
LX6431A
LX6431B
Voltage Ratio, Reference to Cathode
(Note 3)
Reference Input Current
Minimum Operating Current
Off-State Cathode Current
Dynamic Impedance
Note 2. These parameters are guaranteed by design.
Note 3.
∆V
REF
∆V
KA
Symbol
V
REF
Test Conditions
I
K
= 10mA, V
KA
= V
REF
, T
A
= 25°C,
I
K
= 10mA, V
KA
= V
REF
, T
A
= 25°C
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
, 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
, 0°C
≤
T
A
≤
70°C
I
K
= 10mA, V
KA
= V
REF
, -40°C
≤
T
A
≤
85°C
I
K
= 10mA, V
KA
= 2.5V to 36V, T
A
= 25°C
I
K
= 10mA, V
KA
= 2.5V to 36V, T
A
= Operating Range
V
KA
= V
REF
, T
A
= 25°C
V
KA
= V
REF
, T
A
= Operating Range
V
KA
= V
REF
to 36V, T
A
= 25°C
V
KA
= V
REF
to 36V, T
A
= Operating Range
V
KA
= 36V, V
REF
= 0V, T
A
= 25°C
V
KA
= V
REF
, I
K
= 0.6mA to 100mA, f
≤
1kHz, T
A
= 25°C
LX6431
Units
Min. Typ. Max.
2440
2470
2490
2550
2520
2510
15
25
15
25
15
20
1
1
0.5
0.5
0.6
0.6
1
100
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV/V
mV/V
µA
µA
mA
mA
µA
mΩ
Reference Drift
I
REF
I
MIN
I
OFF
Z
KA
0.3
0.3
0.1
0.1
0.4
0.4
0.3
30
Ratio of change in reference input voltage
to the change in cathode voltage.
Copyright © 1999
Rev. 1.4a
3
PRODUCT DATABOOK 1996/1997
LX6431/LX6431A/LX6431B
P
RECISION
P
ROGRAMMABLE
R
EFERENCES
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.
REFERENCE VOLTAGE vs. FREE-AIR TEMPERATURE
REFERENCE CURRENT vs. FREE-AIR TEMPERATURE
CATHODE CURRENT vs. CATHODE VOLTAGE
OFF-STATE CATHODE CURRENT vs. FREE-AIR TEMPERATURE
RATIO OF DELTA REFERENCE VOLTAGE TO DELTA CATHODE
VOLTAGE vs. FREE-AIR TEMPERATURE
EQUIVALENT INPUT NOISE VOLTAGE vs. FREQUENCY
FIGURE #
9.
8.
FIGURE #
7.
Application Information
COMPARISON OF REFERENCE RESISTOR VALUES BETWEEN AN
LX6431B AND A TL1431. Resistors used with the LX6431B are 5
times higher in value.
COMPARISON OF REFERENCE RESISTOR VALUES BETWEEN AN
LX6431B AND A TL1431. When used as 0.5%, 5V shunt
regulators.
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 Characteristics
FIGURE #
12.
EQUIVALENT INPUT NOISE VOLTAGE OVER A 10-SECOND PERIOD
13.
SMALL-SIGNAL VOLTAGE AMPLIFICATION vs. FREQUENCY
14.
REFERENCE IMPEDANCE vs. FREQUENCY
15.
PULSE RESPONSE
16.
DIFFERENTIAL VOLTAGE AMPLIFICATION
vs. FREQUENCY
4
Copyright © 1999
Rev. 1.4a
PRODUCT DATABOOK 1996/1997
LX6431/LX6431A/LX6431B
P
RECISION
P
ROGRAMMABLE
R
EFERENCES
P
R O D U C T I O N
D
A T A
S
H E E T
CHARACTERISTIC CURVES
FIGURE 1.
— REFERENCE VOLTAGE
vs. FREE-AIR TEMPERATURE
2.52
FIGURE 2.
— REFERENCE CURRENT
vs. FREE-AIR TEMPERATURE
0.15
(I
REF
) Reference Current - (µA)
(V
REF
) Reference Voltage - (V)
V
REF
= V
KA
I
K
= 10mA
2.51
I
K
= 10mA
R1 = 10kW
0.14
0.13
2.50
0.12
2.49
0.11
2.48
-50
-25
0
25
50
75
100
125
0.1
-50
-25
0
25
50
75
100
125
(T
A
) Ambient Temperature - (°C)
(T
A
) Ambient Temperature - (°C)
FIGURE 3.
— CATHODE CURRENT vs. CATHODE VOLTAGE
800
FIGURE 4.
— OFF-STATE CATHODE CURRENT
vs. FREE-AIR TEMPERATURE
0.8
(I
OFF
) Off-State Cathode Current - (µA)
V
KA
= V
REF
T
A
= 25°C
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-50
V
KA
= 36V
V
REF
= 0
(I
K
) Cathode Current - (µA)
600
400
200
0
-200
-2
-1
0
1
2
3
4
-25
0
25
50
75
100
125
(V
KA
) Cathode Voltage - (V)
(T
A
) Ambient Temperature - (°C)
Copyright © 1999
Rev. 1.4a
5
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