ZXRE250/ZXRE252
VERY LOW CATHODE CURRENT ADJUSTABLE
PRECISION SHUNT REGULATOR
Description
The ZXRE250 and ZXRE252 are three terminal adjustable
shunt regulators offering excellent temperature stability and
output current handling capability up to 100mA. The output
voltage may be set to any chosen voltage between 2.5 and
36 volts by selection of two external divider resistors.
ZXRE250 has the same electrical specifications as the
industry standard ‘431 except that it features a very low
minimum cathode current for regulation. The typical value of
40µA makes the parts ideal for very low power applications.
The devices can be used as a replacement for zener diodes
in many applications requiring an improvement in zener
performance. The ZXRE250/2 is available in 2 grades with
initial tolerances of 1% and 0.5% for the A and B grades
respectively.
Pin Assignments
ZXRE250
(Top View)
3
ANODE
1
2
CATHODE
REF
NEW PRODUCT
SOT23
(Top View)
NC
Leave floating or
connect to pin 5
CATHODE
1
2
3
4 REF
5
ANODE
Features
•
•
•
Minimum cathode current for regulation: 40μA (typ)
Temperature range -40 to 125ºC
Reference Voltage Tolerance at 25°C
o
ZXRE250A: 2.495V
±
1.0%.
o
ZXRE250B: 2.495V
±
0.5%
Low Output Noise
0.2Ω Typical Output Impedance
Sink Current Capability: 0.065mA to 100mA
Adjustable Output Voltage: V
REF
to 36V
SOT23 and SOT25: Available in “Green” Molding
Compound (No Br, Sb) and Lead Free Finish/ RoHS
Compliant (Note 1)
SOT25
ZXRE252
(Top View)
3
ANODE
1
2
REF
CATHODE
•
•
•
•
•
SOT23
Applications
•
•
•
•
Opto-Coupler Linearisers
Shunt Regulators
Improved Zener
Variable Reference
1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at
http://www.diodes.com/products/lead_free.html.
Notes:
ZXRE250/ZXRE252
Document number: DS35228 Rev. 3 - 2
1 of 14
www.diodes.com
May 2011
© Diodes Incorporated
ZXRE250/ZXRE252
VERY LOW CATHODE CURRENT ADJUSTABLE
PRECISION SHUNT REGULATOR
Absolute Maximum Ratings
(Note 2)
Symbol
V
KA
I
KA
I
REF
T
J
T
ST
Cathode Voltage
Continuous Cathode Current
Reference Input Current
Operating Junction Temperature
Storage Temperature
Power Dissipation (Notes 3, 4)
SOT23
SOT25
Parameter
Rating
40
150
-0.050 to +10
+150
-55 to +150
330
500
Unit
V
mA
mA
°
°
C
C
NEW PRODUCT
P
D
Notes:
mW
mW
2. Operation above the absolute maximum rating may cause device failure. Operation at the absolute maximum ratings, for extended periods, may
reduce device reliability. Unless otherwise stated voltages specified are relative to the ANODE pin.
3. T
J
, max =150°C.
4. Ratings apply to ambient temperature at 25°C.
Recommended Operating Conditions
Symbol
V
KA
I
KA
T
A
Cathode Voltage
Cathode Current
Operating Ambient Temperature
Parameter
Min
V
REF
0.065
-40
Max
36
100
125
Unit
V
mA
°C
ZXRE250/ZXRE252
Document number: DS35228 Rev. 3 - 2
2 of 14
www.diodes.com
May 2011
© Diodes Incorporated
ZXRE250/ZXRE252
VERY LOW CATHODE CURRENT ADJUSTABLE
PRECISION SHUNT REGULATOR
Electrical Characteristics
(T
A
= +25°C, unless otherwise noted)
Symbol
V
REF
Parameter
Reference voltage
Deviation of reference voltage over
full temperature range (Note 5)
Ratio of the change in reference
voltage to the change in cathode
voltage
Reference input current
I
REF
deviation over full temperature
range (Note 5)
Minimum cathode current for
regulation
Off-state current
Dynamic output impedance (Note 6)
Thermal Resistance Junction to
Ambient
Test Conditions
ZXRE250A
V
KA
= V
REF
,
I
KA
= 10mA
ZXRE250B
T
A
= 0 to 70
o
C
V
KA
= V
REF
,
T
A
= -40 to 85
o
C
I
KA
= 10mA
T
A
= -40 to 125
o
C
V
KA
= 10V to V
REF
I
KA
= 10mA
V
KA
= 36V to 10V
I
KA
= 10mA, R1 = 10KΩ, R2 =
∞
o
T
A
= 0 to 70 C
I
KA
= 10mA, R1
T
A
= -40 to 85
o
C
= 10KΩ, R2 =
∞
T
A
= -40 to 125
o
C
V
KA
= V
REF
V
KA
= 36V, V
REF
= 0V
V
KA
= V
REF,
f = 0Hz
SOT23
SOT25
Min
2.470
2.482
Typ.
2.495
2.495
6
14
14
-1.4
-1
1
0.8
0.8
0.8
40
0.05
0.2
380
250
Max
2.520
2.507
16
34
34
-2.7
-2
4
1.2
2.5
2.5
65
0.5
0.5
Unit
V
V
mV
mV
mV
mV/V
mV/V
μA
μA
μA
μA
μA
μA
Ω
o
C/W
o
C/W
V
DEV
ΔV
REF
ΔV
KA
I
REF
ΔI
REF
NEW PRODUCT
I
KA(MIN)
I
KA(OFF)
|Z
KA
|
θ
JA
Notes:
5. Deviation of V
DEV
, and
ΔI
REF
are defined as the maximum variation of the values over the full temperature range.
The average temperature coefficient of the reference input voltage
αV
REF
is defined as:
Vmax
V
DEV
αV
REF
=
V
REF
@ 25ºC
T2 – T1
X 10
6
ppm/ºC
Vmin
Where:
T2 – T1 = full temperature change.
αV
REF
can be positive or negative depending on whether the slope is
positive or negative.
Notes: 6. The dynamic output impedance, R
Z
, is defined as:
V
DEV
= Vmax - Vmin
Z
KA
=
ΔV
KA
ΔI
KA
T1
Temperature
T2
When the device is programmed with two external resistors R1 and R2, the dynamic output
impedance of the overall circuit, is defined as:
Z’ =
ΔV
ΔI
≈
Z
KA
1+
R1
R2
ZXRE250/ZXRE252
Document number: DS35228 Rev. 3 - 2
3 of 14
www.diodes.com
May 2011
© Diodes Incorporated
ZXRE250/ZXRE252
VERY LOW CATHODE CURRENT ADJUSTABLE
PRECISION SHUNT REGULATOR
Test Circuits
NEW PRODUCT
Figure 1. Test circuit for V
KA
= V
REF
Figure 2. Test circuit for V
KA
> V
REF
Figure 3. Test circuit for I
OFF
ZXRE250/ZXRE252
Document number: DS35228 Rev. 3 - 2
4 of 14
www.diodes.com
May 2011
© Diodes Incorporated
ZXRE250/ZXRE252
VERY LOW CATHODE CURRENT ADJUSTABLE
PRECISION SHUNT REGULATOR
Typical Performance Characteristics
2600
2580
I
KA
= 10mA
V
KA
= V
REF
T
A
= 25
°
C
0.2
R1 = 10K
Ω
R2 =
∞
I
KA
= 10mA
V
REF
Reference Voltage (mV)
I
REF
Reference Current (
μ
A)
2560
2540
2520
2500
2480
2460
2440
2420
2400
-55 -35
0.15
NEW PRODUCT
0.1
0.05
-15
5
25 45
65 85 105 125
T
A
Free Air Temperature (
°
C)
Reference Voltage vs. Free Air Temperature
0
-55
-15
5
25 45 65
85 105 125
T
A
Free Air Temperature (
°
C)
Reference Current vs. Free Air Temperature
-35
150
V
KA
= V
REF
T
A
= 25
°
C
200
V
KA
= V
REF
T
A
= 25
°
C
100
I
KA
Cathode Current (mA)
I
KA
Cathode Current (
μ
A)
100
I
KMIN
50
0
0
-50
-100
-2
0
1
2
V
KA
Cathode Voltage (V)
Cathode Current vs. Cathode Voltage
-1
3
-100
-2
0
1
2
V
KA
Cathode Voltage
Cathode Current vs. Cathode Voltage
-1
3
ZXRE250/ZXRE252
Document number: DS35228 Rev. 3 - 2
5 of 14
www.diodes.com
May 2011
© Diodes Incorporated
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