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 two 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
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°C to +125°C
Reference Voltage Tolerance at +25°C
ZXRE250A: 2.495V ± 1.0%
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
Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
SOT25
ZXRE252
(Top View)
3
ANODE
1
2
REF
CATHODE
Applications
Opto-Coupler Linearisers
Shunt Regulators
Improved Zener
Variable Reference
SOT23
Notes:
1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.
2. See http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green"
and Lead-free.
3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.
ZXRE250/ ZXRE252
Document number: DS35228 Rev. 6 - 2
1 of 12
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May 2017
© Diodes Incorporated
ZXRE250/ ZXRE252
Absolute Maximum Ratings
(Note 4) (@T
A
= +25°C, unless otherwise specified.)
Symbol
V
KA
I
KA
I
REF
T
J
T
ST
P
D
Notes:
Parameter
Cathode Voltage
Continuous Cathode Current
Reference Input Current
Operating Junction Temperature
Storage Temperature
Power Dissipation (Notes 5 & 6)
SOT23
SOT25
Rating
40
150
-0.050 to +10
+150
-55 to +150
330
500
Unit
V
mA
mA
°C
°C
mW
mW
4. 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.
5. T
J
, max = +150°C
6. Ratings apply to ambient temperature at +25°C.
Recommended Operating Conditions
(@T
A
= +25°C, unless otherwise specified.)
Symbol
V
KA
I
KA
T
A
Parameter
Cathode Voltage
Cathode Current
Operating Ambient Temperature
Min
V
REF
0.065
-40
Max
36
100
+125
Unit
V
mA
°C
Electrical Characteristics
Symbol
V
REF
Reference Voltage
(@T
A
= +25°C, unless otherwise specified.)
Test Conditions
V
KA
= V
REF
,
I
KA
= 10mA
ZXRE250A
ZXRE250B
T
A
= 0 to +70°C
T
A
= -40 to +85°C
T
A
= -40 to +125°C
V
KA
= 10V to V
REF
V
KA
= 36V to 10V
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
°C/W
°C/W
Parameter
V
DEV
ΔV
REF
ΔV
KA
I
REF
ΔI
REF
I
KA(MIN)
I
KA(OFF)
Z
KA
θ
JA
Notes:
Deviation of Reference Voltage Over Full V
KA
= V
REF
,
Temperature Range (Note 7)
I
KA
= 10mA
Ratio of the Change in Reference
Voltage to the Change in Cathode
Voltage
Reference Input Current
I
KA
= 10mA
I
KA
= 10mA, R1 = 10KΩ, R2 = ∞
T
A
= 0 to +70°C
I
REF
Deviation Over Full Temperature
I
KA
= 10mA, R1 =
T
A
= -40 to +85°C
Range (Note 7)
10KΩ, R2 = ∞
T
A
= -40 to +125°C
Minimum Cathode Current for Regulation V
KA
= V
REF
Off-State Current
V
KA
= 36V, V
REF
= 0V
Dynamic Output Impedance (Note 8)
Thermal Resistance Junction to Ambient
V
KA
= V
REF,
f = 0Hz
SOT23
SOT25
7. Deviation of V
DEV
, and ΔI
REF
are defined as the maximum variation of the values over the full temperature range.
8. Derivation of Z
KA
on following page.
ZXRE250/ ZXRE252
Document number: DS35228 Rev. 6 - 2
2 of 12
www.diodes.com
May 2017
© Diodes Incorporated
ZXRE250/ ZXRE252
Electrical Characteristics
(cont.) (@T
A
= +25°C, unless otherwise specified.)
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.
Note: 8. 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
Test Circuits
Figure 2 Test Circuit for V
KA
> V
REF
Figure 1 Test Circuit for V
KA
= V
REF
Figure 3 Test Circuit for I
OFF
ZXRE250/ ZXRE252
Document number: DS35228 Rev. 6 - 2
3 of 12
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May 2017
© Diodes Incorporated
ZXRE250/ ZXRE252
Typical Performance Characteristics
2600
2580
V
REF
Reference Voltage (mV)
I
KA
= 10mA
V
KA
= V
REF
T
A
= 25
C
0.2
R1 = 10K
R2 =
I
KA
= 10mA
I
REF
Reference Current (
A)
2560
2540
0.15
2520
2500
2480
2460
2440
2420
0.1
0.05
2400
-55 -35
5
-15
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 (
A)
100
I
KMIN
50
0
0
-50
-100
-2
0
1
2
V
KA
Cathode Voltage (V)
Cathode Current vs. Cathode Voltage
-1
V
KA
= 36V
V
REF
= 0
3
-100
-2
0
1
2
V
KA
Cathode Voltage
Cathode Current vs. Cathode Voltage
-1
3
0.50
0.45
I
KOFF
Off-State Cathode Current (
A)
-0.2
V
KA
= 3V to 36V
-0.3
-0.4
0.40
dV
REF
/dV
KA
(mV/V)
0.35
-0.5
-0.6
0.30
0.25
0.20
0.15
0.10
0.05
-0.7
-0.8
-0.9
-1.0
-50
0.00
-75
75
-25
0
25
50
100 125
T
A
Free Air Temperature (
C)
Off-State Cathode Current vs. Free Air Temperature
-50
75
0
25
50
100 125
T
A
Free Air Temperature (C)
Ratio of Delta Reference Voltage to Delta Cathode
Voltage vs. Free Air Temperature
-25
ZXRE250/ ZXRE252
Document number: DS35228 Rev. 6 - 2
4 of 12
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May 2017
© Diodes Incorporated
ZXRE250/ ZXRE252
Typical Performance Characteristics
(Continued)
400
15
I
KA
= 10mA
V
N
= Equivalent Input Noise Voltage nV/
Hz
Vn - Equivalent Input Noise Voltage -
V
380
V
KA
= V
REF
T
A
= 25°C
360
340
10
I
KA
= 10mA
V
KA
= V
REF
T
A
= 25
C
5
320
300
280
260
240
0
-5
-10
220
200
10
1K
10K
100K
f- Frequency (Hz)
Equivalent Input Noise Voltage vs. Frequency
100
-15
0
4
5
6
7
8
9 10
Time (Seconds)
Equivalent Input Noise Voltage Over A 10-S Period
1
2
3
Figure 4 Test Circuit for Noise Input Voltage
ZXRE250/ ZXRE252
Document number: DS35228 Rev. 6 - 2
5 of 12
www.diodes.com
May 2017
© Diodes Incorporated
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