ZXRE250/ZXRE252
VERY LOW CATHODE CURRENT ADJUSTABLE
PRECISION SHUNT REGULATOR
ZXRE250/ZXRE252
Document number: DS35228 Rev. 3 - 2 1 of 14
www.diodes.com May 2011
© Diodes Inc orporated
NEW PRODUCT
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 po wer 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.
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: VREF to 36V
• SOT23 and SOT25: Available in “Green” Molding
Compound (No Br, Sb) and Lead Free Fin ish/ RoHS
Compliant (Note 1)
Applications
• Opto-Coupler Linearisers
• Shunt Regulators
• Improved Zener
• Variable Reference
Pin Assignments
ZXRE250
ZXRE252
Notes: 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.
A
NODE
CATHODE
3REF
SOT23
(Top View)
2
1
A
NODE
CATHODE
3REF
SOT23
(Top View)
2
1
NC ANODE
CATHODE
5
REF
SOT25
(Top View)
4
2
3
1
Leav e floating or
con nect to pin 5
NC ANODE
CATHODE
5
REF
SOT25
(Top View)
4
2
3
1
Leav e floating or
con nect to pin 5
A
NODE
CATHODE
3
REF
SOT23
(Top View)
2
1
A
NODE
CATHODE
3
REF
SOT23
(Top View)
2
1
ZXRE250/ZXRE252
VERY LOW CATHODE CURRENT ADJUSTABLE
PRECISION SHUNT REGULATOR
ZXRE250/ZXRE252
Document number: DS35228 Rev. 3 - 2 2 of 14
www.diodes.com May 2011
© Diodes Inc orporated
NEW PRODUCT
Absolute Maximum Ratings (Note 2)
Symbol Parameter Rating Unit
VKA Cathode Voltage 40 V
IKA Continuous Cathode Current 150 mA
IREF Reference Input Current -0.050 to +10 mA
TJ Operating Junction Temperature +150 °C
TST Storage Temperature -55 to +150 °C
PD Power Dissipation (Notes 3, 4) SOT23 330 mW
SOT25 500 mW
Notes: 2. Op erati o n above the a bsolute maximum rating may cause device failure. Ope rati on at th e absolute m aximum ratings, for extended periods, may
reduce device reliability. Unless otherwise stated voltages specified are relative to the ANODE pin.
3. TJ, max =150°C.
4. Ratings apply to ambient temperature at 25°C.
Recommended Operating Conditions
Symbol Parameter Min Max Unit
VKA Cathode Voltage VREF 36 V
IKA Cathode Current 0.065 100 mA
TA Operating Ambient Temperature -40 125 °C
ZXRE250/ZXRE252
VERY LOW CATHODE CURRENT ADJUSTABLE
PRECISION SHUNT REGULATOR
ZXRE250/ZXRE252
Document number: DS35228 Rev. 3 - 2 3 of 14
www.diodes.com May 2011
© Diodes Inc orporated
NEW PRODUCT
Electrical Characteristics (TA = +25°C, unless otherwise noted )
Symbol Parameter Test Conditions Min Typ. Max Unit
VREF Reference voltage VKA = VREF,
IKA = 10mA ZXRE250A 2.470 2.495 2.520 V
ZXRE250B 2.482 2.495 2.507 V
VDEV Deviation of reference volta ge over
full temperature range (Note 5) VKA = VREF,
IKA = 10mA
T
A
= 0 to 70 oC 6 16 mV
T
A
= -40 to 85 oC 14 34 mV
T
A
= -40 to 125 oC 14 34 mV
ΔVREF
ΔVKA Ratio of the change in reference
voltage to the change in cathode
voltage IKA = 10mA VK
A
= 10V to VREF -1.4 -2.7 mV/V
VKA = 36V to 10V -1 -2 mV/V
IREF Reference input current IKA = 10mA, R1 = 10KΩ, R2 = ∞ 1 4 μA
ΔIREF IREF deviation over full temperature
range (Note 5) IKA = 10mA, R1
= 10KΩ, R2 = ∞
T
A
= 0 to 70 oC 0.8 1.2 μA
T
A
= -40 to 85 oC 0.8 2.5 μA
T
A
= -40 to 125 oC 0.8 2.5 μA
IKA(MIN) Minimum cathode current for
regulation VKA = VREF 40 65 μA
IKA
(
OFF
)
Off-state current VK
A
= 36V, VREF = 0V 0.05 0.5 μA
|ZKA| Dynamic output impedance (Note 6) VK
A
= VREF
,
f = 0Hz 0.2 0.5 Ω
θJA Thermal Resistance Junction to
Ambient SOT23 380
oC/W
SOT25 250
oC/W
Notes: 5. Deviation of VDEV, and ΔIREF are defined as the maximum variation of the values over the full temperature range.
The average temperature coefficient of the reference input voltage αVREF is defined as:
Where:
T2 – T1 = full temperature change.
αVREF can be positive or negative depending on whether the slope is
positive or negative.
Notes: 6. The dynamic output impedance, RZ, is defined as:
When the device is programmed with two external resistors R1 and R2, the dynamic output
impedance of the overall circuit, is defined as:
=T2 – T1
αV
REF
V
DEV
V
REF
@ 25ºC X 10
6
ppm/ºC
=T2 – T1
αV
REF
V
DEV
V
REF
@ 25ºC X 10
6
ppm/ºC
Vmax
Vmin
T1 T2
V
DEV
= Vmax - Vmin
Temperature
Vmax
Vmin
T1 T2
V
DEV
= Vmax - Vmin
Temperature
=
Z
KA
ΔV
KA
ΔI
KA
=
Z
KA
ΔV
KA
ΔI
KA
=
Z’ ΔV
ΔIZ
KA
1 + R1
R2
≈
=
Z’ ΔV
ΔI
=
Z’ ΔV
ΔIZ
KA
1 + R1
R2
Z
KA
1 + R1
R2
≈
ZXRE250/ZXRE252
VERY LOW CATHODE CURRENT ADJUSTABLE
PRECISION SHUNT REGULATOR
ZXRE250/ZXRE252
Document number: DS35228 Rev. 3 - 2 4 of 14
www.diodes.com May 2011
© Diodes Inc orporated
NEW PRODUCT
Test Circuits
Figure 1. Test circuit for VKA = VREF
Figure 2. Test circuit for VKA > VREF
Figure 3. Test circuit for IOFF
ZXRE250/ZXRE252
VERY LOW CATHODE CURRENT ADJUSTABLE
PRECISION SHUNT REGULATOR
ZXRE250/ZXRE252
Document number: DS35228 Rev. 3 - 2 5 of 14
www.diodes.com May 2011
© Diodes Inc orporated
NEW PRODUCT
Typical Performance Characteristics
2400
2420
2440
2460
2480
2500
2520
2540
2560
2580
2600
-55 -35 -15 5 25 45 65 85 105 125
T Free Air Temperature ( C)
Reference Voltage vs. Free Air Temperature
A
°
V Reference Voltage (mV)
REF
I = 10mA
V = V
T = 25C
KA
KA REF
A
°
0
0.05
0.1
0.15
0.
2
-55 -35 -15 5 25 45 65 85 105 125
T Free Air Temperature ( C)
Reference Current vs. Free Air Temperature
A°
I Reference Cur rent ( A)
REF
μ
R1 = 10K
R2 =
I = 10mA
Ω
∞
KA
-100
-50
0
50
100
150
-2 -1 0123
V Cathode Voltage (V)
Cathode Current vs. Cathode Voltage
KA
I Cathode Current (mA)
KA
V = V
T = 25C
KA REF
A°
-100
0
100
200
-2 -1 0123
V Cathode Voltage
Cathode Current vs. Cathode Voltage
KA
I
KMIN
I Cathode Current ( A)
KA
μ
V = V
T = 25C
KA REF
A
°
ZXRE250/ZXRE252
VERY LOW CATHODE CURRENT ADJUSTABLE
PRECISION SHUNT REGULATOR
ZXRE250/ZXRE252
Document number: DS35228 Rev. 3 - 2 6 of 14
www.diodes.com May 2011
© Diodes Inc orporated
NEW PRODUCT
Typical Performance Characteristics (cont.)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
-75 -50 -25 0 25 50 75 100 125
T Free Air Temperature ( C)
Off-State Cathode Current vs. Free Air Temperature
A
°
I Off-State Cathode Current ( A)
KOFF
μ
V = 36V
V= 0
KA
REF
-1.0
-0.9
-0.8
-0.7
-0.6
-0.5
-0.4
-0.3
-0.
2
-50 -25 0 25 50 75 100 125
V = 3V to 36V
KA
T Free Air Temperature (C)
Ratio of Delta Reference Voltage to Delta Cathode
Voltage vs. Free Air Temperature
A
dV /dV (mV/V)
REF KA
200
220
240
260
280
300
320
340
360
380
400
10 100 1K 10K 100K
f- Frequency (Hz)
Equivalent Input Noise Voltage vs. Frequency
V = Equivalent Input Noise Voltage nV/ Hz
N
√
I = 10mA
V = V
T = 25°C
KA
KA REF
A
ZXRE250/ZXRE252
VERY LOW CATHODE CURRENT ADJUSTABLE
PRECISION SHUNT REGULATOR
ZXRE250/ZXRE252
Document number: DS35228 Rev. 3 - 2 7 of 14
www.diodes.com May 2011
© Diodes Inc orporated
NEW PRODUCT
Typical Performance Characteristics (cont.)
-15
-10
-5
0
5
10
1
5
012345678910
Time (Seconds)
Equivalent Input Noise Voltage Over A 10-S Period
Vn - Equi valent Input Noise Voltage - Vμ
I = 10mA
V = V
T = 25C
KA
KA REF
A
°
Figure 4. Test circuit for noise input voltage
ZXRE250/ZXRE252
VERY LOW CATHODE CURRENT ADJUSTABLE
PRECISION SHUNT REGULATOR
ZXRE250/ZXRE252
Document number: DS35228 Rev. 3 - 2 8 of 14
www.diodes.com May 2011
© Diodes Inc orporated
NEW PRODUCT
Typical Performance Characteristics (cont.)
0
10
20
30
40
50
60
70
100 1K 10K 100K 1M 10M
f Frequency (Hz)
Small-Signal V oltage Amplification vs. Frequency
A Small-Signal Voltage Amplification (dB)
V
I = 10m A
T = 25C
KA
A
°
Test circuit for voltage amplification
0.0
0.1
1.0
10.0
100.0
1K 10K 100K 1M 10M
Z Re ferenc e Impe dance ( )
KA
Ω
I = 10mA
T = 25C
KA
A°
f Frequency (Hz)
Referenc e Impedance vs. Frequency
Test circuit for reference impedance
ZXRE250/ZXRE252
VERY LOW CATHODE CURRENT ADJUSTABLE
PRECISION SHUNT REGULATOR
ZXRE250/ZXRE252
Document number: DS35228 Rev. 3 - 2 9 of 14
www.diodes.com May 2011
© Diodes Inc orporated
NEW PRODUCT
Typical Performance Characteristics (cont.)
0
1
2
3
4
5
6
01 2 345678910
t Time ( s)
Pulse Response
μ
Input and Output Voltage (V)
Output
Input T = 25C
A
°
Test Circuit for Pulse Response
0
10
20
30
40
50
60
70
80
90
100
0.00001 0.0001 0.001 0.01 0.1 1
D
C -Load Capacitance - uF
Stability Boundary Conditions
L
I - Cathode Current - mA
KA
A V = V
B V = 5V
C V = 10V
D V = 15V
KA REF
KA
KA
KA
Stable
Stable Stable
D
CCB
B
A
10
T = 25C
A
°
Test Circuit for Curve A
Test circuit for curves B, C, D
Test Circuit for Curves B, C, D
The device is stable under all conditions with a load capacitance not exceeding 50pF. The device is stable under all conditions with a load
capacitance between 5nF and 20nF. The device is stable under all conditions with a load capacitance exceeding 300nF. With a cathode
current not exceeding 5mA, the device is stable with any load capacitance.
ZXRE250/ZXRE252
VERY LOW CATHODE CURRENT ADJUSTABLE
PRECISION SHUNT REGULATOR
ZXRE250/ZXRE252
Document number: DS35228 Rev. 3 - 2 10 of 14
www.diodes.com May 2011
© Diodes Inc orporated
NEW PRODUCT
Applications Information
Series Regulator
Outp ut Contro l of a Three
Terminal Fixed Regulator
Single Supply Co mpara tor
with Tem perature
Compensated Th reshold Over Voltage / Und er
Vo ltage Prot ection Circuit
Higher Current
Shunt Regulator
Shunt Regulator
ZXRE250/ZXRE252
VERY LOW CATHODE CURRENT ADJUSTABLE
PRECISION SHUNT REGULATOR
ZXRE250/ZXRE252
Document number: DS35228 Rev. 3 - 2 11 of 14
www.diodes.com May 2011
© Diodes Inc orporated
NEW PRODUCT
Orderi ng Information
Device
(Note 7) Package
Code Packaging
(Note 5)
7” Tape and Reel Ammo Box
Quantity Part Number
Suffix Quantity Part Number
Suffix
ZXRE250A(B)SA-7 SA SOT23 3000/Tape & Reel -7 NA NA
ZXRE250A(B)W5-7 W5 SOT25 3000/Tape & Reel -7 NA NA
ZXRE252A(B)SA-7 SA SOT23 3000/Tape & Reel -7 NA NA
Notes: 7. Pad layout as shown on Diodes Inc. suggest e d pad layout document AP02001, which can be found on our website at
http://www.diodes.com/datasheets/ap02001.pdf.
8. Suffix (B) denotes ZXRE250B (0.5% tolerance) device.
Pinout variation Tolerance Package Packing
0: Standard pinout
2: Reversed pinout in SOT23 A: ±1.0%
B: ±0.5% SA: SOT23
W5: SOT25 7: Tape & Reel
ZXRE25 X XXX -7
Pinout variation Tolerance Package Packing
0: Standard pinout
2: Reversed pinout in SOT23 A: ±1.0%
B: ±0.5% SA: SOT23
W5: SOT25 7: Tape & Reel
ZXRE25 X XXX -7
ZXRE250/ZXRE252
VERY LOW CATHODE CURRENT ADJUSTABLE
PRECISION SHUNT REGULATOR
ZXRE250/ZXRE252
Document number: DS35228 Rev. 3 - 2 12 of 14
www.diodes.com May 2011
© Diodes Inc orporated
NEW PRODUCT
Marking Information
(1) SOT23
1 2
3
XX Y W X
( Top View )
XX : Identification code
W : Week : A~Z : 1~26 week;
X : A~Z : Green
Y : Year 0~9
a~z : 27~52 week; z represents
52 and 53 week
Device Package Identification Code
ZXRE250ASA SOT23 DA
ZXRE250BSA SOT23 DB
ZXRE252ASA SOT23 FA
ZXRE252BSA SOT23 FB
(2) SOT25
1 2 3
5
7
4
XX YW X
( Top View )
XX : Identification code
W : Week : A~Z : 1~26 week;
X : A~Z : G r een
Y : Year 0~9
a~z : 27~52 week; z represents
52 and 53 week
Device Package Identification Code
ZXRE250AW5 SOT25 DA
ZXRE250BW5 SOT25 DB
ZXRE250/ZXRE252
VERY LOW CATHODE CURRENT ADJUSTABLE
PRECISION SHUNT REGULATOR
ZXRE250/ZXRE252
Document number: DS35228 Rev. 3 - 2 14 of 14
www.diodes.com May 2011
© Diodes Inc orporated
NEW PRODUCT
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DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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the express written app roval of t he Chief Executive Off icer of Diodes Incorporated. As used herein:
A. Life support device s or syst ems are devices or systems which:
1. are intend ed t o impl ant into the body, or
2. support or sustain life and whose failure to perform when properly used in accordance with i nstructions for use provided
in the labeling can be reasonably expected to result in significant in jury to t he user.
B. A critical com ponent is any component in a life support device or syst em whose failure to perform can be reasonably expected
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