Datenblatt für ZEN50 Guide von Peak Electronic Design Limited

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Atlas ZEN
Zener Diode Analyser
Model ZEN50
Designed and manufactured with pride in the UK
User Guide
©
Peak Electronic Design Limited 2015
In the interests of development, information in this guide is subject to change without notice - E&OE
GB50-02
ZEN50 User Guide September 2015 – Rev 2
Page 2
Want to use it now?
We understand that you want to use your Atlas ZEN right now. The
unit is ready to go and you should have little need to refer to this user
guide, but please make sure that you do at least take a look at the very
important notices on page 4!
Contents Page
Introduction....................................................................................3
Important Considerations...............................................................4
Testing Zeners................................................................................5
Changing Test Currents .................................................................7
Slope Resistance ............................................................................8
Testing LEDs and other diodes (Read warning carefully!) .......10
Test Voltages ...............................................................................11
Loading Limitations.....................................................................12
Care of your Atlas ZEN ...............................................................13
Self Test Procedure ......................................................................14
LCD Contrast Adjustment............................................................14
Appendix A - Technical Specifications........................................15
Appendix B - Warranty Information............................................16
Appendix C - Disposal information .............................................16
gm
ZEN50 User Guide September 2015 – Rev 2
Page 3
Introduction
The Peak Atlas ZEN is an intelligent Zener Diode analyser that offers great
features together with ease of use.
Summary Features:
• Supports the following components:
Zener diodes and Avalanche diodes.
Shunt voltage references.
Conventional diodes and LEDs (for V
F
measurement and slope
resistance measurement). WARNING: Reverse bias testing will
break your LED.
VDRs, TVSs, Transorbs, etc. (up to 50V).
• Selectable test currents: 2mA, 5mA, 10mA and 15mA.
• Measure Zener Voltage (V
Z
).
• Measure Forward voltage drop for forward connected diodes.
• Display of selected test current.
• Measure Slope Resistance (sometimes called dynamic resistance or
differential resistance).
• Advanced voltage boost to support testing up to 50V at 15mA.
• Constant test conditions regardless of battery level (V
BAT
down to 1V).
• Low test duty cycle to minimize Zener power dissipation.
• Continuous measurements (typically 3 samples per second).
• Gold plated crocodile clip probes for low contact resistance.
• LCD contrast adjustment.
• Automatic and manual power-off.
t will
ZEN50 User Guide September 2015 – Rev 2
Page 4
Important Considerations
•
This instrument must NEVER be connected to powered
equipment/components or equipment/components with any
stored energy (e.g. charged capacitors). Failure to comply
with this warning may result in personal injury, damage to
the equipment under test, damage to the Atlas ZEN and
invalidation of the manufacturer’s warranty.
•
The Atlas ZEN is designed to analyse Zeners that are not
in-circuit, complex circuit effects can result in erroneous
measurements. Additionally, testing in-circuit can expose
your circuit to unexpectedly high voltages that may damage
it, YOU HAVE BEEN WARNED.
•
The voltages generated by the Atlas ZEN can damage
non-Zener components (for example, reverse bias testing
LEDs will damage your LEDs). It is your responsibility to
ensure the voltages/currents are suitable for your
component and that they are correctly connected.
•
Avoid rough treatment or hard knocks.
•
This unit is not waterproof.
•
Only use a good quality Alkaline AAA battery.
(mm
ZEN50 User Guide September 2015 – Rev 2
Page 5
Testing Zeners
The Atlas ZEN is primarily designed to analyse Zener diodes (including
Avalanche diodes). Often, Avalanche diodes are referred to as Zener diodes
because they are used in a similar way.
As well as testing Zeners, the Atlas ZEN is great for measuring the conduction
characteristics for many other components types:
Normal diodes (measuring V
F
at various forward currents).
LEDs (measuring V
F
at various forward currents). Do not attempt
to test an LED in reverse, you will break it.
Transient suppressors such as VDRs, TVSs and Transorbs
(measuring the breakdown/clamping voltage at various forward or
reverse currents).
Shunt Voltage Regulators (measuring V
F
at various forward
currents).
A Zener diode is normally used in the reverse biased mode. If you use it in the
forward biased mode then you will see a conventional diode behaviour.
To test a Zener diode, connect it as shown here:
Red
Anode
Cathode
Black
Z
The Atlas ZEN will start its analysis
shortly after the on-test button is
pressed and the start-up screen is shown.
It will then continue to perform regular
measurements and show the results on the LCD screen.
ZEN50 User Guide September 2015 – Rev 2
Page 6
Testing Zeners
continued
The display is updated at a rate of approximately 3 times per second. Please
allow a few seconds for readings to settle however.
The display will show all the key parameters at the same time.
The top line shows the measured voltage across the probes at the selected test
current (10mA in this case). Note that the test current is applied in short pulses,
so the displayed voltage won’t be present across the component continuously.
The bottom line shows the slope resistance of the Zener. This is calculated at
the same nominal test current as the V
Z
measurement and is based on a span of
test currents.
At any time, you can pause (Hold) the displayed values by briefly pressing the
on-test button. This can be useful if you want to remove the component being
tested but still want to see the measurement results. When the unit is in Hold
mode, the following symbol will be displayed:
Although the Atlas ZEN will switch itself off if left unattended, you
can manually switch the unit off by holding down the scroll-off
button for a couple of seconds.
ZEN50 User Guide September 2015 – Rev 2
Page 7
Changing Test Currents
The characteristics of Zeners (and other devices) will change depending on the
current flowing through the component. For Zeners in particular, it is common
to see that the Zener voltage specified by the manufacturer is quoted at a
certain test current. All Zeners will exhibit an increase in the Zener voltage as
test current rises.
You can select different test currents for your device by briefly pressing the
scroll-off button:
Range Test Current
1 2mA
2 5mA
3 10mA
4 15mA
The following graph shows that a typical Zener exhibits the manufacturer’s
stated voltage of 3.3V at 10mA, but rises if the test current is higher.
Example of 3.3V 500mW Zener
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0 0.5 1 1.5 2
2.5
3
“Knee”
3.3 3.5 4
Zener Voltage (V)
Test Current (mA)
Many Zeners, particularly higher voltage ones, will have a sharper “knee” than
this particular example.
ZEN50 User Guide September 2015 – Rev 2
Page 8
Slope Resistance
An ideal Zener diode would yield a constant Zener voltage regardless of the
current flowing through it.
For a real Zener diode, the voltage across it will change slightly for changes of
test current.
The Slope Resistance is the apparent resistance that results in the small change
of Zener voltage due to changes in Zener current. Slope Resistance for a
particular Zener is not a fixed value over different test currents because the
voltage/current graph is not a straight line.
The graph here shows a close-up of the previous example. A straight-line
tangent has been drawn on the curve at the point the Slope Resistance is
determined. The gradient of that line is the inverse of the Slope Resistance.
S
L
O
P
E
=
∆
V
∆
I
∆
I
∆
V
Generally, as the current through a Zener increases, the Slope Resistance
decreases (the V/I curve becomes steeper).
SmA
ZEN50 User Guide September 2015 – Rev 2
Page 9
Your selected nominal
test current
Slope Resistance
continued
The Atlas ZEN determines the Slope Resistance by automatically adjusting the
test current above and below the selected test current and measuring the
resulting Zener voltage that occurs. The instrument chooses 3 currents for
calculating Slope Resistance:
Range Lower Test
Current*
Middle Test
Current
Upper Test
Current*
1 1mA 2mA 3mA
2 2.5mA 5mA 7.5mA
3 5mA 10mA 15mA
4 7.5mA 15mA 22.5mA
The Voltage/Current curve for a Zener diode is not a straight line so it’s not
very accurate to calculate the Slope Resistance using just the lower and upper
current and voltage readings.
The Atlas ZEN uses 3 sets of current and voltage readings to derive a curve
that fits 3 points on the graph. The gradient of the curve is then calculated at
the selected nominal test current using a differentiated version of the curve.
This gives a much more accurate gradient measurement at the actual selected
nominal test current compared to the average (straight line) gradient between
the upper and lower test currents.
The resolution (step size) of displayed Slope Resistance is ultimately limited
by the small changes of Zener voltage that result from the change in Zener
current. The displayed resolutions are as follows:
Range Nominal Test Current Displayed Resolution*
1 2mA 5Ω
2 5mA 2Ω
3 10mA 1Ω
4 15mA 1Ω
* Subject to revision.
ZEN50 User Guide September 2015 – Rev 2
Page 10
Testing LEDs and other diodes
The Atlas ZEN can measure the forward voltage drop of LEDs and other
diodes.
Take care to connect the LED or diode the right way round to ensure
that it is not exposed to large reverse voltages. Do not attempt to test an
LED in reverse with this instrument, even for a split second, you will
break your LED. See the next page for information about the probe
voltages.
Red
Anode(+) Cathode(-)
Black
Red
Anode(+)
Cathode(-)
Black
The Anode(+) of the LED or diode should be connected to the red probe.
The Cathode(-) of the LED or diode should be connected to the black probe.
The unit will happily test almost any LED type, regardless of the LED’s
forward voltage requirements. The current is controlled by the instrument and
the voltage across the LED will automatically settle to the LED’s normal
operating voltage (up to a maximum of 50V for long LED strings).
It is important to appreciate that the test currents applied by the Atlas ZEN are
very short and will result in very low apparent brightness of your LED. This
does no harm but it does mean that your LED will appear much dimmer than
you expect at the selected test current.
ZEN50 User Guide September 2015 – Rev 2
Page 11
Test Voltages
For all the test currents, the voltage developed across the probes can rise to
about 60V*. This is to ensure that Zeners of up to 50V can be adequately
tested. The test current is controlled to ensure that the same current flows
regardless of the device under test (for the range of terminal voltages of 0V to
50V).
Although the current is electronically limited (to less than a peak of 35mA), it
is important to be aware that 60V (across the open circuit probes) could
potentially damage a sensitive component. For example, many LEDs can be
damaged if the reverse voltage across them rises above 5V. There will be no
problem when testing an LED in a forward direction (as the current is
electronically limited and the voltage across the LED will automatically settle
to the LED’s operating voltage). But if an LED is accidentally connected in
reverse across the probes then the voltage could easily reach 60V and the LED
would be damaged.
In all cases, the voltage appearing across the probes will never be higher than
60V. Often the actual voltage will be limited by the device under test at the
selected test current.
The test currents are applied in short pulses to minimise power
consumption and to minimise power dissipation in your component
(Zener voltage can change slightly with temperature due to self-
heating). For this reason, it is not possible to accurately test Zeners
that have any load or significant capacitance across them**. See
next page for more details on loading.
*
60V pulsed DC satisfies lower limit of 75V(DC) for Low Voltage Directive 2006/95/EC.
**
Worst case is Vz=50V, Rslope=8000Ω. 1.2nF in parallel gives 1% Vz error and 3% Rslope error.
' 2mA Range . : : : \ : - . 5mA Range Orhii Rahée
ZEN50 User Guide September 2015 – Rev 2
Page 12
Loading Limitations
To keep power dissipation very low in your component, the Atlas ZEN uses
short pulses to measure the characteristics. This means that accuracy can be
influenced by capacitive (and resistive loading).
Capacitive Loading - Depending on the Zener’s slope resistance, the
following capacitive loads will influence Vz measurements by 1% or more:
1
10
100
1000
10 100
1000
8000
Slope Resistance (Ohms)
Max. Load Capacitance (nF)
Resistive Loading - Depending on the selected test current range, the
following resistive loads will influence Vz measurements by 1% or more:
1
10
100
1000
0 5 10 15 20 25 30 35
2mA Range
5mA Range
10mA Range
15mA Range
40 45 50
Zener Voltage Vz (V)
Min. Load Resistance (kΩ)
=+==+= . | .:u_._| Eieat.1'..E-. -':.4 E] :45 :43:
ZEN50 User Guide September 2015 – Rev 2
Page 13
Care of your Atlas ZEN
The Atlas ZEN should provide many years of service if used in accordance
with this user guide. Care should be taken not to expose your unit to excessive
heat, shock or moisture. Additionally, the battery should be replaced at least
every 12 months to reduce the risk of leak damage.
If a low battery message appears (during start-up) or a battery symbol appears
while you’re using your instrument, then immediate replacement of the battery
is recommended as measured parameters may be affected. The unit may
however continue to operate.
The battery can be replaced by placing the instrument “face down” and then
removing the three screws from the rear of the unit. Take care not to touch the
electronics.
Avoid touching
this area
We recommend that the battery is replaced with a high quality battery
equivalent to an Alkaline AAA, LR03 or MN2400 (1.5V). Replacement
Alkaline AAA batteries are available from many retail outlets.
DO NOT OVER-TIGHTEN THE SCREWS
ZEN50 User Guide September 2015 – Rev 2
Page 14
Self Test Procedure
Each time the Atlas ZEN is powered up, a self test procedure is performed. In
addition to a battery voltage test, the unit measures the performance of many
internal functions such as the voltage and current sources, amplifiers and the
analogue to digital converters. If any of these function measurements fall
outside tight performance limits, a message will be displayed and the
instrument will switch off automatically.
If the problem was caused by a temporary condition on the test clips, such as
applying power to the test clips, then
simply re-starting the Atlas ZEN may
clear the problem.
If a persistent problem does arise, it is likely that damage has been caused by
an external event such as excessive power being applied to the test clips or a
large static discharge taking place. If the problem persists, please contact us for
further advice, quoting the displayed fault code.
If there is a low battery condition, the automatic self test procedure
may not be performed. For this reason, it is highly recommended that
the battery is replaced as soon as possible following a “Low Battery”
warning.
LCD Contrast Adjustment
The contrast of the LCD can be adjusted to your personal preference or
viewing angle. There are 6 steps of contrast adjustment available.
To step through each setting, simply hold down the on-test button and briefly
press the scroll button repeatedly until your desired contrast is obtained. Then
release the on-test button.
Self test failed
CODE: 5
25° Parameter
ZEN50 User Guide September 2015 – Rev 2
Page 15
Appendix A - Technical Specifications
All values are at 25°C unless otherwise specified.
Parameter Min. Typ. Max. Notes
Zener voltage range (Vz) 0.0V 50.0V
Nominal test currents (Iz) 2mA, 5mA, 10mA, 15mA
Set test current accuracy ±1% ±0.2mA
Zener voltage accuracy ±1% ±40mV
Zener voltage resolution 20mV 40mV
O/C test voltage (pulsed) 60V 1
S/C test current (pulsed) 35mA
Test current duty cycle 0.1% 1% 5% 2
External abuse voltage ±50V
Slope resistance range 0Ω
0Ω
0Ω
0Ω
8000Ω
3200Ω
1600Ω
1000Ω
Iz=2mA
Iz=5mA
Iz=10mA
Iz=15mA
Displayed Slope
resistance resolution
5Ω
2Ω
1Ω
1Ω
Iz=2mA
Iz=5mA
Iz=10mA
Iz=15mA
Slope resistance accuracy
±1% ±10Ω
±1% ±4Ω
±1% ±2Ω
±1% ±2Ω
Iz=2mA
Iz=5mA
Iz=10mA
Iz=15mA
Slope res. current span (Iz-50%) to (Iz+50%) 3
Slope resistance
measurement method
Differentiation of curve that fits:
(Iz-50%,Vz1), (Iz,Vz2) and (Iz+50%,Vz3) 3
Measurement rate 3Hz
Auto-off period 60 seconds
Battery type AAA Alkaline
Battery voltage range 0.9V 1.6V
Low battery warning 1.0V ± 0.05V
Dimensions (excl. leads) 103x70x20mm
Operating temperature 10°C 40°C
1. 60V pulsed DC satisfies lower limit of 75V(DC) for Low Voltage Directive 2006/95/EC.
2. Duty cycle of test current designed to keep power dissipation of Zener under test to very low levels.
3. Subject to revision.
IE I
ZEN50 User Guide September 2015 – Rev 2
Page 16
Appendix B – Warranty Information
Peak Warranty
The warranty is valid for 24 months from date of purchase. This warranty
covers the cost of repair or replacement due to defects in materials and/or
manufacturing faults. The warranty does not cover malfunction or defects
caused by:
a) Operation outside the scope of the user guide.
b) Unauthorised access or modification of the unit (except for battery
replacement).
c) Accidental physical damage or abuse.
d) Normal wear and tear.
All claims must be accompanied by a proof of purchase.
Appendix C – Disposal Information
WEEE (Waste of Electrical and Electronic Equipment),
Recycling of Electrical and Electronic Products
In 2006 the European Union introduced regulations (WEEE) for the collection
and recycling of all waste electrical and electronic equipment. It is no longer
permissible to simply throw away electrical and electronic equipment. Instead,
these products must enter the recycling process. Each individual EU member
state has implemented the WEEE regulations into national law in slightly
different ways. Please follow your national law when you want to dispose of
any electrical or electronic products.
More details can be obtained from your national WEEE recycling agency.
At Peak Electronic Design Ltd we are committed to continual product development and improvement.
The specifications of our products are therefore subject to change without notice.
© 2015 Peak Electronic Design Limited - E&OE
Designed and manufactured in the UK
www.peakelec.co.uk Tel. +44 (0) 1298 70012