An Automated DC Power Measurement System for Power Modules

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An Automated DC Parameter
Measurement System for Power
Modules and Smart Power ICs
Using the HP 4142B Modular DC
Source/Monitor
Application Note 12 16-2
1. Introduction
The HP 4 142B Modular DC Source/
Monitor with one HP 41422A
High Current Unit (HCU) and one
HP 4 1423A High Voltage Unit
(HVU) can source/measure up to
lOA/lOOOV. This can be easily
extended to 2OAl2OOOVby using
two HCUs and two HVUs.
Another unique feature of the
HP 4142B is its ability to control
external relays. The External Relay
Control function was designed so you
could programmatically change the
connections between the measurement units and the test device’s
terminals. In addition, the 16-bit
control signal can be used as control
signal sources for smart power ICs.
Figure
1. Example
of the External
Relay
Control
These all combine to create an
economical and highly automated
20A/20OOV dc parametric system for
power devices, power modules, and
smart power ICs.
2. External Relay Control
Function
In addition to controlling the Module
Selector (HP 1608719 or HP 16088B
Option 300) the HP 4142B Control
Unit can output a 16-bit digital TTL
level signal. This added capability is
extremely useful for controlling
external relays under program
control. Figure 1 is an illustration of
this capability.
The relay’s coil should be connected
between the appropriate Control Unit
pin and an external power supply or
VS of HP 41424A Voltage Source/
Voltage Monitor Unit (VS/VMU). A
coil suppression diode should be
connected across the relay coil. The
relay’s contacts should be connected
between the device and measurement
unit which is best suited for your
application. With the HP 4142B you
can choose from the HPSMU,
MPSMU, HCU, VS/VMU and
GNDU. Please refer to the HP 4142B
data sheet for module specifications.
The 16-bit TTL level digital signal
can also be used as input signals for
smart power ICs. Even simple digital
patterns can be generated.
As an added degree of flexibility, you
can use the 16-bit digital signal
directly from the Control Unit or
from the HP 16087A Module
Selector. A special cable interconnects the Control Unit and Module
Selector. See figure 2 for more
information.
The Control Unit connector’s pin
assignment is depicted in figure 3.
Pins 9 through 13 and 22 through 25
are dedicated to the Module Selector.
3. Application
Examples
Figure
The following sections describe
how to programmatically evaluate
bipolar power transistors and power
modules up to 2OA/2OOOVusing the
HP 4142B, External Relay Control
function, and HP 1608714 Module
Selector. A useful example of how
to control smart power ICs is also
described.
In this example, the first HP 4142B
mainframe contains two HCUs and
the second two HVUs. This combination will allow you to perform
automatic measurement up to
2oA/2ooov.
Selector
Module
Control
Board
(HP parts
NO:
16087-66501)
Selector
Pins
I
I
I
4. Automatic Power Device
Measurements to
20A/2000V
The HP 4142B can support a maximum of two HPSMUs (HP 41420A
Source Monitor Unit), two HCUs
(HP 41422A High Current Unit), or
two HVUs (HP 41423A High
Voltage Unit) at the same time. In
addition, multiple HP 4142B mainframes can be used together.
2. Module
External
Control
;
:
Relay
Pins
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;
;
.
.
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.111114-.-.-1-.1.1‘-.-.-.-.-.-.-.-.-.-”-.-.-~-.-.-.-~
D-SUB
Figure
3. Control
Unit
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Connector
23
pins
( ihch-type
Pin Assignment
Screw,
-I
Female )
4-1. Measurement
Configuration
Figures 4 and 5 illustrate the
HP 4142B and module configuration
for measurements to 2OA/2OOOV.The
components outside the dotted line
are standard HP 4 142B measurement
modules. A VWVMU is used to drive
the external relays and it is necessary
to short the common terminals of the
GNDUs.
Table 1 lists the relays and their
specifications used in this example.
Figure 6 shows the Module Selector
wiring. The digital control signals for
the external relays are provided from
the Module Selector. Refer to
Appendix A for more details on
wiring the Module Selector to the test
device.
HP 1,428
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Figure
4.20A/2OOOV
Example
Figure
5.2OA/2OOOV
Equivalent
3
HCU
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,.,
HPSMU
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Table 1. Relay Specifications
HPSMU
“’
ObOU
: GtosAl
Unit
“““2
Unit
: HP 41423A
High Voltage
Unit
: HP 41420A
SouvCa Monitor
: HP 41424A Voltage
AFU
: HP 41425A Analog
Configuration
Measurement
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: HP 41422A High &rrent
VSNMU
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Circuit
Unit
Source/Voltage
Feedback
Unit
‘Monitor Unit
4-2. Example Measurements
and Results
The circuit shown in figure 5 can be
used to measure a device’s collector
to emitter breakdown voltage and
Vc-Ic characteristics. Table 2
illustrates the external relay and
Module Selector settings required for
each measurement. Refer to Appendix B for the measurement program.
4-2-l.
Collector-Emitter
Breakdown Voltage (Bvceo)
Figure
6. Module
Selector
Wiring
The Bvceo measurement circuit is
shown in figure 7. HVU2 is connected to the emitter and set to
-lOOOV. HVUl is connected to the
collector and is swept over the
equivalent measurement range.
.:
Since the HVU is unipolar, HVUl
needs to be set negative and switched
positive while passing through OV.
By adding 1OOOVto the measurement
result of HVU 1, you can obtain the
Vc-Ic characteristics and determine
the device’s Bvceo (see figure 8).
‘.’
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Figure
,..
7. Bvceo
,‘,
Measurement
“,
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Circuit
Table 2. Relay and Module Selector Settings
r-emitter
breakdown
volta
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Note 1) Relays 2-5 are dual relays, Force and Sense lines.
Note 2) The direction of the reed relay must be considered.
Note 3) A series resistor must be used to prevent exceeding the 18.OV relay coil rating.
4
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The HW has a 1OmA maximum
current compliance.
,,
4-2-2. Vc-Ic Characteristics
.‘,.‘\,.“’
The Vc-Ic measurement circuit is
shown in figure 9. The HCUs are
connected in parallel between the
collector and emitter. A 2 channel
pulsed sweep mode is used to
synchronize the HCUs and minimize
thermal generation affects. Each
HCU is sweep from OA to lOA, the
combined current is therefore OA
to 20A.
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The Vc-Ic measurement result is
shown in figure 10.
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Figure
8. Bvceo
Measurement
Result
Figure
9. Vc-Ic
Measurement
Circuit
Figure
10. Vc-Ic
Measurement
Circuit
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5. Automatic Measurements
on Power Modules
The measurement circuit shown in
figure 11 can be used to automate
your power MOSFET modules
measurements. Using the External
Relay Control function and Module
Selector can greatly simplify your
measurements.
6. Automatic Measurements
on Smart Power ICs
The HP 4142B Control Unit makes
controlling smart power ICs a simple
task by programmatically varying the
input signals in order to get the device
into its different states without using
external digital sources.
Figure 12 is an example of how
to connect a motor driver IC and
BP 4142B Control Unit. In this
application, the TTL outputs are used
as inputs to the IC’s control logic. The
IC’s outputs can then be monitored by
HP 4142B’s measurement units.
Figure
11. Power
Module
Measurement
Circuit
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Figure
6
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the Control
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Appendix A
In order to obtain maximum measurement performance and safety, care
must be taken in wiring the Module
Selector to the Test Device:
1. To decrease the chance of
oscillation, minimize the cable
length between Module Selector
and test device. The HCU also
used a special twisted pair wiring
scheme to minimize inductance.
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16 Wire 8150-
2. Be sure to use the INTLK
terminal and HVU ON/OFF
STATUS terminal as shown in
figure 13 to reduce the risk of
electric shock.
Figure
7
A. Connecting
the Module
Selector
and Test Device