ad1315kz Analog Devices, Inc., ad1315kz Datasheet - Page 6

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ad1315kz

Manufacturer Part Number
ad1315kz
Description
High Speed Active Load With Inhibit Mode
Manufacturer
Analog Devices, Inc.
Datasheet
AD1315
FUNCTIONAL DESCRIPTION
The AD1315 is a complete high speed active load designed for
use in general purpose instrumentation and digital functional
test equipment. The function of the active load is to provide
independently variable source and sink currents for the device to
be tested.
The equivalent circuit for the AD1315 is shown in Figure 11.
An active load performs the function of loading the output of
the device under test with a programmed I
currents are independently programmable. V
tation voltage point at which the load switches from source to
sink mode. The active load may also be inhibited, steering cur-
rent to the I
from the test pin.
The AD1315 accepts differential digital signals at its inhibit
inputs ensuring precise timing control and high noise immunity.
The wide inhibit input voltage range allows for ECL power
supplies of –5.2 V and 0 V, –3.2 V and +2 V, and 0 V and +5 V.
Where speed and timing accuracy are less important, TTL or
CMOS logic levels may be used to toggle the Inhibit inputs of
the AD1315. Single ended operation is possible by biasing one
of the inputs to approximately +1.3 V for TTL or V
CMOS. Care should be taken to observe the 4 V maximum
allowable input voltage.
The I
inputs, corresponding to 0 to 50 mA output currents. The V
input, which sets the I
within the input range of –2 V to +7 V.
V
In Figure 12, V
mums are plotted versus DUT voltage. In the I
higher than V
starts to saturate at approximately –1.5 V. In the I
(V
output starts to saturate at approximately +5.5 V. At +7 V, the
source current will be close to zero.
DUT
DUT
OH
VOLTAGE RANGE
lower than V
and I
OLRTN
COM
OL
DUT
programming inputs accept 0 V to +5 V analog
), the load will sink 50 mA, until its output
Figure 11. Block Diagram
and I
COM
range, I
OH
OHRTN
), the load will source 50 mA until its
/I
OL
OH
switch point, may be set anywhere
pins, effectively disconnecting it
and I
OL
typical current maxi-
OH
COM
or I
OH
OL
is the commu-
OL
mode (V
. These
CC
mode
/2 for
DUT
COM
–6–
Ideally, the commutation point set at V
stantaneous current sink/source switching. Because of I/V
characteristics of the internal bridge diodes, this is not the case.
To guarantee full current switching at the DUT, at least a 1 volt
difference between V
steady state conditions. Because of the relatively fast edge rates
exhibited by typical logic device outputs, this should not be a
problem in normal ATE applications.
INHIBIT MODE LEAKAGE
The AD1315’s inhibit-mode leakage current changes with both
temperature and bias levels. There are two major contributing
effects: transistor reverse-bias collector-base leakage and reverse
leakage in the Schottky-diode bridge. Leakage variations with
V
while both effects contribute to leakage current temperature
variations. Inhibit-mode leakage is weakly dependent on V
and decreases slightly as the difference between V
is reduced. Figure 8 shows typical AD1315 inhibit leakage cur-
rent as a function of V
THERMAL CONSIDERATIONS
The AD1315 is provided in a 0.550"
brazed) gull wing, surface mount package with a
(typ). Thermal resistance (case-to-ambient) vs. air flow for the
AD1315 in this package is shown in Figure 13. The data pre-
sented is for a ZIF socketed device. For PCB mounted devices
(w/30 mils clearance) the thermal resistance should be ~3 to 7%
lower with air flows below 320 lfm
ment in thermal resistance vs. air flow starts to flatten out just
above 400 lfm
NOTES
1
2
Ifm is air flow in linear feet/minute.
For convection cooled systems, the minimum recommended airflow is 400 lfm.
Figure 12. Allowable Current Range for I
DUT
Figure 13. Case-to-Ambient Thermal Resistance vs.
Air Flow
arise primarily from transistor collector-base leakage,
(2)
.
COM
DUT
and V
and temperature.
DUT
(1)
must be maintained in
. Notice that the improve-
COM
0.550", 16-lead (bottom
would provide in-
OH
, I
DUT
JC
OL
of 10 C/W
vs. V
and V
REV. A
COM
DUT
COM

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