HFA5251 查看數據表（PDF） - Intersil
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HFA5251 Datasheet PDF : 10 Pages
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HFA5251
The formatter sends a sequence of digital information to the
pin driver which contains logic information over time. The
active load is enabled when the DUT pin acts as an output. It
simulates the load of the DUT pin by sinking or sourcing
programmed current. Finally the sequencer controls the
overall activities of the automatic testing.
Decoupling Circuit for Oscillation-Free
Operation
To insure the oscillation-free operation in ATE or pulse
generator applications, the pin driver needs an appropriate
decoupling circuit on a printed circuit board which consists of
chip capacitors and chip resistors. Figures 5 and 6 refer to a
proven decoupling circuit currently working in the lab and a
1X scale film of its associated PC board (metal level).
The control pins, DATA, DATA, HiZ, and HiZ are fed ECL
signals through 50Ω micro-strip lines terminated with 50Ω for
impedance matching since the input impedance at these
pins is much higher than 50Ω. At the end of the micro-strip
lines there is usually a high-speed pulse generator with an
output impedance of 50Ω. A 50Ω micro-strip line is
connected to each of the pins, DATA and HiZ through a 50Ω
chip resistor to monitor the pulse signals.
CLOCK,
START
TIMING
HiZ
MEMORY
DATA
FORMATTER
DATA
ACTIVE
LOAD
PIN DRIVER
50Ω
DUT
MEMORY
DATA
EDGE/
WINDOW
COMPARATOR
VCH
VCL
SEQUENCER
FAIL
MEMORY
FAIL
TIMING
DUAL LEVEL COMPARATOR
FIGURE 4. TYPICAL ATE SYSTEM
VHIGH
50Ω
470pF
470pF
PIN 1
µ- STRIP
50Ω
µ- STRIP
100Ω
µ- STRIP
50Ω
µ- STRIP
50Ω
VHIGH VCC1
VHIGH VCC1
DATA
VCC2
DATA VCC2
VOUT
VOUT
HiZ VEE2
VEE2
VCC
0.1µF
10µF
470pF
µ- STRIP
470pF
µ- STRIP
50Ω 100Ω
µ- STRIP
HiZ
VEE
VLOW VEE1
VLOW VEE1
0.1µF
50Ω
VLOW
470pF
470pF
GROUND
10µF
FIGURE 5. DECOUPLING CIRCUIT OF 28 PIN SOIC HFA5251
FOR OSCILLATION-FREE OPERATION
FIGURE 6. 1X FILM OF THE EVALUATION BOARD METAL
The two input voltage pins, VHIGH and VLOW, need to be
protected from any capacitively coupled AC noise. Normally
this protection can be achieved by having a low pass filter
consisting of a 50Ω chip resistor and a 470pF chip capacitor.
Without this protection circuit the pin driver may oscillate due
to signals fed back from the output through the PC board
ground.
The power supply pins, VCC1, VCC2, VEE1, and VEE2,
require decoupling chip capacitors of 470pF, 0.1µF, 10µF.
Having decoupling capacitors close to VCC2 and VEE2 is
7
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