EDGE HIGH-PERFORMANCE PRODUCTS
1
www.semtech.com
Edge647
Pin Electronics Driver, Window
Comparator, and Switch Matrix
Description
Features
Functional Block Diagram
Applications
Revision 2 / October 27, 2000
The Edge647 is an integrated trinary driver, window
comparator, and switch matrix pin electronics solution
manufactured in a wide voltage CMOS process. It is
designed for automatic test equipment and
instrumentation where cost, functional density, and power
are all at a premium.
The tristatable driver is capable of generating 3 levels -
one for a logic high, one for a logic low, and one for either
a termination voltage or a special programming voltage.
The on-board window comparator effectively determines
whether the DUT is in a high, low, or intermediate state.
The switches are included to allow such functions as PMU,
pull up, and pull down connections.
The Edge647 is intended to offer an extremely low leakage,
low cost, low power, small footprint, per pin solution for
100 MHz and below pin electronics applications. It is a
higher performance, pin and functionally compatible
version of the Edge646
.
•
Pin Compatible with the Edge646
•
100 MHz Operation
•
12V I/O Range
•
Programmable Output Levels
•
Flex In digital Inputs (Technology Independent)
•
Three Level Driver
•
Extremely Low Leakage Currents (~0 nA)
•
Small Footprint (32 Pin, 7 mm X 7 mm,
TQFP Package
)
•
Low Cost Automatic Test Equipment
COMPA
HIGH LEVEL
LOW LEVEL
COMPB
LOAD
CVA
VINP
CVB
SW0
SW0 EN*
SW1
SW1 EN*
SW2
SW2 EN*
VBB
VH
VL
DOUT
VTT
DATA
DATA*
DVR EN
DVR EN*
VTT EN
VTT EN*
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2000 Semtech Corp.
www.semtech.com
EDGE HIGH-PERFORMANCE PRODUCTS
Edge647
the DUT. In this environment, the driver can withstand a
short to any legal DUT voltage for an indefinite period.
In a low impedance application with no additional output
series resistance, care must be exercised and systems
should be designed to check for this condition and tristate
the driver if a short is detected.
The driver does NOT have on-chip short circuit protection
or limitation circuitry.
VBB
VBB is an analog input which establishes the threshold
for all single ended digital input signals. If SW0 EN*,
SW1 EN*, or SW2 EN* are more positive than VBB, these
inputs are a digital “1". Conversely, if they are more
negative than VBB, they are a “0".
All digital inputs are wide voltage comparator inputs, so
they are technology independent. By establishing the
appropriate VBB level for the switch control inputs, and
the appropriate differential input levels for the driver digital
control inputs, the Edge647 may be driven by TTL, ECL,
CMOS, or any custom level circuitry.
Figure 1. Driver Digital Inputs
Figure 2. Driver Differential Digital Inputs
Circuit Description
Driver Description
The Edge647 driver supports three distinct programmable
driver
levels; high, low, and termination, and high
impedance. There are no restrictions between any of these
three levels in that all three may vary independently over
the entire operating voltage range between VCC and VEE.
The DVR EN*, DATA, and VTT EN pins are digital inputs
that control the driver (see Table 1). With DVR EN* low,
DATA determines whether the driver will force VH or VL at
DOUT. With DVR EN* high, VTT EN* controls whether the
driver goes into high impedance or drives VTT.
Table 1. Driver Truth Table
VH, VL, and VTT
VH, VL, and VTT define the logical “1”, “0”, and
“termination” levels of the driver and can be adjusted
anywhere over the range spanned by VCC to VEE. There
is no restriction between VH, VL, and VTT, in that they can
all vary independently over the entire voltage range
determined by the power supply levels.
The VH, VL, and VTT inputs are unbuffered in that they
also provide the driver output current, so the sources of
these voltages must have ample current drive capability.
While VTT is referred to as the termination voltage, it may
also be used as a very high “programming” level on many
memory devices.
Driver Output Protection
The Edge647 is designed to operate in a functional testing
environment where a controlled impedance (typically 50
Ω
) is maintained between the pin electronics and the DUT.
In general, there will be an external resistor at the driver
output which series terminates the transmission line to
*
N
E
R
V
D
N
E
T
T
V
A
T
A
D
T
U
O
D
1
0
X
Z
i
H
1
1
X
T
T
V
0
X
0
L
V
0
X
1
H
V
SW0 EN*
SW1 EN*
SW2 EN*
VBB
DATA
DATA*
DVR EN*
DVR EN
VTT EN
VTT EN*