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NO RECOMMENDED REPLACEMENT
contact our Technical Support Center at
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DATASHEET
FN3034
Rev.4.00
April 2003
HS-245RH, HS-246RH, HS-248RH
Radiation Hardened Triple Line Transmitter and Receivers
The HS-245RH is a radiation hardened triple line transmitter,
the HS-246RH is a radiation hardened triple line receiver, and
the HS-248RH is a radiation hardened triple party-line receiver.
These devices are fabricated using the Intersil dielectric
isolation process. These parts are identical in pinout and
function to the original HD-245/246/248. They are also die size
and bond pad placement compatible with the original parts for
those customers who buy dice for hybrid assembly.
Each transmitter-receiver combination provides a digital
interface between systems linked by 100 twisted pair,
shielded cable. Each device contains three circuits
fabricated within a single monolithic chip. Data rates greater
than 15MHz are possible depending on transmission line
loss characteristics and length.
The transmitter employs constant current switching which
provides high noise immunity along with high speeds, low
power dissipation, low EMI generation and the ability to
drive high capacitance loads. In addition, the transmitters
can be turned “off” allowing several transmitters to time-
share a single line.
Receiver input/output differences are shown in the table:
PART NO.
HS-246RH
HS-248RH
INPUT
100
Hi-Z
OUTPUT
Open Collector
6K Pull-Up Resistors
Features
• Electrically Screened to SMD # 5962-96722 and
5962-96723
• QML Qualified per MIL-PRF-38535 Requirements
• Radiation Hardened DI Processing
- Total Dose . . . . . . . . . . . . . . . . . . . . 200 krad(Si) (Max)
- Latchup Free
- Neutron Fluence . . . . . . . . . . . . . . . . . .5 x 10
12
N/cm
2
• Replaces HD-245/246/248
• Current Mode Operation
• High Speed with 50 Foot Cable . . . . . . . . . . . . . . . 15MHz
High Speed with 1000 Foot Cable . . . . . . . . . . . . . . 2MHz
• High Noise Immunity
• Low EMI Generation
• Low Power Dissipation
• High Common Mode Rejection
• Transmitter and Receiver Party Line Capability
• Tolerates -2.0V to +20.0V Ground Differential (Transmitter
with Respect to Receiver)
• Transmitter Input/Receiver Output TTL/DTL Compatible
The internal 100 cable termination consists of 50 from
each input to ground.
HS-248RH ‘‘party line’’ receivers have a Hi-Z input such that
as many as ten of these receivers can be used on a single
transmission line.
Each transmitter input and receiver output can be connected to
TTL and DTL systems. When used with shielded transmission
line, the transmitter-receiver system has very high immunity to
capacitance and magnetic noise coupling from adjacent
conductors. The system can tolerate ground differentials of
-2.0V to +20.0V (transmitter with respect to receiver).
Specifications for Rad Hard QML devices are controlled
by the Defense Supply Center in Columbus (DSCC). The
SMD numbers listed here must be used when ordering.
Detailed Electrical Specifications for these devices are
contained in SMD 5962-96722 and 5962-96723.
Ordering Information
ORDERING NUMBER
5962R9672201QCC
5962R9672201QXC
5962R9672201VCC
5962R9672201VXC
HS9-245RH/PROTO
5962R9672301QCC
5962R9672301QXC
5962R9672301VCC
5962R9672301VXC
5962R9672302QCC
5962R9672302QXC
5962R9672302VCC
5962R9672302VXC
INTERNAL
MKT. NUMBER
HS1-245RH-8
HS9-245RH-8
HS1-245RH-Q
HS9-245RH-Q
HS9-245RH/PROTO
HS1-246RH-8
HS9-246RH-8
HS1-246RH-Q
HS9-246RH-Q
HS1-248RH-8
HS9-248RH-8
HS1-248RH-Q
HS9-248RH-Q
TEMP. RANGE
(
o
C)
-55 to 125
-55 to 125
-55 to 125
-55 to 125
-55 to 125
-55 to 125
-55 to 125
-55 to 125
-55 to 125
-55 to 125
-55 to 125
-55 to 125
-55 to 125
FN3034 Rev.4.00
April 2003
Page 1 of 8
HS-245RH, HS-246RH, HS-248RH
Pinouts
HS9-245RH 14 PIN FLATPACK
HS1-245RH 14 CERAMIC DIP
MIL-STD-1835 CDIP2-T14
TOP VIEW
HS9-246RH/248RH 14 PIN FLATPACK
HS1-246RH/248RH 14 PIN CERAMIC DIP
MIL-STD-1835 CDFP3-F14
TOP VIEW
(-) INPUT 1
(+) INPUT 2
(R1) OUTPUT 3
(-) INPUT 4
(+) INPUT 5
(R2) OUTPUT 6
GND 7
R3
R2
R1
14 VCC (R1 AND R2)
13 VCC (R3)
12 VEE (R1 AND R2)
11 VEE (R3)
10 OUTPUT (R3)
9 INPUT (+)
8 INPUT (-)
1
INPUT 1
1
OUTPUT 2
2
OUTPUT 3
2
INPUT 4
1
INPUT 5
1
OUTPUT 6
SUBSTRATE 7
GND
T2
T1
T3
14 VCC
13 INPUT
2
12 OUTPUT
2
11 OUTPUT
1
10 INPUT
1
9
8
INPUT
2
OUTPUT
2
Test Circuits and Applications
NOTES:
Input: TTLH
10ns
TTHL
10ns
pw = 500ns
f = 1MHz
VOUT
IOUT =
50
OPEN
(
3.2V)
1 IN
2 IN
0V
OPEN
(
3.2V)
0V
VCC = +5V
1
D.U.T.
TPHL
1 OUT
TPLH
0.15V
(
3mA)
0V
VOUT
1
50
1% TRANSMITTER
OUT
VOUT
2
50
1%
2
0.15V
(
3mA)
2 OUT
0V
All timing measurements referenced to 50% V points
FIGURE 1. CIRCUIT #1 TRANSMITTER PROPAGATION DELAY
150mV
(+)
50
(-)
50
VCC = +5V
520
D.U.T.
800
30pF
RECEIVER
OUTPUT
(+)IN
(-) IN
0V
150mV
NOTES:
Input: TTLH
10ns
TTHL
10ns
pw = 500ns
f = 1MHz
RECEIVER
OUT
TPLH
TPHL
0V
VEE = - 5V
5V
NOTE: External 50
resistors needed for HS-248RH
0V
All timing measurements referenced to 50% V points
FIGURE 2. CIRCUIT #2 RECEIVER PROPAGATION DELAY
FN3034 Rev.4.00
April 2003
Page 2 of 8
HS-245RH, HS-246RH, HS-248RH
Test Circuits and Applications
IN
(Continued)
+5V
(+)
1/3
HS-245RH
(-)
(NOTE)
(+)
1/3
HS-248RH
(-)
+5V
-5V
“PARTY-LINE”
RECEIVER
OUTPUT
50
50
+5V
1/3 HS-246RH
RECEIVER
OUT
ENABLE
NOTE: HS-245RH should be driven by open-collector
gates. (Totem-pole output may cause slight reduction in
“on” data current). For more detailed information, refer to
Design Information section of this data sheet.
-5V
FIGURE 3. TYPICAL APPLICATION
Design Information
Voltage Mode Transmission
Data rates of up to 10 million bits per second can be obtained
with standard TTL logic; however, the transmission distance
must be very short. For example, a typical 50 foot low
capacitance cable will have a capacitance of approximately
750pF which requires a current of greater than 50mA to drive
5V into this cable at 10MHz; therefore, voltage mode
transmitters are undesirable for long transmission lines at high
data rates due to the large current required to charge the
transmission line capacitance.
An emitter coupled logic gate is frequently used for a current
mode transmitter. However, ECL gates are not compatible with
TTL and DTL logic and they require considerable power. The
Intersil HS-245RH is a TTL/DTL compatible current mode
transmitter designed for high data rates on long transmission
lines. Data rates of 15 megabits per second can be obtained
with 50 feet of transmission line when using the companion
HS-246RH receiver. Data rates of 2 megabits per second are
easily obtained on transmission lines as long as 1,000 feet.
The Intersil transmitter and receivers feature very low power,
typically 25mW for the transmitter and 15mW for the receiver.
Current Mode Transmission
An alternate method of driving high data rates down long
transmission lines is to use a current mode transmitter. Current
mode logic changes the current in a low impedance
transmission line and requires very little change in voltage. For
example, a 2mA change in transmitter current will produce a
100mV change in receiver voltage independent of the series
transmission line resistance. The rise time at the receiver for a
typical 50 foot cable (750pF) is approximately 30ns for a 2mA
pulse.
Intersil Transmitter/Receivers
The Intersil transmitter/receiver family consists of a triple line
transmitter, two triple line receivers with internal terminations
and a triple party-line receiver. The general characteristics of
the transmitter and receivers are outlined in Table A.
FN3034 Rev.4.00
April 2003
Page 3 of 8
HS-245RH, HS-246RH, HS-248RH
TABLE A. GENERAL TRANSMITTER/RECEIVER CHARACTERISTICS
TRIPLE LINE TRANSMITTER
PARAMETER
Operating Temperature Range
“ON” Output Current
Power Supply Current
Standby Current
Propagation Delay
HS-245RH
-55 to 125
1.0 Min
7.0 Max
33 Max
14 Max
UNITS
o
C
COMMENTS
mA
mA
A
ns
Over Full Temperature Range
Per Transmitter Section
Per Transmitter Section
Over Full Temperature Range
TRIPLE LINE RECEIVER
PARAMETER
Operating Temperature Range
Power Supply
ICC (VCC = +5.0V)
Propagation Delay
RECEIVER TYPE
HS-246RH/248RH
HS-246RH/248RH
All Receivers
LIMITS
-55 to 125
2.6
30
INPUT
Input Impedance and
Output Circuit
HS-246RH
HS-248RH
100
Hi-Z
UNITS
o
C
COMMENTS
mA
ns
Per Receiver Section
Over Full Temperature Range
OUTPUT
Open Collector
6K Pull-Up Resistor
Transmitter
The HS-245RH transmitters have two inputs per transmitter,
either of which is low while the other is open during normal
operation and both inputs are open during standby. For
optimum transmitter performance, the “off” input should be
open circuit rather than being pulled towards +5V, because this
will reduce the “on” output data current. On the other hand, the
“on” and “off” output data current will increase if the “off” input
is held below its open circuit voltage. Open collector gates
such as the 7401 and 7403 or 7405 Hex-Inverter are suitable
for driving the HS-245RH transmitter inputs. By using 2-input
gates as shown in Figure 4, an enable line can be provided so
that more than one transmitter may be connected to a line for
time sharing. When the enable line is low the transmitter will be
disabled and will present a high impedance to the transmission
line as well as requiring very little power supply current.
Complementary input signals may be derived from high speed
inverter gates as shown, or by using the complementary
outputs of a flip-flop. When the transmitter is connected near
the midpoint of a long transmission line or to a line with
terminations at both ends, two transmitter sections should be
paralleled with respective inputs and outputs connected
together in order to drive the reduced impedance. This parallel
transmitter technique can also be used to increase the data
rate on long transmission lines.
IN
G1
G2
G3
ENABLE
1/3
HS-245RH
1/3
HS-246RH
OUT
+5
GND
GND +5V -5V
2K-6K FOR TTL DRIVE
REQUIRED FOR HS-246RH
1/3
HS-248RH
OUT
GND +5V -5V
FIGURE 4. TYPICAL DATA TRANSMISSION SYSTEM
FN3034 Rev.4.00
April 2003
Page 4 of 8
HS-245RH, HS-246RH, HS-248RH
Transmitter Operation
The transmitter alternately applies the current to each of the
two conductors in the twisted pair line such that the total
current in the twisted pair is constant and always in the same
direction. This current flows through either of the two 50V
terminating resistors at the receiver and returns to the
transmitter as a steady DC current on the transmission line
shield. The DC power supply return for the transmitter is
through the receiver terminating resistors (the transmitter
ground pin is only a substrate ground). Therefore, it is essential
that the shield be connected to the power supply common at
both the transmitter and receiver, preferably at the integrated
circuit “ground” pin. More than fifteen twisted pair lines can
share the same shield without crosstalk.
The transmission line used with the Intersil HS-245RH series
transmitter and receivers can be any ordinary shielded, twisted
pair line with a characteristic impedance of 100. Twisted pair
lines consisting of number 20 or 22 gauge wire will generally
have this characteristic impedance. Special high quality
transmission lines are not necessary and standard audio,
shielded-twisted pair, cable is generally suitable.
Since the necessary characteristics for various twisted pair
lines are not readily available, it may be necessary to take
some measurements on a length of the proposed line. To do
this, connect an HS-245RH transmitter to one end of the line
(100 feet or more) and an HS-246RH to the other end. The rise
and fall-times can be measured on the line at both ends and
the constant ‘‘K’’, for that line can be computed as shown in
Figure 5 so that the minimum pulse width can be determined
for any length of line.
Data rates of 2MHz have been obtained using 1,000 feet of
standard shielded, twisted pair, audio cable. Data rates of
15MHz are possible on shorter lengths of transmission line (50
feet).
Receivers
The HS-248RH “party-line” receiver presents a high impedance
load to the transmission line allowing as many as ten HS-248RH
receivers to be distributed along a line without excessive
loading. Figure 3 shows a typical system of a transmitter, a
terminating receiver and a party-line receiver. The transmission
line is terminated in its characteristics impedance by an HS-
246RH or by a pair of 50 resistors connecting each line to the
ground return shield.
Electromagnetic Interference
Very little electromagnetic interference is generated by the
Intersil current mode system because the total current through
the twisted pair is constant, while the current through the shield
is also constant and in the opposite direction. This can be
verified by observing, with a current probe, the total current
through the twisted pair, through the shield and through the
complete shielded, twisted pair cable. In each case a constant
current will be observed with only small variations. Small
pulses may be observed if the complementary inputs to the
transmitter do not switch at the same time. The current will
decrease during the time both inputs are high, and will
increase during the time both inputs are low. These switching
pulses may be observed when using the circuit shown in
Figure 4. The amplitude and shape of these pulses will depend
of the propagation delay of G1, and transition times G2 and
G3. These pulses are generally of no concern because of their
small amplitude and width, but they may be reduced by
increasing the similarity of the waveforms and timing
synchronization of the complementary signals applied to the
transmitter.
In addition to generating very little noise, the system is also
highly immune to outside noise since it is difficult to
capacitively couple a differential signal into the low impedance
twisted pair cable and it is even more difficult in induce a
differential current into the line due to the very high impedance
of the constant current transmitter. Therefore, differential mode
interference is generally not a problem with the Intersil current
mode system. Large common mode voltages can also be
tolerated because the output current of the transmitter is
constant as long as the receiver termination ground is less
than 2V positive with respect to the grounded input of the
transmitter, and is less than 25V negative with respect to the
Transmission Lines
The maximum frequency (or minimum pulse width) which can
be carried by a certain length of a given transmission line is
dependent on the loss characteristics of the particular line. At
low frequencies, there will be virtually no loss in pulse
amplitude, but there will be a degradation of rise and fall-time
which is roughly proportional to the square of the line length.
This is shown in Figure 5. If the pulse width is less than the
rise-time at the receiver end, the pulse amplitude will be
diminished, approaching the point where it cannot be detected
by the receiver.
150mV
LINE
VOLTAGE
AT TRANS-
MITTER
TTLH1
150mV
LINE
VOLTAGE
AT
RECEIVER
TTLH2
TTHL2
TTHL1
0V
TTLH2
TTHL1
0V
TTLH2 TTHL2
MINIMUM PULSE WIDTH
WIDE PULSE
TRLH2 = TTLH1 KL
2
TTHL2 = TTHL1 KL
2
Where: L is Line Length K is
determined by line loss
characteristics
FIGURE 5. TRANSMISSION LINE WAVE-SHAPING
FN3034 Rev.4.00
April 2003
Page 5 of 8
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