HD26LS32
Quadruple Differential Line Receivers With 3 State Outputs
ADE-205-577 (Z)
1st. Edition
Dec. 2000
Description
The HD26LS32 features quadruple line receivers designed to meet the specs of EIA standard RS-422A and
RS-423. This device operates from a single 5 V power supply. The enable function is common to all four
receivers and offers a choice of active high or active low input. Fail safe design ensures that if the inputs
are open, the outputs will always be high.
Logic Diagram
1Y
2Y
3Y
4Y
1A
1B
2A
2B
3A
3B
4A
4B
Enable G
Enable G
HD26LS32
2
Pin Arrangement
(Top view)
1
2
3
4
5
6
7
1B
GND
1A
1Y
2Y
8
Enable G
2A
2B
13
14
15
10
11
12
9
16 VCC
4B
4A
4Y
Enable G
3Y
3A
3B
Function Table
Differential Input Enable Output
A – B G GY
VID ≥ VTH HXH
XLH
V
TL < VID < VTH HX?
XL?
V
ID ≤ VTL HXL
XLL
XLHZ
H : High level
L : Low level
X : Immaterial
? : Irrelevant
Z : High impedance
HD26LS32
3
Absolute Maximum Ratings
Item Symbol Ratings Unit
Supply Voltage VCC*17.0 V
In Phase Input Voltage VIC ±25 V
Differential Input Voltage VID*2±25 V
Enable Input Voltage VIN 7V
Output Sink Current Iout 50 mA
Continuous Total Dissipation PT1W
Operating Temperature Range Topr 0 to +70 °C
Storage Temperature Range Tstg –65 to 150 °C
Notes: 1. All voltage values except for differential input voltage are with respect to network ground
terminal.
2. Differential input voltage is measured at the noninverting input with respect to the corresponding
inverting onput.
3. The absolute maximum ratings are values which must not individually be exceeded, and
furthermore, no two of which may be realized at the same time.
Recommended Operating Conditions
Item Symbol Min Typ Max Unit
Supply Voltage VCC 4.75 5.00 5.25 V
In Phase Input Voltage VIC ——±7.0 V
Output Current IOH — — –440 µA
IOL ——8 mA
Operating Temperature Topr 0 — 70 °C
HD26LS32
4
Electrical Characteristics (Ta = 0 to +70°C)
Item Symbol Min Typ*1Max Unit Conditions
Differential Input High
Threshold Voltage VTH — — 0.2 V VIC = –7 to +7 V VOH = 2.7 V, IOH = –440 µA
Differential Input Low VTL — — –0.2 VOL = 0.4 V, IOL = 4 mA
Threshold Voltage — — –0.2 VOL = 0.45 V, IOL = 8 mA
Input Hysteresis*2 VTH – VTL —30—mV
Enable Input Voltage VIH 2.0 — — V
VIL — — 0.8
Enable Input Clamp
Voltage VIK — — 1.5 VCC = 4.75 V, IIN = –18 mA
Output Voltage VOH 2.7 — — VCC = 4.75 V VID = 1 V, IOH = –440 µA
VOL — — 0.4 VIL (G) = 0.8 V VID = –1 V, IOL = 4 mA
— — 0.45 VID = –1 V, IOL = 8 mA
Off State (High IOZ ——20µAV
CC = 5.25 V VO = 2.4 V
Impedance) Output
Current — — –20 VO = 0.4 V
Line Input Current II—
——
—2.3
2.8 mA VI = 15 V, Other Inputs –10 to +15 V
VI = –15 V, Other Inputs –15 to +10 V
Enable Input Current II (EN) — — 100 µAV
I
= 5.5 V
IIH ——20 V
I
= 2.7 V
IIL — — –0.36 mA VI = 0.4 V
Input Resistance ri 6 9.8 — kΩVIC = –15 to +15 V (Other Inputs AC GND)
Short Circuit Output
Current IOS*3–15 — –85 mA VCC = 5.25 V
Supply Current ICC —5270 V
CC = 5.25 V, VI = 0 V (All Outputs Disable)
Notes: 1. All typical values are at VCC = 5 V, Ta = 25°C,VIC = 0.
2. Hysteresis is the differential between the positive going input threshold voltage and the negative
going input threshold voltage.
3. Not more than one output should be shorted at a time.
Switching Characteristics (VCC = 5 V, Ta = 25°C)
TItem Symbol Min typ Max Unit Conditions
Propagation Delay Time tPLH, tPHL —1725nsC
L
= 15 pF
Output Enable Time tZH, tZL —1522
Output Disable Time tHZ —1522 C
L
= 5 pF
tLZ —2030
HD26LS32
5
1. tPLH, tPHL
Test circuit
Pulse
Generator
Input
CL
Output
Ω2 k
VCC
Ω5 k
2 V
*1 *2 *3
Waveforms
Input A 0 V 0 V
0 V 0 V
tPLH
OH
VOL
V
1.3 V
2.5 V
–2.5 V
2.5 V
–2.5 V
tPHL
1.3 V
Input B
Output
HD26LS32
6
2. tHZ, tZH
Test circuit
Input
Pulse
Generator
2.5 V
2 V
CL
Output Ω2 k
VCC
Ω5 k
S1
*1
*2 *3
*4
Waveforms
Enable G 1.3 V 1.3 V
1.3 V 1.3 V
tZH
OH
V
1.3 V
3 V
0 V
3 V
0 V
tHZ
0.5 V
Output
Enable G
S1 : Open
0 V
1.4 V
S1 : Closed
HD26LS32
7
3. tLZ, tZL
Test circuit
Input
Pulse
Generator
–2.5 V
2 V
CL
Output Ω2 k
VCC
Ω5 k
S2
Waveforms
Enable 1.3 V 1.3 V
1.3 V 1.3 V
tZL
OH
VOL
V
1.3 V
3 V
0 V
3 V
0 V
tLZ
0.5 V
Output
Enable G
S2 : Open S2 : Closed
1.4 V
Notes: 1. The pulse generator has the following characteristics :
PRR = 1 MHz, 50 % duty cycle, tr ≤ 15 ns, tf ≤ 6 ns, Zout = 50 Ω.
2. CL includes probe and jig capacitance.
3. All diodes are 1S2074 (H)
4. To test G input,ground G input and apply an inverted input waveform.
HD26LS32
8
HD26LS32 Line Receiver Applications
The HD26LS32 is a line receiver that meets the EIA RS-422A and RS-423A conditions. It has a high in-
phase input voltage range, both positive and negative, enabling highly reliable transmission to be
performed even in noisy environments.
Its main features are listed below.
• Operates on a single 5 V power supply.
• Three-state output
• On-chip fail-safe circuit
• ±7 V in-phase input voltage range
• ±200 mV input sensitivity
• Minimum 6 k input resistance
A block diagram is shown in figure 1. The enable function is common to all four drivers, and either active-
high or active-low input can be selected.
When exchange is carried out using a party line system, it is better to keep the receiver input bias current
constituting the driver load small, as this allows more receivers to be connected.
Consequently, whereas an input resistance of 4 k or above is stipulated in RS-422A and RS-423A, the
HD26LS32 has been designed to allow a greater margin, with a minimum resistance of 6 k .
Figure 2 shows the input current characteristics of the HD26LS32.
The shaded areas in the graph indicate the input current allowable range stipulated in RS-422A and RS-
423A.
HD26LS32 output is LS-TTL compatible and has a three-state function, enabling the output to be placed in
the high-impedance state, and so making the device suitable for bus line type applications.
With an in-phase input voltage range of ±7 V and a ±200 mV input sensitivity, the HD26LS32 can
withstand use in noisy environments.
Also, since signals sent over a long-distance transmission line require a long transition time, it also takes a
long time to cross the receiver’s input threshold level.
Therefore, the input is provided with hysteresis of around 30 mV to prevent receiver output misoperation
due to noise.
An example of input hysteresis is shown in figure 3.
The fail-safe function consists of resistances R connecting input A to VCC and input B to GND, as shown in
figure 4.
HD26LS32
9
This circuit provides for the receiver input section to be pulled up or down by a high resistance that
prevents it from becoming a driver load so that the output goes high in the event of a transmission line
breakage or connector detachment.
When the input pin is placed in the open state by the pull-up/pull-down resistance, the differential input
voltage VID is as follows:
VID: (VIA – VIB) ≥ 0.2 V
and the output is fixed high.
However, if the receiver-side termination resistance remains connected despite a line breakage or connector
detachment, the output will be undetermined (figure 5).
1Y
2Y
3Y
4Y
1A
1B
2A
2B
3A
3B
4A
4B
Enable G
Enable G
Figure 1 HD26LS32 Block Diagram
5
4
3
2
1
0
–1
–2
–3
–4
–5
–25–20–15–10 –5 0 5 10 15 20 25
Input Voltage Vin (V)
Input Current Iin (mA)
Ta = 25°C+3.25 mA
V
CC
= 0 V
V
CC
= 5.25 V
–3.25 mA
–10 V –3 V +3 V +10 V
Figure 2 Input Voltage vs. Input Current Characteristics
HD26LS32
10
5
4
3
2
1
0
–100 –80 –60 –40 –20 0 20 40 60 80 100
Differential Input Voltage VID (mV)
Output Voltage Vout (V)
VCC = 5 V, Ta = 25°C
VIC = –7 V
VIC = 0 V
VIC = +7 V
Input applied to pin A,
with pin B as reference
Figure 3 Differential Input Voltage vs. Output Voltage Characteristics
VCC
Y
R
R
A
B
Figure 4 Fail-Safe Function
This is because, since the termination resistance is normally matched to the transmission line characteristic
impedance, the value falls to several tens of hundreds of ohms, and the differential input pins are shorted by
this termination resistance. That is, the differential input voltage VID comes within the range
VID: –0.2 V < VIA – VIB < 0.2 V
and the output becomes undetermined.
To prevent this, resistance R1 is inserted in series with the transmission line as shown in figure 6,
minimizing the effect of the termination resistance. Resistance R2 is added to increase the current flowing
between the termination resistance and R1, enabling the value of R1 to be kept small.
Inserting resistances R1 and R2 in this way provides for the differential input voltage VID to become 200 mV
or higher, but the following points must be noted.
• Smallest possible R1 value
If this value is large, the receiver input sensitivity will fall.
• Largest possible R2 value
If this value is small, the load on the driver will be large.
Figure 7 shows experimental differential input voltages for variations in R1 and R2.
HD26LS32
11
"H"
RT
RTUndetermined
Figure 5 Examples of Transmission Line Disconnection
Receiver
VCC
R2
R2
R1
R1
RT
Driver
Figure 6 Method of Enhancing Fail-Safe Function
0.6
0.5
0.4
0.3
0.2
0.10 5 10 15
R1 (kΩ)
Differential Input Voltage VID (V)
R
2
= 30 kΩ
50 kΩ
100 kΩ
300 kΩ
R
2
= ∞
VCC = 5 V
Ta = 25°C
VCC
R2
VID
R2
R1
R1
100 Ω
Figure 7 R1, R2 vs. Differential Input Voltage
HD26LS32
12
RS-442A Interface Standard Applications
Figure 9 shows sample operation waveforms at various points with 1200 m and 12 m cable lengths.
1. Unidirectional Transmission (1 : 1 Configuration)
Receiver
Data
output
F
D
E
Driver B
C
AData
input RT
Figure 8 1 : 1 Unidirectional Transmission
: 1200 m
: 100 kHz
Line
Frequency : 5 µs/div
: 2 V/div
H
V
: 50%
: 100 Ω
Duty
RT
: 12 m
: 10 MHz
Line
Frequency : 50 ns/div
: 2 V/div
H
V
: 50%
: 100 Ω
Duty
RT
A
GND
C
GND
B
GND
D
GND
F
GND
E
GND
A
GND
C
GND
B
GND
D
GND
F
GND
E
GND
Figure 9 Sample Transmission Waveforms
HD26LS32
13
2. Unidirectional Transmission (1 : n Configuration)
Driver
Data
input RT
Data
output Data
output
Receiver
RTData
output
Enable
Data
output
Figure 10 1 : n Unidirectional Transmission
With this connection method, n receivers are connected for one driver. In the RS-422A standard, ten
receivers can be connected simultaneously for one driver.
Conversely, it is also possible to connect one receiver for n drivers.
3. Bidirectional Transmission
Driver Receiver
Data I/O
Enable
DriverReceiver
Data I/O
Enable
RTRT
Figure 11 Bidirectional Transmission
When bidirectional data exchange is performed using a combination of the HD26LS31 and HD26LS32,
since either high or low output control is possible, using complementary enable inputs for the driver and
receiver makes it easy to configure the kind of combination illustrated in figure 11 .
Extending this combination makes it possible to exchange n-bit data simultaneously, and handle a party
line system.
HD26LS32
14
Package Dimensions
Hitachi Code
JEDEC
EIAJ
Mass
(reference value)
DP-16
Conforms
Conforms
1.07 g
Unit: mm
6.30
19.20
16 9
81 1.3
20.00 Max
7.40 Max
7.62
0.25
+ 0.13
– 0.05
2.54 ± 0.25 0.48 ± 0.10
0.51 Min
2.54 Min 5.06 Max
0° – 15°
1.11 Max
Hitachi Code
JEDEC
EIAJ
Mass
(reference value)
FP-16DA
—
Conforms
0.24 g
Unit: mm
*Dimension including the plating thickness
Base material dimension
*0.22 ± 0.05
*0.42 ± 0.08
0.12
0.15
M
2.20 Max 5.5
10.06
0.80 Max
16 9
18
10.5 Max
+ 0.20
– 0.30
7.80
0.70 ± 0.20
0° – 8°
0.10 ± 0.10
1.15
1.27
0.40 ± 0.06
0.20 ± 0.04
HD26LS32
15
Cautions
1. Hitachi neither warrants nor grants licenses of any rights of Hitachi’s or any third party’s patent,
copyright, trademark, or other intellectual property rights for information contained in this document.
Hitachi bears no responsibility for problems that may arise with third party’s rights, including
intellectual property rights, in connection with use of the information contained in this document.
2. Products and product specifications may be subject to change without notice. Confirm that you have
received the latest product standards or specifications before final design, purchase or use.
3. Hitachi makes every attempt to ensure that its products are of high quality and reliability. However,
contact Hitachi’s sales office before using the product in an application that demands especially high
quality and reliability or where its failure or malfunction may directly threaten human life or cause risk
of bodily injury, such as aerospace, aeronautics, nuclear power, combustion control, transportation,
traffic, safety equipment or medical equipment for life support.
4. Design your application so that the product is used within the ranges guaranteed by Hitachi particularly
for maximum rating, operating supply voltage range, heat radiation characteristics, installation
conditions and other characteristics. Hitachi bears no responsibility for failure or damage when used
beyond the guaranteed ranges. Even within the guaranteed ranges, consider normally foreseeable
failure rates or failure modes in semiconductor devices and employ systemic measures such as fail-
safes, so that the equipment incorporating Hitachi product does not cause bodily injury, fire or other
consequential damage due to operation of the Hitachi product.
5. This product is not designed to be radiation resistant.
6. No one is permitted to reproduce or duplicate, in any form, the whole or part of this document without
written approval from Hitachi.
7. Contact Hitachi’s sales office for any questions regarding this document or Hitachi semiconductor
products.
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Tel: Tokyo (03) 3270-2111 Fax: (03) 3270-5109
Copyright Hitachi, Ltd., 2000. All rights reserved. Printed in Japan.
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