MOTOROLA
SEMICONDUCTOR TECHNICAL DATA
Order this document
by MC145406/D
MC145406
Driver/Receiver
EIA 232–E and CCITT V.28 (Formerly RS–232–D)
The MC145406 is a silicon–gate CMOS IC that combines three drivers
and three receivers to fulfill the electrical specifications of standards
E I A 2 3 2 – E a n d C C I T T V. 2 8 . T h e d r i v e r s f e a t u r e t r u e T T L i n p u t
compatibility, slew–rate–limited output, 300–Ω power–off source imped-
ance, and output typically switching to within 25% of the supply rails. The
receivers can handle up to
±
25 V while presenting 3 to 7 kΩ impedance.
Hysteresis in the receivers aids reception of noisy signals. By combining
both drivers and receivers in a single CMOS chip, the MC145406 provides
efficient, low–power solutions for EIA 232–E and V.28 applications.
Drivers
• ±
5 V to
±12
V Supply Range
•
300–Ω Power–Off Source Impedance
•
Output Current Limiting
•
TTL Compatible
•
Maximum Slew Rate = 30 V/µs
Receivers
• ±
25 V Input Voltage Range When VDD = 12 V, VSS = – 12 V
•
3 to 7 kΩ Input Impedance
•
Hysteresis on Input Switchpoint
P SUFFIX
PLASTIC
CASE 648
16
1
16
1
DW SUFFIX
SOG
CASE 751G
SD SUFFIX
SSOP
CASE 940B
BLOCK DIAGRAM
VDD
RECEIVER
VDD
VCC
15 kΩ
+
–
VSS
1.0 V
Tx2
1.8 V
HYSTERESIS
VDD
Tx3
DRIVER
VCC
300
Ω
Tx
LEVEL
SHIFT
+
–
1.4 V
DI
VSS
Rx3
DO
Rx2
VCC
Tx1
VDD
Rx1
PIN ASSIGNMENT
1
2
3
4
5
6
7
R
D
R
D
R
D
16
15
14
13
12
11
10
VCC
DO1
DI1
DO2
DI2
DO3
DI3
GND
*
Rx
5.4 k
8
9
D = DRIVER
R = RECEIVER
VSS
*Protection circuit
©
Motorola, Inc. 1995
MOTOROLA
REV 4
1/95
MC145406
1
MAXIMUM RATINGS
(Voltage polarities referenced to GND)
Rating
DC Supply Voltages (VDD
≥
VCC)
Symbol
VDD
VSS
VCC
VIR
(VSS – 15) to (VDD + 15)
– 0.5 to (VCC + 0.5)
±
100
PD
TA
Tstg
1.0
– 40 to + 85
– 85 to + 150
mA
W
°C
°C
Value
– 0.5 to + 13.5
+ 0.5 to – 13.5
– 0.5 to + 6.0
Unit
V
This device contains protection circuitry to pro-
tect the inputs against damage due to high static
voltages or electric fields; however, it is advised
that normal precautions be taken to avoid applica-
tion of any voltage higher than maximum rated
voltages to this high impedance circuit. For proper
operation, it is recommended that the voltages at
the DI and DO pins be constrained to the range
GND
≤V
DI
≤
VCC and GND≤ VDO
≤
VCC. Also, the
voltage at the Rx pin should be constrained to
(VSS – 15 V)
≤
VRx1–3
≤
(VDD + 15 V), and Tx
should be constrained to VSS
≤
VTx1–3
≤
VDD.
Unused inputs must always be tied to an ap-
propriate logic voltage level (e.g., GND or VCC for
DI and Ground for Rx.)
Input Voltage Range
Rx1–3 Inputs
DI1–3 Inputs
DC Current Per Pin
Power Dissipation
Operating Temperature Range
Storage Temperature Rate
V
DC ELECTRICAL CHARACTERISTICS
(All polarities referenced to GND = 0 V, TA = – 40 to + 85°C)
Parameter
DC Supply Voltage
VDD
VSS
VCC (VDD
≥
VCC)
Quiescent Supply Current (Outputs unloaded, inputs low)
VDD = + 12 V
VSS = – 12 V
VCC = + 5 V
Symbol
VDD
VSS
VCC
IDD
ISS
ICC
Min
4.5
– 4.5
4.5
—
—
—
Typ
5 to 12
– 5 to – 12
5.0
140
340
300
Max
13.2
– 13.2
5.5
µA
400
600
450
Unit
V
RECEIVER ELECTRICAL SPECIFICATIONS
(Voltage polarities referenced to GND = 0 V, VDD = + 5 to + 12 V, VSS = – 5 to – 12 V, VDD
≥
VCC, TA = – 40 to + 85°C)
Characteristic
Input Turn–on Threshold
VDO1–DO3 = VOL, VCC = 5.0 V
±
5%
Input Turn–off Threshold
VDO1–DO3 = VOH, VCC = 5.0 V
±
5%
Input Threshold Hysteresis
VCC = 5.0 V
±
5%
Input Resistance
(VSS – 15 V)
≤
VRx1–Rx3
≤
(VDD + 15 V)
High–Level Output Voltage (VRx1–Rx3 = – 3 V to (VSS – 15 V))*
DO1–DO3
IOH = – 20
µA,
VCC = + 5.0 V
IOH = – 1 mA, VCC = + 5.0 V
Low–Level Output Voltage (VRx1–Rx3 = + 3 V to (VDD + 15 V))* DO1–DO3
IOL = + 20
µA,
VCC = + 5.0 V
IOL = + 2 mA, VCC = + 5.0 V
IOL = + 4 mA, VCC = + 5.0 V
VOL
—
—
—
0.01
0.02
0.5
0.1
0.5
0.7
Rx1–Rx3
Rx1–Rx3
Rx1–Rx3
Rx1–Rx3
Symbol
Von
Voff
Von–Voff
Rin
VOH
4.9
3.8
4.9
4.3
—
—
V
Min
1.35
0.75
0.6
3.0
Typ
1.80
1.00
0.8
5.4
Max
2.35
1.25
—
7.0
Unit
V
V
V
kΩ
V
* This is the range of input voltages as specified by EIA 232–E to cause a receiver to be in the high or low logic state.
MC145406
2
MOTOROLA
ELECTRICAL SPECIFICATIONS
(Voltage polarities referenced to GND = 0 V, VCC = + 5 V
±
5%, TA = – 40 to + 85°C)
Characteristic
Digital Input Voltage
Logic 0
Logic 1
Input Current
VDI1–DI3 = VCC
DI1–DI3
VIL
VIH
DI1–DI3
Iin
VOH
3.5
4.3
9.2
VOL
– 4.0
– 4.5
– 10.0
300
ISC
—
—
– 4.3
– 5.2
– 10.3
—
—
—
—
—
Ω
mA
±
22
±
60
±
60
±
100
3.9
4.7
9.5
—
—
—
V
—
2.0
—
—
—
—
0.8
—
±
1.0
µA
V
Symbol
Min
Typ
Max
Unit
V
Output High Voltage (VDI1–3 = Logic 0, RL = 3.0 kΩ)
Tx1–Tx3
VDD = + 5.0 V, VSS = – 5.0 V
VDD = + 6.0 V, VSS = – 6.0
VDD = + 12.0 V, VSS = – 12.0 V
Output Low Voltage* (VDI1–3 = Logic 1, RL = 3.0 kΩ)
Tx1–Tx3
VDD = + 5.0 V, VSS = – 5.0 V
VDD = + 6.0 V, VSS = – 6.0 V
VDD = + 12.0 V, VSS = – 12.0 V
Off Source Resistance (Figure 1)
VDD = VSS = GND = 0 V, VTx1–Tx3 =
±
2.0 V
Tx1–Tx3
Output Short–Circuit Current (VDD = + 12.0 V, VSS = – 12.0 V)
Tx1–Tx3
Tx1–Tx3 shorted to GND**
Tx1–Tx3 shorted to
±
15.0 V***
* The voltage specifications are in terms of absolute values.
** Specification is for one Tx output pin to be shorted at a time. Should all three driver outputs be shorted simultaneously, device power dissipation
limits will be exceeded.
*** This condition could exceed package limitations.
SWITCHING CHARACTERISTICS
(VCC = + 5 V
±
5%, TA = – 40 to + 85°C; See Figures NO TAG and NO TAG)
Drivers
Characteristic
Propagation Delay Time
Low–to–High
High–to–Low
RL = 3 kΩ CL = 50 pF
Output Slew Rate
Tx1–Tx3
Minimum Load
RL = 7 kΩ, CL = 0 pF, VDD = + 6 to + 12 V, VSS = – 6 to – 12 V
Maximum Load
RL = 3 kΩ, CL = 2500 pF
VDD = + 12 V, VSS = – 12 V
VDD = + 5 V, VSS = – 5 V
4
—
—
—
—
—
SR
—
±
9
±
30
Tx1–Tx3
RL = 3 kΩ, CL = 50 pF
tPLH
tPHL
—
300
500
V/µs
—
300
500
Symbol
Min
Typ
Max
Unit
ns
Receivers
(CL = 50 pF)
Characteristic
Propagation Delay Time
Low–to–High
High–to–Low
Output Rise Time
Output Fall Time
DO1–DO3
DO1–DO3
DO1–DO3
tPLH
tPHL
tr
tf
—
—
—
—
150
150
250
40
425
425
400
100
ns
ns
Symbol
Min
Typ
Max
Unit
ns
MOTOROLA
MC145406
3
PIN DESCRIPTIONS
1
VDD
14
DI1
16
VCC
Tx1
3
VDD
Positive Power Supply (Pin 1)
The most positive power supply pin, which is typically + 5
to + 12V.
12 DI2
Tx2 5
Vin =
±
2 V
VSS
Negative Power Supply (Pin 8)
The most negative power supply pin, which is typically – 5
to – 12 V.
VCC
Digital Power Supply (Pin 16)
The digital supply pin, which is connected to the logic
power supply (maximum + 5.5 V). V CC
must
be less than
or equal to V DD .
GND
Ground (Pin 9)
Ground return pin is typically connected to the signal
ground pin of the EIA 232–E connector (Pin 7) as well as to
the logic power supply ground.
10
DI3
Tx3
7
VSS GND
8
9
Vin
Rout =
I
Figure 1. Power–Off Source Resistance (Drivers)
DRIVERS
3V
DI1–DI3
50%
0V
tf
Tx1–Tx3
tPHL
90%
10%
tPLH
tr
VOH
VOL
Rx1, Rx2, Rx3
Receive Data Input (Pins 2, 4, 6)
These are the EIA 232–E receive signal inputs whose
voltages can range from (VDD + 15 V) to (VSS – 15 V). A volt-
age between + 3 and (VDD + 15 V) is decoded as a space
and causes the corresponding DO pin to swing to ground (0
V); a voltage between – 3 and (VDD – 15 V) is decoded as a
mark and causes the DO pin to swing up to VCC. The actual
turn–on input switchpoint is typically biased at 1.8 V above
ground, and includes 800mV of hysteresis for noise rejec-
tion. The nominal input impedance is 5 kΩ. An open or
grounded input pin is interpreted as a mark, forcing the DO
pin to VCC.
DO1, DO2, DO3
Data Output (Pins 11, 13, 15)
These are the receiver digital output pins, which swing
from VCC to GND. A space on the Rx pin causes DO to pro-
duce a logic 0; a mark produces a logic 1. Each output pin is
capable of driving one LSTTL input load.
DI1, DI2, DI3
Data Input (Pins 10, 12,14)
These are the high–impedance digital input pins to the
drivers. TTL compatibility is accomplished by biasing the in-
put switchpoint at 1.4 V above GND. However, 5–V CMOS
compatibility is maintained as well. Input voltage levels on
these pins must be between VCC and GND.
Tx1, Tx2, Tx3
Transmit Data Output(Pins 3, 5, 7)
These are the EIA 232–E transmit signal output pins,
which swing toward VDD and VSS. A logic 1 at a DI input
causes the corresponding Tx output to swing toward VSS. A
logic 0 causes the output to swing toward VDD (the output
voltages will be slightly less than VDD or VSS depending upon
the output load). Output slew rates are limited to a maximum
of 30 V per
µs.
When the MC145406 is off (VDD = VSS = VCC
= GND), the minimum output impedance is 300
Ω.
RECEIVERS
+3V
Rx1–Rx3
50%
0V
tPHL
90%
DO1–DO3
50%
10%
tf
tr
tPLH
VOH
VOL
Figure 2. Switching Characteristics
DRIVERS
Tx1–Tx3
tSLH
SLEW RATE (SR) =
3V
–3V
3V
–3V
tSHL
– 3 V – (3 V)
3 V – ( – 3 V)
OR
tSLH
tSHL
Figure 3. Slew–Rate Characterization
MC145406
4
MOTOROLA
APPLICATIONS INFORMATION
The MC145406 has been designed to meet the electrical
specifications of standards EIA 232–E and CCITT V.28.
EIA 232–E defines the electrical and physical interface be-
tween Data Communication Equipment (DCE) and Data
Terminal Equipment (DTE). A DCE is connected to a DTE
using a cable that typically carries up to 25 leads. These
leads, referred to as interchange circuits, allow the transfer
of timing, data, control, and test signals. Electrically this
transfer requires level shifting between the TTL/CMOS log-
ic levels of the computer or modem and the high voltage lev-
els of EIA 232–E, which can range from
±
3 to
±
25 V. The
MC145406 provides the necessary level shifting as well as
meeting other aspects of the EIA 232–E specification.
DRIVERS
As defined by the specification, an EIA 232–E driver pres-
ents a voltage of between
±
5 to
±
15 V into a load of be-
tween 3 to 7 kΩ. A logic 1 at the driver input results in a
voltage of between – 5 to – 15 V. A logic 0 results in a voltage
between + 5 to + 15V. When operating VDD and VSS at
±
7 to
±
12 V, the MC145406 meets this requirement. When operat-
ing at
±
5 V, the MC145406 drivers produce less than
±
5 V at the output (when terminated), which does not meet
EIA 232–E specification. However, the output voltages when
using a
±
5 V power supply are high enough (around
±
4 V) to permit proper reception by an EIA 232–E receiver,
and can be used in applications where strict compliance to
EIA 232–E is not required.
Another requirement of the MC145406 drivers is that
they withstand a short to another driver in the EIA 232–E
cable. The worst–case condition that is permitted by
EIA 232–E is a
±
15 V source that is current limited to 500
mA. The MC145406 drivers can withstand this condition
momentarily. In most short circuit conditions the source
driver will have a series 300
Ω
output impedance needed
to satisfy the EIA 232–E driver requirements. This will re-
duce the short circuit current to under 40 mA which is an
acceptable level for the MC145406 to withstand.
Unlike some other drivers, the MC145406 drivers feature
an internally–limited output slew–rate that does not exceed
30 V per
µs.
RECEIVERS
The job of an EIA 232–E receiver is to level–shift voltages
in the range of – 25 to + 25 V down to TTL/CMOS logic lev-
els (0 to + 5 V). A voltage of between – 3 and – 25 V on Rx1
is defined as a mark and produces a logic 1 at DO1. A volt-
age between + 3 and + 25 V is a space and produces a logic
zero. While receiving these signals, the Rx inputs must pres-
ent a resistance between 3 and 7 kΩ. Nominally, the input re-
sistance of the Rx1–Rx3 inputs is 5.4 kΩ.
The input threshold of the Rx1–Rx3 inputs is typically
biased at 1.8 V above ground (GND) with typically 800 mV of
hysteresis included to improve noise immunity. The 1.8 V
bias forces the appropriate DO pin to a logic 1 when its Rx
input is open or grounded as called for in the EIA 232–E
specification. Notice that TTL logic levels can be applied to
the Rx inputs in lieu of normal EIA 232–E signal levels. This
might be helpful in situations where access to the modem or
computer through the EIA 232–E connector is necessary
with TTL devices. However, it is important not to connect the
EIA 232–E outputs (Tx1–Tx3) to TTL inputs since TTL oper-
ates off + 5 V only, and may be damaged by the high output
voltage of the MC145406.
The DO outputs are to be connected to a TTL or CMOS
input (such as an input to a modem chip). These outputs
will swing from VCC to ground, allowing the designer to op-
erate the DO and DI pins from digital power supply. The Tx
and Rx sections are independently powered by VDD and
VSS so that one may run logic at + 5 V and the EIA 232–E
signals at
±
12 V.
POWER SUPPLY CONSIDERATIONS
Figure 4 shows a technique to guard against excessive
device current.
The diode D1 prevents excessive current from flowing
through an internal diode from the V CC pin to the VDD pin
when VDD < VCC by approximately 0.6 V. This high current
condition can exist for a short period of time during power
up/down. Additionally, if the + 12 V supply is switched off
while the + 5 V is on and the off supply is a low impedance
to ground, the diode D1 will prevent current flow through
the internal diode.
The diode D2 is used as a voltage clamp, to prevent VSS
from drifting positive to VCC, in the event that power is re-
moved from VSS (Pin 12). If VSS power is removed, and the
impedance from the V SS pin to ground is greater than
approximately 3 kΩ, this pin will be pulled to VCC by internal
circuitry causing excessive current in the VCC pin.
If by design, neither of the above conditions are allowed
to exist, then the diodes D1 and D2 are not required.
ESD PROTECTION
ESD protection on IC devices that have their pins accessi-
ble to the outside world is essential. High static voltages ap-
plied to the pins when someone touches them either directly
or indirectly can cause damage to gate oxides and transistor
junctions by coupling a portion of the energy from the I/O pin
to the power supply buses of the IC. This coupling will usually
occur through the internal ESD protection diodes. The key to
protecting the IC is to shunt as much of the energy to ground
as possible before it enters the IC. Figure 4 shows a tech-
nique which will clamp the ESD voltage at approximately
±
15 V using the MMVZ15VDLT1. Any residual voltage which
appears on the supply pins is shunted to ground through the
capacitors C1–C3. This scheme has provided protection to
the interface part up to
±
10 kV, using the human body model
test.
MOTOROLA
MC145406
5
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