MC145705 Motorola, MC145705 Datasheet - Page 6

• Manufacturer Part Number: MC145705
• Description: (MC145706 / MC145707) 5 Volt Only Driver/Receiver with an Integrated Standby Mode
• Manufacturer: Motorola

V CC
Digital Power Supply
ply. This pin should have a 0.33 F capacitor to ground.
GND
Ground
ground pin of the EIA–232–D connector (Pin 7) as well as to
the logic power supply ground.
V DD
Positive Power Supply
and the positive power supply input of the driver/receiver
sections of the device. This pin requires an external storage
capacitor to filter the 50% duty cycle voltage generated by
the charge pump.
V SS
Negative Power Supply
inverter and the negative power supply input of the driver/
receiver sections of the device. This pin requires an external
storage capacitor to filter the 50% duty cycle voltage gener-
ated by the charge pump.
TxEN
Output Enable
logic low level, the condition of the driver outputs (Tx1 – Tx3)
are in keep OFF (mark
STB
Standby
nected to the logic high level. During the standby mode,
driver and receiver output pins become high impedance
MC145705 MC145706 MC145707
6
DRIVER
RECEIVER
DO1 – DO3
This digital supply pin is connected to the logic power sup-
Ground return pin is typically connected to the signal
This is the positive output of the on–chip voltage doubler
This is the negative output of the on–chip voltage doubler/
This is the driver output enable pin. When this pin is in
The device enters the standby mode while this pin is con-
(OUTPUT)
(OUTPUT
Rx1 – Rx3
Tx1 – Tx3
DI1 – DI3
(INPUT)
(INPUT)
)
t PHL
90%
PIN DESCRIPTIONS
50%
50%
)
90%
state.
10%
10%
t PHL
t f
t f
t PLH
SWITCHING CHARACTERISTICS
t PLH
t r
t r
+ 3 V
0 V
V OH
V OL
+ 3 V
0 V
V OH
V OL
DRIVER
RECEIVER
STB (INPUT)
STB (INPUT)
DO1 – DO3
state. In this condition, supply current I CC is below 10 A
(Typ) and can be operated with low current consumption.
C2+, C2–, C1+, C1–
Voltage Doubler and Inverter
and inverter, which generate the V DD and V SS voltages.
Rx1, Rx2 (Rx3)
Receive Data Input
between + 3 and + 25 V is decoded as a space, and causes
the corresponding DO pin to swing to ground (0 V). A voltage
between – 3 and – 25 V is decoded as a mark, and causes
the DO pin to swing up to V CC .
DO1, DO2 (DO3)
Data Output
from V CC to GND. Each output pin is capable of driving one
LSTTL input load.
standby mode.
DI1, DI2 (DI3)
Data Input
drivers. Input voltage levels on these pins must be between
V CC and GND.
Tx1, Tx2 (Tx3)
Transmit Data Output
which swing toward V DD and V SS . A logic 1 at a DI input
causes the corresponding Tx output to swing toward V SS .
The actual levels and slew rate achieved will depend on the
output loading (RL/CL).
(OUTPUT)
(OUTPUT)
Tx1 – Rx3
These are the connections to the internal voltage doubler
These are the EIA–232–E receive signal inputs. A voltage
These are the receiver digital output pins, which swing
Output level of these pins is high impedance while in
These are the high impedance digital input pins to the
The level of these input pins are TTL/CMOS compatible.
These are the EIA–232–E transmit signal output pins,
The minimum output impedance is 300
t DAZ
t RAZ
– 5 V
+ 5 V
90%
10%
+ 1.5 V
+ 1.5 V
t DZA
t RZA
HIGH Z
HIGH Z
when turned off.
+ 1.5 V
+ 1.5 V
MOTOROLA
+ 5 V
– 5 V
90%
10%
+ 5 V
0 V
V OH
V OL
+ 5 V
0 V
V OH
V OL