MC145407 데이터 시트보기 (PDF) - Motorola => Freescale
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MC145407 Datasheet PDF : 8 Pages
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APPLICATIONS INFORMATION
ESD CONSIDERATIONS
ESD protection on IC devices that have their pins acces-
sible to the outside world is essential. High static voltages
applied to the pins when someone touches them either di-
rectly 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 busses of the IC. This cou-
pling 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. Fig-
ure 7 shows a technique which will clamp the ESD voltage at
approximately + 15 V using the MMBZ15VDLT1. Any resid-
ual voltage which appears on the supply pins is shunted to
ground through the 0.1 µF capacitors.
OPERATION WITH SMALLER VALUE CHARGE PUMP
CAPS
The MC145407 is characterized in the electrical tables
using 10 µF charge pump caps to illustrate its capability in
driving a companion MC145406 or MC145403. If there is no
requirement to support a second interface device and/or the
charge pump is not being used to power any other com-
ponents, the MC145407 is capable of complying with
EIA–232–E and V.28 with smaller value charge pump caps.
Table 1 summarizes driver performance with both 2.2 µF and
1.0 µF charge pump caps.
Table 1. Typical Performance
Parameter
2.2 µF
Tx VOH @ 25°C
7.3
Tx VOH @ 85°C
7.2
Tx VOL @ 25°C
– 6.5
Tx VOL @ 85°C
Tx Slew Rate @ 25°C
– 6.1
8.0 V/µs
Tx Slew Rate @ 85°C
7.0 V/µs
1.0 µF
7.2
7.1
– 6.4
– 6.0
8.0 V/µs
7.0 V/µs
+5V
0.1 µF
DTMF
INPUT
RDSI
20 kΩ
10 kΩ
TIP
*
20 TLA
CDSI RTLA
6
VDD
Xin 9
1
0.1 µF
DSI
17
TxA
15 RxA2
Xout 8
3
CD
11
TxD
RTx
10 µF 600
+
RxD 5
16
MC145442
RxA1 OR
600:600
MC145443 SQT 14
RING
VDD
0.1 µF
VDD BYPASS
0.1 µF
VSS BYPASS
CFB 18 ExI
10
FB
0.1 µF 19 VAG
4 CDT
0.1 µF
CCDT
2
LB
13
MODE
VSS
12
7
CDA
3.579
MHz
10 kΩ
10 kΩ
10 kΩ
CCDA
0.1 µF
0.1 µF 1.0 µF
0.1 µF
1.0 µF
17 +
19
3 C2 – VDD VCC C1 –
1
C2 +
C1 +
15 DI1
16 DO1
Tx1 6
13 DI2
5
Rx1
MC145407
8
Tx2
1.0 µF
8
2 EIA–232–E
DB–25
CONNECTOR
3
7
DI3
Rx2
7
9
Rx3
VSS GND
4
2
1.0 µF
* Line protection circuit
Figure 4. 5 V, 300 Baud Modem with EIA–232–E Interface
MC145407
6
MOTOROLA
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