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Teilenummer | DS275 |
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Beschreibung | Line-Powered RS-232 Transceiver Chip | |
Hersteller | Dallas Semiconducotr | |
Logo | ||
Gesamt 8 Seiten www.dalsemi.com
DS275
Line-Powered RS-232 Transceiver Chip
FEATURES
Low-power serial transmitter/receiver for
battery-backed systems
Transmitter steals power from receive signal
line to save power
Ultra-low static current, even when connected
to RS-232-E port
Variable transmitter level from +5 to +12
volts
Compatible with RS-232-E signals
Available in 8-pin, 150 mil wide SOIC
package (DS275S)
Low-power CMOS
ORDERING INFORMATION
DS275
8-pin DIP
DS275S
8-pin SOIC
DS275E
14-pin TSSOP
PIN ASSIGNMENT
RXOUT
VDRV
TXIN
1
2
3
8 VCC
7 RXIN
6 NC
GND 4
5 TXOUT
DS275 8-Pin DIP (300-mil)
DS275 8-Pin SOIC (150-mil)
RXOUT
NC
VDRV
NC
TXIN
NC
GND
1
2
3
4
5
6
7
14 VCC
13 NC
12 NC
11 RXIN
10 NC
9 NC
8 TXOUT
DS275E 14-Pin TSSOP
PIN DESCRIPTION
RXOUT
VDRV
TXIN
GND
- RS-232 Receiver Output
- Transmit driver +V
- RS-232 Driver Input
- System Ground (0V)
TXOUT
NC
- RS-232 Driver Output
- No Connection
RXIN
VCC
- RS-232 Receive Input
-System Logic Supply (+5V)
DESCRIPTION
The DS275 Line-Powered RS-232 Transceiver Chip is a CMOS device that provides a low-cost, very
low-power interface to RS-232 serial ports. The receiver input translates RS-232 signal levels to common
CMOS/TTL levels. The transmitter employs a unique circuit which steals current from the receive RS-
232 signal when that signal is in a negative state (marking). Since most serial communication ports
remain in a negative state statically, using the receive signal for negative power greatly reduces the
DS275’s static power consumption. This feature is especially important for battery-powered systems such
as laptop computers, remote sensors, and portable medical instruments. During an actual communication
session, the DS275’s transmitter will use system power (5-12 volts) for positive transitions while still
employing the receive signal for negative transitions.
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112299
DS275
DC ELECTRICAL CHARACTERISTICS (0°C to 70°C; VCC = VDRV = 5V ±=10%)
PARAMETER
SYMBOL MIN TYP MAX UNITS NOTES
TXOUT Level High
TXOUT Level Low
TXOUT Short Circuit Current
TXOUT Output Slew Rate
Propagation Delay
RXIN Input Threshold Low
RXIN Input Threshold High
RXIN Threshold Hysteresis
RXOUT Output Current @ 2.4V
RXOUT Output Current @ 0.4V
VOTXH
VOTXL
ISC
tSR
tPD
VTL
VTH
VHYS
IOH
IOL
3.5 4.0
-8.5 -9.0
+60
5
0.8 1.2
1.6 2.0
0.5 0.8
-1.0
5.0
+85
30
1.6
2.4
3.2
V
V
mA
V/µs
µs
V
V
V
mA
mA
6
7
8
9
NOTES:
1. VDRV must be greater than or equal to VCC.
2. VCC = VDRV = 5V ±=10%.
3. See test circuit in Figure 4.
4. See test circuit in Figure 5.
5. See test circuit in Figure 6.
6. TXIN = VIL and TX OUT loaded by 3 kΩ=to ground.
7. TXIN = VIH, RXIN = -10 volts and TXOUT loaded by 3 kΩ=to ground.
8. TXIN to TXOUT - see Figure 7.
9. VHYS = VTH - VTL.
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6 Page | ||
Seiten | Gesamt 8 Seiten | |
PDF Download | [ DS275 Schematic.PDF ] |
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