DG459 VISHAY [Vishay Siliconix], DG459 Datasheet - Page 8

• Manufacturer Part Number: DG459
• Description: Fault-Protected Single 8-Ch/Differential 4-Ch Analog Multiplexers
• Manufacturer: VISHAY [Vishay Siliconix]

DG458/459
Vishay Siliconix
The Vishay Siliconix DG458 and DG459 multiplexers are fully
fault- and overvoltage-protected for continuous input voltages
up to
supply pins (V+, V–). These multiplexers are built on a
high-voltage junction-isolated silicon-gate CMOS process.
Two n-channel and one p-channel MOSFETs are connected
in series to form each channel (Figure 1).
Within the normal analog signal range ( 10 V), the r
variation as a function of analog signal voltage is comparable
to that of the classic parallel N-MOS and P-MOS switches.
When the analog signal approaches or exceeds either supply
rail, even for an on-channel, one of the three series MOSFETs
gets
overvoltages even if the multiplexer power supply voltages are
lost. This protection is good up to the breakdown voltage of the
respective series MOSFETs. Under fault conditions only sub
microamp leakage currents can flow in or out of the multiplexer.
This not only provides protection for the multiplexer and
succeeding circuitry, but it allows normal, undisturbed
operation of all other channels. Additionally, in case of power
loss to the multiplexer, the loading caused on the transducers
and signal sources is insignificant, therefore redundant
multiplexers can be used on critical applications such as
telemetry and avionics.
www.vishay.com FaxBack 408-970-5600
5-8
cut-off,
35 V whether or not voltage is applied to the power
50
providing
EN
A
A
A
0
1
2
GND
DG458
V+
inherent
+15 V
–15 V
V–
S
2
– S
S
D
8
1 k
1
protection
+5 V
FIGURE 5. Enable Delay
35 pF
against
DS(on)
V
O
Overvoltage
Overvoltage
n-Channel
MOSFET
is On
n-Channel
MOSFET
is On
–35 V
–35 V
Switch
Output
Enable
Input
(b) Overvoltage with Multiplexer Power On
V
(a) Overvoltage with Multiplexer Power Off
O
FIGURE 6. Overvoltage Protection
p-Channel
MOSFET
is Off
p-Channel
MOSFET
is Off
S
–15 V
–15 V
3 V
0 V
0 V
t
V
ON(EN)
G
S
Q
Q
1
D
1
–35 V
S
+15 V
+15 V
G
50%
Q
Q
2
D
2
90%
S
S-52433—Rev. F, 06-Sep-99
–15 V
Document Number: 70064
G
n-Channel
MOSFET
is Off
Q
Q
3
D
3
+35 V
Overvoltage
n-Channel
MOSFET
is Off
+35 V
Overvoltage
t
OFF(EN