www.vishay.com
10
Document Number: 70051
S10-1528-Rev. G, 19-Jul-10
Vishay Siliconix
DG417, DG418, DG419
APPLICATIONS
Micropower UPS Transfer Switch
When V
CC
drops to 3.3 V, the DG417 changes states,
closing SW
1
and connecting the backup cell, as shown in
Figure 10. D
1
prevents current from leaking back towards the
rest of the circuit. Current consumption by the CMOS analog
switch is around 100 pA; this ensures that most of the power
available is applied to the memory, where it is really needed.
In the stand-by mode, hundreds of A are sufficient to retain
memory data.
When the 5 V supply comes back up, the resistor divider
senses the presence of at least 3.5 V, and causes a new
change of state in the analog switch, restoring normal
operation.
Programmable Gain Amplifier
The DG419, as shown in figure 11, allows accurate gain
selection in a small package. Switching into virtual ground
reduces distortion caused by R
DS(on)
variation as a function
of analog signal amplitude.
GaAs FET Driver
The DG419, as shown in figure 12 may be used as a GaAs
FET driver. It translates a TTL control signal into - 8 V, 0 V
level outputs to drive the gate.
Vishay Siliconix maintains worldwide manufacturing capability. Products may be manufactured at one of several qualified locations. Reliability data for Silicon
Technology and Package Reliability represent a composite of all qualified locations. For related documents such as package/tape drawings, part marking, and
reliability data, see www.vishay.com/ppg?70051
.
Figure 11. Micropower UPS Circuit
GND
IN
D
V-
3 V Li Cell
Memory DG417
(5 V)
V+
S
+
–
SW
1
V
L
V
SENSE
R
1
453 k
D
1
V
CC
R
2
383 k
Figure 12. Programmable Gain Amplifier
DG419
+
-
IN
R
1
R
2
V
IN
V
OUT
D
S
1
S
2
Figure 13. GaAs FET Driver
DG419
5 V
V
OUT
D
V-GND
S
2
S
1
V
L
V+
+ 5 V
- 8 V
GaAs FET
