Datasheet

LT1999-10/LT1999-20/
LT1999-50
20
1999fb
Figure 8. Solenoid Current Monitor for Non-Grounded Solenoids. This Circuit Performs the
Same Function as Figure 7 Except One End of the Solenoid Is Tied to V
S
. The Common Mode
Voltage of Inputs of the LT1999 Switch Between Ground and One Diode Drop Above V
S
Typical applicaTions
LT1999
4k
0.8k
160k
160k
2µA
0.8k
4k
SHDN
V
+
+
–
+
–
8
2
3
7
6
5
R
G
V
+
V
+
5V
V
S
5V
1999 F08a
1
4
0.1µF
2.5V
0.1µF
SOLENOID
R
SENSE
V
OUT
V
REF
V
SHDN
ON
OFF
V
+
V
+
V
+IN
V
–IN
TIME (50ms/DIV)
V
OUT
(0.5V/DIV)
V
+IN
(10V/DIV)
V
OUT
V
+IN
SOLENOID PLUNGER PULLS IN
SOLENOID RELEASES
1999 F08b