Linear Technology DC1480A, Demo Manual, Page: 3 / 8

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dc1480af
DEMO MANUAL DC1480A
Rail Tracking
Demonstration circuit 1480A is configured for independent
turn-on of V
OUT1
and V
OUT2
. The ramp rate for V
OUT1
is
determined by the TRK/SS1 cap at C6 and the ramp rate
for V
OUT2
is determined by the TRK/SS2 capacitor at
C14. This board can be modified on the bench to allow
V
OUT1
to track an external signal. It can also be modified
to allow V
OUT2
to track V
OUT1
or to allow V
OUT2
to track
an external signal. Tables 2 and 3 cover the rail tracking
options for each rail.
Table 2. V
OUT1
Tracking Options (3.3V)
TRACK1 DIVIDER TRK/SS1 CAPACITOR
CONFIGURATION R7 R9 C6
Soft-Start without Tracking (Original Board) 0Ω Not Stuffed 0.1µF
External Coincident Tracking 45.3kΩ 10kΩ Not Stuffed
Table 3. V
OUT2
Tracking Options (1.8V)
TRACK2 DIVIDER TRK/SS2 CAPACITOR
CONFIGURATION R15 R14 R17 C14
Soft-Start without Tracking (Original Board) 0Ω Not Stuffed Not Stuffed 0.1µF
Coincident Tracking to V
OUT1
(3.3V) 0Ω 20kΩ 10kΩ Not Stuffed
External Coincident Tracking 20kΩ Not Stuffed 10kΩ Not Stuffed
Figure 1. Proper Measurement Equipment Setup
QUICK START PROCEDURE
+
–
V
+
–
+
–
V
IN
SUPPLY
I
IN
A
+
I
OUT1
A
I
OUT2
V
IN
A
V
OUT1
LOAD
V
OUT2
LOAD
V
OUT2
V
OUT1
+
–
V
+
–
V
+
+
+