DS4426T+TR MAXIM [Maxim Integrated Products], DS4426T+TR Datasheet - Page 13

• Manufacturer Part Number: DS4426T+TR
• Description: Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking
• Manufacturer: MAXIM [Maxim Integrated Products]

In this example, the circuit shown in Figure 8 is used to
margin a +2.0V supply by ±20%. The margined power
supply has a DC-DC converter output voltage, V
+2.0V and a DC-DC converter feedback voltage, V
of +0.8V. To determine the relationship of R
start with the equation:
Substituting V
tionship between R
Figure 8. Example Typical Application Circuit
Example Calculations for an Adjustable
FB
4.7kΩ
*V
Three Channels of Power-Supply Tracking
V
OUT
Applications Information
FB
= +0.8V and V
Quad-Channel, I
______________________________________________________________________________________
AND V
0A
=
R
0A
R
and R
FB
0
VALUES ARE DETERMINED BY THE DC-DC CONVERTER AND SHOULD NOT BE CONFUSED WITH V
= 1.5 x R
4.7kΩ
A
R
0
+
B
0B
R
SDA
SCL
GND
0
is determined to be:
B
OUT
×
0B
V
OUT
DS4426
= +2.0V, the rela-
V
FS0
Power Supply
CC
R
FS0
0A
= 80kΩ
OUT0
and R
OUT
, of
FB
0B
,
,
2
CONVERTER
C-Margining IDACs with
DC-DC
I
current for the DS4426). Summing the currents into the
feedback node, we have the following:
where:
and
To create a ±20% margin in the supply voltage, the
value of V
place, R
OUT0
V
CC
is chosen to be 100µA (midrange source/sink
I
OUT
FB
OUT0
0B
OUT
I
I
is calculated to be 2.67kΩ, and R
R0A
R0B
V
OUT
is set to +2.4V. With these values in
= 2.0V*
I
I
R A
OUT0
R
R
0
0A
0B
= 4kΩ
= 2.67kΩ
I
OUT
R B
=
0
= I
AND V
V
OUT
=
R0B
REF
R
R
V
V
FB
FB
0
0
OF THE DS4426.
- I
−
B
A
= 0.8V*
V
R0A
FB
0A
13
is