MAX16048 Maxim Integrated Products, MAX16048 Datasheet - Page 57

• Manufacturer Part Number: MAX16048
• Description: (MAX16046 / MAX16048) 12-Channel/8-Channel EEPROM-Programmable System Managers
• Manufacturer: Maxim Integrated Products

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Some applications require filtering of the DAC outputs.
This is especially necessary in applications that require
a large distance between the power supplies to be
margined and the MAX16046/MAX16048, or those that
require immunity to noise. A simple RC filter may be
inserted (see Figure 16).
The calculations change slightly for this configuration.
For DC margining calculations, R
culate the lowpass cutoff frequency, use the following
formula:
Place resistor R
possible to the feedback node.
To connect the MAX16046/MAX16048 to a power sup-
ply using the trim input method, see Figure 17.
Calculate the output voltage, V
where V
ply; R
power supply; R
ing the trim input to the DACOUT_ output; and
V
Figure 15. Connections for Margining Using Feedback Method
DACOUT_
System Managers with Nonvolatile Fault Registers
V
OUT
1
, R
REF
DC-DC OR LDO
=
2
is the output voltage of the DACOUT_ output.
12-Channel/8-Channel EEPROM-Programmable
⎛
⎜
⎝
, R
1
is the reference voltage of the power sup-
V
+
REF
3
R
R
, and R
5
3A
2
1
is an optional series resistor connect-
______________________________________________________________________________________
⎞
⎟
⎠
and the capacitor, C, as close as
⎛
⎜
⎝
OUT
R V
f
FB
3 DACOUT_
=
4
2 R C
π
are resistors internal to the
R
R
1
Filtering the DAC Outputs
1
2
3B
R
OUT
3
R
3
+
3
R
, as follows:
+
= R
4
Trim Input Method
(R
+
4
3A
R
+
5
MAX16046
MAX16048
+ R
R )V
5 REF
V
DACOUT_
3B
. To cal-
⎞
⎟
⎠
Calculate the ratio of R
mula:
Resistors R
may be derived from the formulas given in the DC-DC
converter data sheet where trim input functionality is
discussed. DC-DC module data sheets usually include
trim-up and trim-down formulas in the following form:
where Δ is the fraction of the total correction.
Another form of trim-up and trim-down formulas may
appear as follows:
Figure 16. DACOUT Filter
TRIM DOWN :R
TRIM UP :R
TRIM DOWN :R
TRIM UP :R
DC-DC OR LDO
ADJ_UP
ADJ_UP
V
REF
3
ADJ_DOWN
ADJ_DOWN
and R
⎛
⎜
⎝
( )
OUT
( )
k
k
1
FB
Ω
Ω
+
−
4
=
⎛
⎜
⎜ ⎜
⎝
R
R
=
R k
⎛
⎜
⎜
⎝
2
( )
1
and the reference voltage V
⎛
⎜
⎝
3
k
V
R
R
1
( )
( )
k
V
Ω
1
2
⎞
⎟ =
⎠
OUT_NOM
R
Ω
OUT_NOM
Ω
and R
3A
=
V
×
=
REF
⎛
⎜
⎝
V
100
R k
⎛
⎜
⎝
OUT_NOM
3
1
( )
V
−
2
Δ
(
+
REF
R k
C
Ω
V
Δ
Δ
(
using the following for-
3
REF
R
%
R k
⎞
⎟
⎠
−
3B
( )
Δ
×
R k
4
1
%
⎞
⎟
⎠
100
Ω
( )
3
Δ
⎛
⎜
⎝
( )
Ω
%
1
×
Ω
−
Δ
−
(
+
100
Δ
(
R k
R k
−
⎞
⎟
⎠
4
3
R k
R k
( )
( )
+
MAX16046
MAX16048
4
3
Ω
Δ
Ω Δ
( )
( )
%
Ω
Ω
)
+
V
)
)
DACOUT_
R k
%
⎞
⎟
⎟
⎠
−
3
⎞
⎟
⎟
⎠
R k
( )
4
Ω
( )
REF
)
Ω
⎞
⎟
⎠
57