DC1297B Linear Technology, DC1297B Datasheet - Page 11

• Manufacturer Part Number: DC1297B
• Description: BOARD EVAL LTM4612
• Manufacturer: Linear Technology
• Series: µModuler

Specifications of DC1297B

• Design Resources: LTM4612 Spice Model LTM4612 Gerber Files DC1297B Design Files DC1297B Schematic
• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Power - Output: -
• Voltage - Output: 3.3V, 5V ,12V
• Current - Output: 5A
• Voltage - Input: 5 ~ 36 V
• Regulator Topology: Buck
• Frequency - Switching: 850kHz
• Board Type: Fully Populated
• Utilized Ic / Part: LTM4612
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

applicaTions inForMaTion
Output Voltage Programming and Margining
The PWM controller has an internal 0.6V reference voltage.
As shown in the Block Diagram, a 100k internal feedback
resistor connects the V
resistor, R
the output voltage.
or equivalently,
Table 1. R
The MPGM pin programs a current that when multiplied
by an internal 10k resistor sets up the 0.6V reference ±
offset for margining. A 1.18V reference divided by the
Table 2. Output Voltage Response vs Component Matrix (Refer to Figure 20)
TYPICAL MEASURED VALUES
VENDORS
Murata
Murata
R
V
FB
OUT
V
R
V
(V)
10
10
10
12
12
15
15
10
OUT
5
5
5
5
5
5
OUT
FB
(kW)
(V)
=
= 0.6V •
FB
2 × 10µF 50V
2 × 10µF 50V
2 × 10µF 50V
2 × 10µF 50V
2 × 10µF 50V
2 × 10µF 50V
2 × 10µF 50V
2 × 10µF 50V
2 × 10µF 50V
2 × 10µF 50V
2 × 10µF 50V
2 × 10µF 50V
2 × 10µF 50V
2 × 10µF 50V
V
0.6V
FB
(CERAMIC)
22.1
3.3
OUT
Standard 1% Resistor Values vs V
100k
, from the V
C
IN
− 1
13.7
5
100k + R
100µF 50V
100µF 50V
100µF 50V
100µF 50V
100µF 50V
100µF 50V
100µF 50V
100µF 50V
100µF 50V
100µF 50V
100µF 50V
100µF 50V
100µF 50V
100µF 50V
R
(BULK)
OUT
PART NUMBER
GRM32ER61C476KEI5L (47µF , 16V)
GRM32ER61C226KE20L (22µF , 16V)
FB
11
6
C
FB
IN
and V
pin to the SGND pin programs
FB
8.06
8
4 × 47µF 16V
2 × 22µF 16V
4 × 47µF 16V
2 × 22µF 16V
4 × 47µF 16V
2 × 22µF 16V
4 × 47µF 16V
2 × 22µF 16V
4 × 47µF 16V
2 × 22µF 16V
4 × 47µF 16V
2 × 22µF 16V
4 × 47µF 16V
2 × 22µF 16V
FB
(CERAMIC)
6.34
pins together. Adding a
C
10
OUT1
5.23
OUT
12
150µF 25V
150µF 25V
150µF 25V
150µF 25V
150µF 25V
150µF 25V
150µF 25V
4.42
(BULK)
C
14
None
None
None
None
None
None
None
OUT2
4.12
15
V
(V)
12
12
24
24
36
36
24
24
36
36
24
36
28
36
IN
R
Calculate V
Where %V
and V
Where R
pin to ground.
The output margining will be ± margining of the value.
This is controlled by the MARG0 and MARG1 pins. See
the truth table below:
PGM
VENDORS
Murata
TDK
R
V
OUT(MARGIN)
PGM
OUT(MARGIN)
DROOP
resistor on the MPGM pin programs the current.
MARG1
(mV)
111
171
108
153
153
184
178
134
HIGH
HIGH
LOW
LOW
86
86
86
86
83
86
PGM
=
OUT
OUT(MARGIN)
V
0.6V
OUT
is the resistor value to place on the MPGM
is the percentage of V
PEAK (mV)
PEAK-TO-
=
•
156
178
166
169
178
172
209
325
197
288
281
375
338
250
is the margin quantity in volts:
V
%V
OUT(MARGIN)
100
1.18V
OUT
:
PART NUMBER
GRM32ER71H106K (10µF , 50V)
C3225X5RIC226M (22µF , 16V)
MARG0
RECOVERY
HIGH
HIGH
LOW
LOW
TIME (µs)
• V
14.8
14.8
15.2
34.4
26
27
25
30
35
35
39
37
70
70
OUT
• 10k
LOAD STEP
OUT
(A/µs)
LTM4612
3
3
3
3
3
3
3
3
3
3
3
3
3
3
to be margined,
MARGIN DOWN
NO MARGIN
MARGIN UP
NO MARGIN
MODE
11
(kΩ)
13.7
13.7
13.7
13.7
13.7
13.7
6.34
6.34
6.34
6.34
5.23
5.23
4.12
4.12
R
FB
4612fb