FAN5019MTC Fairchild Semiconductor, FAN5019MTC Datasheet - Page 25

• Manufacturer Part Number: FAN5019MTC
• Description: DC/DC Switching Controllers PWM 4 phases contrlr
• Manufacturer: Fairchild Semiconductor

Specifications of FAN5019MTC

• Number Of Outputs: 4
• Input Voltage: 10.2 V to 13.8 V
• Mounting Style: SMD/SMT
• Package / Case: TSSOP-28
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: 0 C

PRODUCT SPECIFICATION
Choosing the closest standard values for these components
yields: C
33pF.
C
In continuous inductor-current mode, the source current of
the high-side MOSFET is approximately a square wave with
a duty ratio equal to n (V
nth of the maximum output current. To prevent large voltage
transients, a low ESR input capacitor sized for the maximum
rms current must be used. The maximum rms capacitor cur-
rent is given by:
Figure 6. Typical Transient Response for Design Example
Note that the capacitor manufacturer’s ripple current ratings
are often based on only 2000 hours of life. This makes it
advisable to further derate the capacitor, or to choose a
capacitor rated at a higher temperature than required. Several
capacitors may be placed in parallel to meet size or height
requirements in the design. In this example, the input
capacitor bank is formed by three 2200µF, 16V Nichicon
capacitors with a ripple current rating of 3.5A each.
To reduce the input-current di/dt to below the recommended
maximum of 0.1A/µs, an additional small inductor (L > 1µH
@ 15A) should be inserted between the converter and the
supply bus. That inductor also acts as a filter between the
converter and the primary power source.
REV. 1.0.7 1/5/04
R
I
I
IN
CRMS
CRMS
CS
( 2
Selection and Input Current di/dt Reduction
NEW
. 0
D
A
)
125
= 390pF, R
R
I
O
CS
65
( 2
OLD
A
n
)
1
A
D
3
V
V
= 16.9k , C
OUT
NL
NL
1
. 0
1
125
/V
V
V
FLCOLD
FLHOT
IN
) and an amplitude of one-
1
B
10
= 1.5nF, and C
5 .
A
FB
(35)
(34)
=
Tuning Procedure for the FAN5019
DC Load line Setting
1.
2.
3.
4.
5.
6.
7.
8.
9.
Build circuit based on compensation values computed
from design spreadsheet.
Hook up DC load to circuit, turn on and verify opera-
tion. Also check for jitter at no-load and full-load.
Measure output voltage at no-load (V
within tolerance.
Measure output voltage at full-load cold (V
Let board soak for ~10 minutes at full-load and measure
output (V
couple of millivolts, adjust R
Equations 35 and 37.
Repeat Step 4 until cold and hot voltage measurements
remain the same.
Measure output voltage from no-load to full-load using
5 Amp steps. Compute the loadline slope for each
change and then average to get overall loadline slope
(R
If R
use the following to adjust the R
Repeat Steps 6 and 7 to check loadline and repeat
adjustments if necessary.
Once complete with DC loadline adjustment, do not
change R
R
100
PH
80
60
40
20
OMEAS
0
OMEAS
(
NEW
0
Figure 7. Efficiency vs. Output Current
)
).
PH
FLHOT
is off from R
R
, R
10
PH
CS1
(Circuit of Figure 5)
(
). If there is a change of more than a
OLD
, R
OUTPUT CURRENT (A)
)
20
CS2
R
OMEAS
O
R
, or R
O
by more than 0.05 m ,
30
CS1
TH
PH
and R
for rest of procedure.
40
values:
NL
CS2
). Verify it is
50
using
FLCOLD
FAN5019
(36)
60
).
25