FAN5059MX Fairchild Semiconductor, FAN5059MX Datasheet - Page 16

• Manufacturer Part Number: FAN5059MX
• Description: IC CTRLR DC/DC PROG SYNC 24SOIC
• Manufacturer: Fairchild Semiconductor

Specifications of FAN5059MX

• Applications: Controller, VRM8.5
• Voltage - Input: 5V
• Number Of Outputs: 1
• Voltage - Output: 1.3 ~ 3.5 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 24-SOIC (7.5mm Width)
• Output Current: 18 A
• Input Voltage: 5 V
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: FAN5059MXTR; FAN5059MX_NL; FAN5059MX_NLTR; FAN5059MX_NLTR

FAN5059
Appendix
Worst-Case Formulae for the Calculation of
Cin, Cout , R5, R7 and Roffset
Figure 1 only)
The following formulae design the FAN5059 for worst-case
operation, including initial tolerance and temperature dependence
of all of the IC parameters (initial setpoint, reference tolerance
and tempco, internal droop impedance, current sensor gain),
the initial tolerance and temperature dependence of the MOSFET,
and the ESR of the capacitors. The following information
must be provided:
V
|V
V
|V
I
V
V
I
(2A for the Sanyo parts shown in this datasheet);
R
for MOSFET sensing, including temperature); and
ESR, the ESR of the output capacitors, per cap (44m for
the Sanyo parts shown in this datasheet).
16
O
rms
R
in
D
S+
T+
nom
S-
T-
, the maximum output current;
, the resistance of the current sensor (usually the MOSFET);
, the input voltage (typically 5V);
D
, the ripple current rating of the input capacitors, per cap
|, the absolute value of the negative transient voltage limit;
, the value of the positive static voltage limit;
|, the absolute value of the negative static voltage limit;
, the value of the positive transient voltage limit;
, the tolerance of the current sensor (usually about 67%
, the nominal output voltage;
R
C
R5 =
offset
in
=
R7
14400 * I
18 * (V
=
IO
=
*
V
S+
1.01 * V
I
O
S+
– .024 * V
* R
V
O
V
+ V
nom
* R
45 * 10
in
D
I
* (1 + R
D
rms
nom
S-
* (1 + R
– .024 * V
–
nom
-6
(Circuits similar to
V
V
D
nom
in
)
D
* 1K
) *1.1
nom
2
)
The value of R7 must be 8.3K . If a greater value is calcu-
lated, R
Number of capacitors needed for C
Example: Suppose that the static limits are +89mV/-79mV,
transient limits are ±134mV, current I is 14.2A, and the
nominal voltage is 2.000V, using MOSFET current sensing.
We have V
= 14.2, V
Since Y > X, we choose Y, and round up to find we need 7
capacitors for C
A detailed explanation of this calculation may be found in
Applications Bulletin AB-24.
R5
Y
or
C
in
=
=
=
14.2
X
R
D
0.134 – 0.089
offset
nom
R7
14400 * 14.2 * 0.020 * (1 + 0.67) * 1.1
=
must be reduced.
Y
S+
18 * (0.089 + 0.079 – .024 * 2.000)
*
=
= 2.000, and R
=
= 0.089, |V
=
0.134 + 0.089 – .024 * 2.00
OUT
0.089 – .024 * 2.000
14.2 * 0.010 * (1 + 0.67)
X =
V
2.000
T+
0.044 * 14.2
.
1.01 * 2.000
5
0.044 * 14.2
– V
2
45 * 10
+
S-
S+
–
V
14400 * 14.2 * 0.020
| = 0.079, V
T-
+
18 * 3640 * 1.1
2.000
D
-6
5
= 1.67. We calculate:
+ V
ESR * I
ESR * I
PRODUCT SPECIFICATION
out
14400 * I
18 * R5 * 1.1
S+
2
= the greater of:
T+
– .024 * V
*1000
=
= |V
REV. 1.0.4 8/14/03
O
=
=
O
3.47
5.25K
3.57
O
T-
=
* R
| = 0.134, I
20.3
=
D
3.48K
nom
=
4 caps
6.14
O