EVALPM6680A STMicroelectronics, EVALPM6680A Datasheet - Page 38

• Manufacturer Part Number: EVALPM6680A
• Description: EVAL BOARD FOR PM6680A
• Manufacturer: STMicroelectronics

Specifications of EVALPM6680A

• Mfg Application Notes: PM6680A, AN2565 Appl Note
• Main Purpose: DC/DC, Step Down with LDO
• Outputs And Type: 3, Non-Isolated
• Power - Output: 10.5W
• Voltage - Output: 1.8V, 3.3V, 5V
• Current - Output: 2.5A, 2.5A, 100mA
• Voltage - Input: 6 ~ 36V
• Regulator Topology: Buck
• Frequency - Switching: 200kHz, 300kHz
• Board Type: Fully Populated
• Utilized Ic / Part: PM6680A
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6263

Design guidelines
38/48
Equation 30
where R
by the virtual ESR network RESR.
Moreover C
Equation 31
Where k is a free design parameter greater than 3 and determines the minimum integrator
capacitor value C
Equation 32
C must be selected as shown:
Equation 33
R must be chosen in order to have enough ripple voltage on integrator input:
Equation 34
R1 can be selected as follows:
Equation 35
Example:
OUT1=1.5 V, f
We design R
R
(eq.35).
INT
= 1 kΩ by eq.27, 28. C = 5.6 nF by Eq.34. Then R = 36 kΩ (eq.34) and R1 = 3 kΩ
TOT
INT
is the sum of the ESR of the output capacitor R
ESR
SW
must meet the following condition:
= 12 mΩ. We choose C
INT
= 290 kHz, L = 2.5 µH, Cout = 330 µF with Rout < 12 mΩ.
:
C
f
sw
INT
>
f
R
Z
>
k
1
=
×
2
=
R
f
π
2
C
Z
R
INT
π
×
=
R
=
>
×
×
⎛
⎜ ⎜
⎝
R
−
g
2
5
⎛
⎜ ⎜
⎝
= 1 nF by equations 30, 33 and Cfilt = 47 pF,
f
C
sw
k
ESR
m
π
C
C
×
out
×
L
1
C
×
×
−
C
×
×
INT
π
1
π
f
1
Z
R
out
C
×
×
k
⎞
⎟ ⎟
⎠
TOT
f
f
×
×
Z
Z
R
V
⎞
⎟ ⎟
⎠
Vr
OUT
TOT
out
and the equivalent ESR given
PM6680A