PM6681A STMicroelectronics, PM6681A Datasheet - Page 40

• Manufacturer Part Number: PM6681A
• Description: Dual synchronous step down controller with adjustable LDO
• Manufacturer: STMicroelectronics

Design guidelines
9.8.2
9.8.3
9.8.4
40/47
Ipeak = 2.5 A + 0.58 A = 3.08 A
OUT2 : I
We choose standard value L = 4.7 µH.
∆I
I
I
Output capacitor selection
We would like to have an output ripple smaller than 25 mV.
OUT1: POSCAP 4TPE150MI
OUT2: POSCAP 6TPE220M
Power MOSFETs
OUT1:High side: STS5NF60L
OUT2:High side: STS5NF60L
Low side: STS7NF60L
Current limit
OUT1:
(Let's assume the maximum temperature T
OUT2:
LRMS
peak
L(max)
= 2.5 A + 0.443 A = 2.943 A
= 2.513 A
Low side: STS7NF60L
= 0.89 A @ V
LOAD
= 2.5 A, 35 % ripple current.
IN
= 24 V.
I
I
Lvalley
Lvalley
L
R
=
CSENSE
(min)
(min)
425
1
KHz
8 .
=
=
≡
V
I
I
LOAD
LOAD
100
⋅
. 4
⋅
(
24
24
12
µ
(max)
V
V
(max)
max
A
A
⋅
−
. 0
⋅
1
16
= 75 °C in R
8 .
35
−
.
−
) V
25
∆
⋅
∆
2
I
m
L
I
5 .
L
(min)
2
Ω
(min)
2
≈
≈
. 4
670
=
76
DS(on)
=
. 4
µ
4
Ω
12
H
2 .
A
A
calculation)
PM6681A