PM6680 STMicroelectronics, PM6680 Datasheet - Page 40

• Manufacturer Part Number: PM6680
• Description: IC CTRLR DUAL STEP DOWN 32VFQFPN
• Manufacturer: STMicroelectronics

Specifications of PM6680

• Applications: Controller, Notebook Power System
• Voltage - Input: 6 ~ 28 V
• Number Of Outputs: 2
• Voltage - Output: 0.9 ~ 5.5 V
• Operating Temperature: 0°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 32-VFQFN, 32-VFQFPN
• Output Voltage: 5 V, 0.9 V to 5.5 V, 0.9 V to 3.3 V
• Output Current: 0.33 A
• Input Voltage: 5.5 V to 28 V
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 10 C
• For Use With: 497-6379 - BOARD EVALUATION FOR PM6680A497-6378 - BOARD EVALUATION FOR PM6680497-6425 - BOARD EVAL BASED ON PM6680A
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Device description
7.13.7
40/49
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.36).
Other parts design
●
Figure 38. VIN pin filter
●
INT
VIN filter
A VIN pin low pass filter is suggested to reduce switching noise. The low pass filter is
shown in the next figure:
Typical components values are: R = 3.9 Ω and C = 4.7 uF.
VCC filter
A VCC low pass filter helps to reject switching commutations noise:
= 1 kΩ by eq.27, 28. C = 5.6 nF by Eq.34. Then R = 36 kΩ (eq.35) and R1 = 3 kΩ
ESR
SW
= 12mW. We choose C
= 290 kHz, L = 2.5 uH, C
Input
voltage
R
R
R
C
C
1
=
R
INT
R
=
R
×
R
−
1
= 1nF by equations 30, 33 and C
1
out
⎛
⎜ ⎜
⎝
ESR
0
0
C
C
0
0
L
= 330 uF with R
p
p
×
×
×
F
F
π
π
1
1
C
×
×
f
f
Z
Z
V
V
⎞
⎟ ⎟
⎠
I
I
N
N
out
≈
12 mΩ.
filt
= 47 pF,
PM6680