PM6680ATR STMicroelectronics, PM6680ATR Datasheet - Page 32

• Manufacturer Part Number: PM6680ATR
• Description: IC CTRLR DUAL STEP DOWN 32VFQFPN
• Manufacturer: STMicroelectronics

Specifications of PM6680ATR

• Applications: Controller, Embedded Computer System
• Voltage - Input: 6 ~ 36 V
• Number Of Outputs: 2
• Voltage - Output: 0.9 ~ 5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 32-VFQFN, 32-VFQFPN
• 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
• Other names: 497-6896-2; PM6680ATR

Design guidelines
9.4
32/48
Table 11.
Input capacitors selection
In a buck topology converter the current that flows into the input capacitor is a pulsed current
with zero average value. The input RMS current of the two switching sections can be roughly
estimated as follows:
Equation 17
Where D1, D2 are the duty cycles and I1, I2 are the maximum load currents of the two
sections.
Input capacitor should be chosen with an RMS rated current higher than the maximum RMS
current given by both sections.
Tantalum capacitors are good in term of low ESR and small size, but they occasionally can
burn out if subjected to very high current during the charge. Ceramic capacitors have
usually a higher RMS current rating with smaller size and they remain the best choice.
Below there is a list of some ceramic capacitor manufacturers.
Table 12.
Manufacturer
PANASONIC
SANYO
TAYIO YUDEN
TAYIO YUDEN
Manufacturer
Output capacitor manufacturer
Input capacitor manufacturer
POSCAP TPB, TPD,
SPCAP UD, UE
I
CinRMS
Series
TPE
UMK325BJ106KM-T
GMK325BJ106MN
=
Series
D
1
×
I
1
2
Capacitor value
×
1 (
100 to 470
100 to 470
−
(uF)
D
1
)
Capacitor value (uF)
+
D
2
×
I
2
2
Rated voltage (V) ESR max (mΩ)
10
10
×
1 (
2.5 to 6.3
−
2 to 6.3
D
2
)
Rated voltage (V)
50
35
12 to 65
7 to 18
PM6680A