PM6680A STMicroelectronics, PM6680A Datasheet - Page 31

• Manufacturer Part Number: PM6680A
• Description: IC CTLR DUAL SYNC STDN 5X5VFQFPN
• Manufacturer: STMicroelectronics

Specifications of PM6680A

• 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

PM6680A
9.3
Equation 14
If hard saturation inductors are used, the inductor saturation current should be much greater
than the maximum inductor peak current Ipeak:
Equation 15
Using soft saturation inductors it's possible to choose inductors with saturation current limit
nearly to Ipeak.
Below there is a list of some inductor manufacturers.
Table 10.
Output capacitor
The selection of the output capacitor is based on the ESR value Rout and the voltage rating
rather than on the capacitor value Cout.
The output capacitor has to satisfy the output voltage ripple requirements. Lower inductor
value can reduce the size of the choke but increases the inductor current ripple ∆IL.
Since the voltage ripple V
Equation 16
A low ESR capacitor is required to reduce the output voltage ripple. Switching sections can
work correctly even with 20 mV output ripple.
However, to reduce jitter noise between the two switching sections it's preferable to work
with an output voltage ripple greater than 30 mV. If lower output ripple is required, a further
compensation network is needed (see Closing the integrator loop paragraph).
Finally the output capacitor choice deeply impacts on the load transient response (see Load
transient response paragraph). Below there is a list of some capacitor manufacturers.
Manufacturer
COILCRAFT
COILCRAFT
WURTH
Inductor manufacturer
MSS1038
MSS7341
Series
TPC
RIPPLEout
∆
I
Ipeak
L
(max)
Inductor value
is given by:
V
RIPPLEout
=
1 to 22 µH
=
1.5 to 22
3.3 to 22
I
LOAD
(uH)
V
IN
max
(max)
f
sw
=
−
R
×
V
L
out
+
OUT
×
∆
I
∆
L
×
RMS current
I
(max)
L
2.85 to 7.85
2
1.7 to 3.95
V
V
2.7 to 8
IN
OUT
max
(A)
Design guidelines
Saturation current
2.9 to 8.30
1.3 to 3.5
2.6 to 9.5
(A)
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