PM6680 STMicroelectronics, PM6680 Datasheet - Page 33

• 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

PM6680
7.13.3
Equation 14
If hard saturation inductors are used, the inductor saturation current should be much greater
than the maximum inductor peak current I
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 R
rather than on the capacitor value C
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 ∆I
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
page 37
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
TDK
).
Inductor manufacturer
RLF12560
SER1360
Series
MLC
RIPPLEout
∆
I
Inductor value (uH)
L
Ipeak
(max)
V
0.7 to 4.5
is given by:
out
1 to 10
RIPPLEout
=
1 to 8
=
.
I
Section 7.13.6: Closing the integrator loop on
LOAD
V
IN
peak
max
(max)
f
sw
=
:
−
R
×
V
L
out
+
OUT
RMS current (A)
×
∆
I
13.6 to 17.3
∆
L
7.5 to 14.4
×
I
(max)
6 to 9.5
L
2
V
V
IN
OUT
max
out
Saturation current (A)
and the voltage rating
Device description
7.5 to 18.5
11.5 to 26
7 to 31
L
.
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