PM6680ATR STMicroelectronics, PM6680ATR Datasheet - Page 19

IC CTRLR DUAL STEP DOWN 32VFQFPN

PM6680ATR

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

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

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
PM6680ATR
Manufacturer:
STMicroelectronics
Quantity:
10 000
Part Number:
PM6680ATR
Manufacturer:
ST
0
PM6680A
Figure 28. Constant ON time PWM control
The duty cycle of the buck converter in steady state is:
Equation 2
The PWM control works at a nearly fixed frequency f
Equation 3
As mentioned the steady state switching frequency is theoretically independent from input
voltage and from output voltage.
Actually the frequency depends on parasitic voltage drops that are present during the
charging path(high side switch resistance, inductor resistance(DCR)) and discharging
path(low side switch resistance, DCR).
As a result the switching frequency increases as a function of the load current.
Standard switching frequency values can be selected for both sections by pin FSEL as
shown in the following table:
Table 6.
FSEL = VREF
FSEL = LDO5
FSEL = GND
FSEL pin selection: typical switching frequency
Fsw@OUT1 = 3.3 V (kHz)
f
SW
195
295
390
=
------------------------------ -
K
on
D
V
--------------
=
V
×
OUT
IN
V
--------------
V
--------------
V
V
OUT
OUT
IN
IN
=
1 K
SW
:
on
Fsw@OUT2 = 1.8 V (kHz)
Device description
335
440
600
19/48

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