PM6686 STMicroelectronics, PM6686 Datasheet - Page 27

• Manufacturer Part Number: PM6686
• Description: Dual Step-down Controller With Adjustable Voltages, Adjustable Ldo And Auxiliary Charge Pump Controller For Notebook
• Manufacturer: STMicroelectronics

PM6686
The COT architecture uses a minimum off-time (T
sense on the synchronous switch and to allow the charge of the bootstrap capacitor. A
minimum on-time is also introduced to assure the start-up sequence.
An adaptive anti-cross conduction algorithm avoids current paths between V
during switching transition.
The PM6686 has three different operation modes selectable with SKIP pin: forced PWM
(PWM), pulse SKIP (SKIP) and non audible pulse SKIP (NA SKIP). The following
paragraphs explain in details the different features of these operation modes.
Table 9.
Figure 46. Constant on time block diagram
OU T
ILIM
VIN
Control pin
SKIP
Operative mode configurations
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PHASE
Reference
Voltage
+
0,8V
-
Comparator
Comparator
+
PWM
-
Z .C.
Doc ID 15281 Rev 4
+
-
-
VREF2 or floating
connected to
T off min
Control pin
generator
S
R
CL R
SET
T on
GND
VCC
Q
Q
S
R
C LR
SET
OFFMIN
Q
Q
) to allow inductor valley current
Shifter
Level
-
+
-
LS Driver
-
Operation mode
PVCC
HS Driver
0,25V
+
-
Device description
NA SKIP
PWM
SKIP
0,5V
IN
and GND
PH ASE
LGATE
HGAT E
BOOT
PGND
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