EVALPM6680 STMicroelectronics, EVALPM6680 Datasheet - Page 26
EVALPM6680
Manufacturer Part Number
EVALPM6680
Description
BOARD EVALUATION FOR PM6680
Manufacturer
STMicroelectronics
Datasheet
1.PM6680TR.pdf
(49 pages)
Specifications of EVALPM6680
Mfg Application Notes
PM6680 Eval Kit, AN2566 App Note
Main Purpose
DC/DC, Step Down with LDO
Outputs And Type
3, Non-Isolated
Power - Output
13.25W
Voltage - Output
1.05V, 1.5V, 5V
Current - Output
5A, 5A, 100mA
Voltage - Input
6 ~ 28V
Regulator Topology
Buck
Frequency - Switching
200kHz, 300kHz
Board Type
Fully Populated
Utilized Ic / Part
PM6680
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Other names
497-6241
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Device description
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Figure 32. No audible skip mode
The low side switch is turned on until the output voltage crosses about Vreg+1 %. Then the
high side MOSFET is turned on for a fixed on time period. Afterwards the low side switch is
enabled until the inductor current reaches the zero-crossing threshold. This keeps the
switching frequency higher than 33 kHz. As a consequence of the control, the regulated
voltage can be slightly higher than Vreg (up to 1 %).
If, due to the load, the frequency is higher than 33 kHz, the device works like in skip mode.
No-audible skip mode reduces audio frequency noise that may occur in pulse skip mode at
very light loads, keeping the efficiency higher than in PWM mode.
Current limit
The current-limit circuit employs a "valley" current-sensing algorithm. During the conduction
time of the low side MOSFET the current flowing through it is sensed. The current-sensing
element is the low side MOSFET on-resistance (
Figure 33. RDSON sensing technique
Inductor current
0
Low side
No audible skip mode
HS
LS
∼30us
RDS
Rcsense
on
Figure 33
HGATE
CSENSE
PHASE
LGATE
).
Time
PM6680