STEVAL-ISA052V1 STMicroelectronics, STEVAL-ISA052V1 Datasheet - Page 29

• Manufacturer Part Number: STEVAL-ISA052V1
• Description: KIT EVAL PM6675S HE CTLR 2A REG
• Manufacturer: STMicroelectronics

Specifications of STEVAL-ISA052V1

• Main Purpose: DC/DC, Step Down with LDO
• Outputs And Type: 2, Non-Isolated
• Voltage - Output: 1.5V, 0.6 ~ 3.3V
• Current - Output: 10A, 2A
• Voltage - Input: 4.5 ~ 28 V
• Regulator Topology: Buck
• Board Type: Fully Populated
• Utilized Ic / Part: PM6675
• Product: Power Management Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Frequency - Switching: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 497-8426

PM6675S
No-audible pulse-skip mode
Some audio-noise sensitive applications cannot accept the switching frequency to enter the
audible range as it is possible in Pulse-Skip mode with very light loads. For this reason, the
PM6675S implements an additional feature to maintain a minimum switching frequency of
33kHz despite a slight efficiency loss. At very light load conditions, if any switching cycle has
taken place within 30µs (typ.) since the last one (because of the output voltage is still higher
than the reference), a No-Audible Pulse-Skip cycle begins. The low-side MOSFET is turned
on and the output is driven to fall until the reference point has been crossed. Then, the high-
side switch is turned on for a T
is enabled until the inductor current reaches the zero-crossing threshold (see
Figure 38.
For frequencies higher than 33 kHz (due to heavier loads) the device works in the same way
as in Pulse-Skip mode. It is important to notice that in both Pulse-Skip and No-Audible
Pulse-Skip modes, the switching frequency changes not only with the load but also with the
input voltage.
Inductor
current
Output
voltage
V
reg
Inductor current and output voltage at light load with non-audible pulse-skip
T
ON
T
OFF
ON
T
MAX
T
period and, once it has expired, the synchronous rectifier
IDLE
Device description
Figure 38
t
29/53
).