STEVAL-ISA053V1 STMicroelectronics, STEVAL-ISA053V1 Datasheet - Page 26

• Manufacturer Part Number: STEVAL-ISA053V1
• Description: BOARD EVALUATION FOR PM6680
• Manufacturer: STMicroelectronics
• Type: DC/DC Switching Converters, Regulators & Controllersr

Specifications of STEVAL-ISA053V1

• Design Resources: STEVAL-ISA053V1 Gerber Files PM6680 Eval Kit Schematic STEVAL-ISA053V1 Bill of Material
• Main Purpose: DC/DC, Step Down with LDO
• Outputs And Type: 3, Non-Isolated
• 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
• Input Voltage: 6 V to 28 V
• Output Voltage: 5 V
• Product: Power Management Modules
• Silicon Manufacturer: ST Micro
• Silicon Core Number: PM6680
• Kit Application Type: Power Management - Voltage Regulator
• Application Sub Type: Step Down DC/DC Controller
• Kit Contents: Board
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: PM6680
• Other names: 497-6378

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