STEVAL-ISA052V2 STMicroelectronics, STEVAL-ISA052V2 Datasheet - Page 28

• Manufacturer Part Number: STEVAL-ISA052V2
• Description: BOARD EVAL BASED ON PM6675A
• Manufacturer: STMicroelectronics
• Type: DC/DC Switching Converters, Regulators & Controllersr

Specifications of STEVAL-ISA052V2

• Design Resources: STEVAL-ISA052V2 Gerber Files STEVAL-ISA052V2 Schematic STEVAL-ISA052V2 Bill of Material
• Main Purpose: DC/DC, Step Down with LDO
• Outputs And Type: 2, Non-Isolated
• Voltage - Output: 1.5V, 0.6 ~ 3.3V
• Voltage - Input: 4.5 ~ 36 V
• Regulator Topology: Buck
• Board Type: Fully Populated
• Utilized Ic / Part: PM6675AS
• Input Voltage: 4.5 V to 36 V
• Output Voltage: 1.5 V
• Product: Power Management Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Power - Output: -
• Frequency - Switching: -
• Lead Free Status / Rohs Status: Supplier Unconfirmed
• For Use With/related Products: PM6675AS
• Other names: 497-8413

Device description
7.1.6
28/48
POR, UVLO and soft-start
The PM6675AS automatically performs an internal startup sequence during the rising
phase of the analog supply of the device (AVCC). The switching controller remains in a
stand-by state until AVCC crosses the upper UVLO threshold (4.25 V typ.), keeping active
the internal discharge MOSFETs (only if AVCC > 1 V).
The soft-start allows a gradual increase of the internal current limit threshold during startup
reducing the input/output surge currents. At the beginning of start-up, the PM6675AS
current limit is set to 25 % of nominal value and the under voltage protection is disabled.
Then, the current limit threshold is sequentially brought to 100 % in four steps of
approximately 750 µs (figure 13).
Figure 31. Soft-start waveforms
After a fixed 3 ms total time, the soft-start finishes and UVP is released: if the output voltage
doesn't reach the under voltage lower threshold within soft-start duration, the UVP condition
is detected; the device performs a soft end and latches off. Depending on the load
conditions, the inductor current may or may not reach the nominal value of the current limit
(
Figure 32 on page 29
Switching output
shows two examples).
Current limit threshold
SWEN
Time
PM6675AS