STPMIC25APQR datasheet(57/145 Pages) STMICROELECTRONICS

57 / 145 page

5.4.10.1

Frequency spreading for buck converters

Electromagnetic interference (EMI) is an issue prevalent to DC-DC converters, as these signals can cause

disturbances to the system at large.

There are many proposed solutions to mitigate EMI, but STPMIC25 is focused on spread spectrum frequency

modulation (SSFM). SSFM is a way to utilize PWM technology by randomly varying the switching frequency

within a set range of 10 to 20% centered at the desired average 2 MHz switching frequency. This works to

eliminate harsh and potentially disastrous peaks at the switching frequency.

5.5

Programming

5.5.1

I²C interface

The I²C interface works in slave mode. It supports both standard and fast modes with a data rate up to 400 Kb/s.

It also supports fast mode plus (Fm+) with a data rate up to 1 Mb/s that is a suitable frequency for DVS

operations.

5.5.1.1

Device ID

There is a device ID system to address the STPMIC25.

The address is stored in the NVM_I²C_ADDR_SHR[6:0] shadow register bit field. The hard coded I²C default

address defined in the NVM is 0x33.

Table 28. Device ID format

AddID6

AddID5

AddID4

AddID3

AddID2

AddID1

AddID0

R/W

5.5.1.2

Read/write operation

Each transaction is composed of a start condition followed by a packet number (8-bit long) representing either a

device ID plus R/W command, register address, or register data coming to/from the slave.

Table 28 An acknowledgment is needed after each packet. This acknowledgment is given by the receiver of the

packet. Transaction examples are given in Table 29 and Table 30. Multi-read and multi-write operations are

supported.

Table 29. Register address format

RegAdd7

RegAdd6

RegAdd5

RegAdd4

RegAdd3

RegAdd2

RegAdd1

RegAdd0

Table 30. Register data format

DATA7

DATA6

DATA5

DATA4

DATA3

DATA2

DATA1

DATA0

Figure 20. I²C read operation

STPMIC25

Feature descriptions

DS14278 - Rev 3

page 57/145

STPMIC25APQR Datasheet(PDF) 57 Page - STMicroelectronics

STPMIC25APQR Datasheet(HTML) 57 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL