TPIC43T01, TPIC43T02

THREE-PHASE BRUSHLESS MOTOR RPM CONTROLLERS

SLIS098 – APRIL 2000

11

POST OFFICE BOX 655303

PRINCIPLES OF OPERATION

Table 1. FG Reference Frequency

EEPROM

EEPROM

FSEL

PRE-DIVIDER

TOTAL f(osc)

FG f(ref) @f(osc)

ADDR 1, BIT 1

ADDR 1, BIT 0

INPUT

DIVIDE BY

(osc)

DIVIDE-BY

1 MHZ

5 MHZ

10 MHZ

0

0

1

3

3072

326

1628

3256

0

0

0

6

6144

163

814

1628

0

1

1

4

4096

244

1221

2441

0

1

0

8

8192

122

610

1221

1

0

1

6

6144

163

814

1628

1

0

0

12

12,288

81

407

814

1

1

1

8

8192†

122

610

1221

1

1

0

16

16,384†

61

305

610

† Equals default value

An external resistor (RT) and capacitor (CT) must be connected from the respective RT and CT terminals to

GND to set the sampling frequency for the digital filter. Charge/discharge current at terminal CT will nominally

be

_

+

_

+

VDD

I(RT)

2I(RT)

IRT

RT

RT

V(RT) = 1 V

CT

CT

_

+

1.5

3.5

R

S

Q

Clock To

Digital Filter

4I(RT)

4:1

1:2

1:1

VDD

1 V Internal

Reference

I(RT)

Figure 5. Digital Filter Sampling Clock Generation