TPIC43T01, TPIC43T02

THREE-PHASE BRUSHLESS MOTOR RPM CONTROLLERS

SLIS098 – APRIL 2000

10

POST OFFICE BOX 655303

PRINCIPLES OF OPERATION

voltage regulator

1

circuitry.

oscillators

internal oscillator

The device generates an internal 5.8 MHz clock to supply a frequency input to internal control blocks as

presented in Figure 4. No external components are required.

5.8 MHz

Oscillator

÷ 32

Charge

Pump

ILIM/OCSD

Deglitch

Timer

8-Bit PWM

Generator

PWM, f

∼23 kHz

Watchdog

÷ 8

Gate Drive

Dead Time

Control

Integrator

181 kHz

∼ 45 kHz

Figure 4. 5.8 MHz Internal Oscillator Fanout

FG reference oscillator

The FG reference oscillator provides a clock to the FG frequency control section of the device. The oscillator

requires an external 5 to 10 MHz crystal to select the primary frequency. The user can alternatively input a 1

to 10 MHz signal from a signal generator to the OSC1 input to replace the external crystal. Two EEPROM bits

allow programming four different crystal oscillator divide-by values for controlling the FG reference frequency.

The FSEL pin provides an additional divide-by-2 for on-the-fly FG frequency (RPM) selection. Table 1 shows

the divide-by count and resulting FG reference frequency based on the two EEPROM bits (address 1, bits 0 –1)

and the FSEL pin input level.