ATA6830_05 Datasheet, PDF (4/24 Pages) ATMEL Corporation – INTELLIGENT STEPPER MOTOR DRIVER

3. Functional Description
3.1 Analog Part
Figure 3-1. Analog Blocks
VBAT
VDD
Supply
Oscillator
Bias
Generator
Bandgap
Voltage
Regulator
Voltage Temperature
Supervisor Supervisor
Bias
Voltage Levels
Temperature Levels
Clock
Reset
COS
RSET
AGND
VSS
The circuit contains an integrated 5V regulator to supply the internal logic and analog circuit
blocks. The regulator uses an adjusted bandgap as voltage reference. Also all other parts that
require an excellent voltage reference, such as the voltage monitoring block refer to the
bandgap.
The bias generator derives its accurate currents from an external reference resistor. The oscilla-
tor is used for clocking the digital system. All timings like the baud rate, the step duration and the
chopper frequency are determined from it. An external capacitor is used for generating the
frequency.
The voltage monitoring enables the circuit to drive the stepping motor at different battery voltage
levels. According to the battery voltage the stepping motor will be accelerated to a maximum
step velocity. In case of under or over voltage the motor will shut off. A temperature monitoring is
used for shut off at overtemperature conditions and current boost in case of low temperature.
4 ATA6830
4575D–BCD–09/05