L6238S View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'L6238S' PDF : 31 Pages View PDF
Figure 3-1: Align+Go
RUN/BRAKE
SEQUENCER
*0.711s
ALIGNMENT
DOUBLE INCREMENTS
*2.133s
L6238S
GO
AOUT
1 10V
BOUT
2 10V
COUT
3 10V
STATE 2
A=HIGH
B=FLOAT
C=LOW
STATE 4
A=LOW
B=HIGH
C=FLOAT
STATE 6
A=FLOAT
B=LOW
C=HIGH
* FALIGN=90Hz
500ms/DIV
D95IN314
2) Closed Loop Start-Up - The Bemf voltage
zerocrossings provide timing information so that
the motor can be accelerated to steady state
speed.
3) Steady-State Operation - The Bemf voltage
zero-crossings provide timing information for pre-
cision speed control.
The L6238S contains features that offer flexible
control over the start-up procedure. Either the on-
board Auto-Start Algorithm can be used to control
the start-up sequence or more sophisticated ex-
tenal start-up algorithms can be developed using
the Serial Port and key control/sense functions
brought out to pins.
3.2 Auto-Start Algorithm
When initially powered up, the controller defaults
to the internal AutoStart Mode. When Run/Brake
is low, the L6238S is in brake mode, and the
Auto-Start Algorithm is reset. In the brake mode,
all of the lower DMOS drivers are ON, and the up-
per drivers are OFF.
The Auto-Start Algorithm is based on an Align &
Go approach and can be visualized by referring to
Figure 3-1. Shown are the Run/Brake control sig-
nals, sequencer function, and the three output
voltage waveforms.
Referring to figure 3-1, the following is the se-
quence of events during Auto-Start:
With Output Enable = 1, Run/Brake = 0
- State Machine is set to State 1 with the drivers
Trisatted.
Alignment Phase (1)
Run/Brake = 1
- Output Stage is sequenced to State 2 and the
drivers energized with OUTPUT A high and
OUTPUT C low for 64/Falign seconds.
Alignment Phase (2)
- Output Stage is double sequenced to State 4
with OUTPUT B high and OUTPUT A low for
13/31
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