L6238 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'L6238' PDF : 35 Pages View PDF
L6238
GENERAL DESCRIPTION
The L6238 is an integrated circuit that will be
used to commutate and speed control a 3-Phase,
8-pole, brushless, DC motor. The primary applica-
tion is for disk drive spindle motors. This I.C. has
the following features:
No Motor Hall Effect Sensors are required for
commutation or speed control. Timing informa-
tion is determined from the Bemf voltage of the
undriven motor terminal.
On-board Speed Control via a Phase Locked
Loop that accepts a once-per-rev reference
frequency and locks the motor to that fre-
quency. The L6238 can accomodate a wide
range of speeds.
The L6238 achieves Spindle Synchronization
by locking to a once-per-rev reference that is
common to multiple drives. The L6238 has a
multiplexer that enhances the versatility of the
controller. This first multiplexer selects either
internal feedback, (generated by the Bemf of
the motor), or external feedback (embedded
index).
An External P-Channel FET can be connected
to the FET can be connected to the FET
Bridge for Higher Power Applications.
In this configuration, the internal DMOS drivers
are sequenced in full conduction state and the
external PFET is the linear control element. An
internal inverting buffer from the output of the
OTA controls the conduction of the EXT PFET.
An internal Virtual Center Tap is used if the
motor center tap is not connected.
The motor Current Limit can be set by an ex-
ternal resistor divider.
A Serial Port is included so that I/O can be
done with a minimum of pins. Key control and
status lines are also bonded out to achieve a
Minimum Configuration without using the Serial
Port.
Programmable Functions include Phase
Switch Timing Optimization for motor effi-
ciency, Speed Lock Threshold, Auto-Start or
mP Supervised Spinup, and output current lim-
iting gain.
Energy Recovery Mode for Head Retraction,
followed by Dynamic Braking Mode.
Logic signals are CMOS Compatible.
Stuck Rotor and Backward Rotation detection.
Automatic Thermal Shutdown with early warn-
ing bit available in the status register
PIN FUNCTIONS
N.
Name
I/O
1
OUTPUT B
I/O
2
SPIN SENSE
O
3
BRAKE DELAY
I
4
Rsense
O
5 CHARGE PUMP 2 I
6, 7,
GROUND
I
17, 29,
39, 40
8 CHARGE PUMP 1 I
9 CHARGE PUMP 3 I
10
OUTPUT A
I/O
11, 42
Vp ower
I
12
Vanalog
I
13
SER PORT
I
DISABLE
14 SER DATA R/W
I
15
SER STROBE
I
16 SER PORT CLK
I
18
SER DATA I/O
I/O
19
EXT/IN T
I
20 FREF ENABLE
I
21
LINEAR
I
22
OUTPUT
I
ENABLE
Function
DMOS Half Bridge Output and Input B for Bemf sensing.
Toggless at each Zero Crossing of the Bemf.
Energy Recovery time constant, defined by external R-C to ground.
Outputs A+B connections for the Motor Current Sense Resistor to ground
Negative Terminal of Pump Capacitor.
Ground terminals.
Positive terminal of Pump Capacitor.
Positive terminal of Storage Capacitor.
DMOS Half Bridge Output and Input A for Bemf sensing.
Supplies the voltage for the Power Section.
12V supply.
Input for tri-stating the serial port.
Selects Serial Data Read or Write Function.
Dtat Strobe Input.
Clock for Serial Data Control.
Data stream Input/Output for Control/Status Registers.
Selects thr Internal BEMF Zero Crossing or an External Source as Feedback
Frequency for te PLL.
A zero on this pin passes the PLL Fref signal to the Freq/phase detector.
This input should be grounded or left unconnected.
Tristates Power Output Stage when a logic zero.
3/35
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