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STMicroelectronics Electronic Components Datasheet

L6256 Datasheet

12V COMBO

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L6256 pdf
L6256
12V COMBO
DESCRIPTION
The 12 Volt Combo chip is a combination spindle
motor driver, voice coil driver and D/A converter.
The part can be used in,application like HDD.
The VCM amplifiers drive a low impedance coil
and are set up to accept RC compensation, which
allows a wide bandwidth with absolute minimum
phase lag. The sense resistor/amplifier arrange-
ment allows full current loop operation. The loop
gain is changeable by attenuating the VCM DAC
voltage amplitude in cascadable stages.
The Spindle driver is a PWM only voltage loop
with power supply feedforward, driving a 3 phase
sensorless brushless DC motor. Since it uses
PWM operation at full run speed, it has output
slew rate control during start and run modes.
There is an inductive clamp circuit to limit flyback
voltage transients across the supply voltage dur-
ing motor phase changes and during the braking
sequence. Only the 2 phase or bipolar commuta-
tion pattern is produced by the internal commuta-
tion circuitry. A commutation register allows arbi-
Figure 1. Block Diagram
PLCC44
ORDERING NUMBER: L6256
trary winding sequencing during certain opera-
tions. Internal protection against crossover
spikes is built in.
3 phase or tripolar commutation can be supported
in software during start by writing a commutation
pattern directly to the preload register.
Tripolar operation requires that more than two
phase drivers contribute current simultaneously.
The current limit circuitry reflects this and allows
33% higher current limit, which produces nearly
CP_OUT
CP_CAP
18
19
33
H_VPWR
VDD
VCC
nPOR
POR_RC
PARK
34
15
10
9
27
13
SCLK
SDIO
CSELB
14
28
BYPASSC 16
CHARGE
PUMP
DAC
32
IO_VC
31
I_VC
26
A_IN
30
A_OUT B_OUT
25 23
VCM CLASS AB
DRIVERS
VPWR
2
UV
DETECT
POR
10 BIT
DAC
VCM
COMMAND
CHANNEL
VCM CONTROL
VCM
RETRACT
h_vpwr
VCM
LOGIC
THERMAL
-
+
A
AMP
PWR GND
-
+
h_vpwr
B
AMP
CLK
SYNC
SERIAL INTERFACE
3
BANDGAP
VOLTAGE
REFERENCE
CURRENT
SOURCES
SPINDLE LOGIC
SPINDLE SEQUENCER
BRAKE
DELAY
COUNTER
DYNAMIC
CLAMPING
SPINDLE DRIVERS
ANALOG
TEST MUX
24
SYNC
CLAMP
3
QDRIVE
VREG_IN
CUR_IN
20
21
22
3.3V LINEAR
REGULATOR
6,7,17,29,39,40
FEEDFORWARD
COMPENSATION
upper
lower
PRE-DRIVERS
8 11
R_ PWM_
SLEW IN
36 37 5
PWM_ FF_ SP_
DC COMP CLK
BEMF SENSING
ZERO CROSSING
DETECTION
CURRENT
LIMIT
SENSING
38 12
35
SH_ BEMF_ REF_
OUT DET
IN
44
SP_
G2
4
SP_
G1
24
VC_PWR
2
SP_P1
42
SP_P2
43
SP_A
1
SP_B
3
SP_C
41
C_TAP
D97IN571
December 1997
1/28


STMicroelectronics Electronic Components Datasheet

L6256 Datasheet

12V COMBO

No Preview Available !

L6256 pdf
L6256
DESCRIPTION (Continued)
constant torque. This is a very high power dissi-
pation mode, meant only for momentary opera-
tion in unusual circumstances.
Spindown during a power failure uses the back
EMF voltage generated by the spindle motor to
provide power to the VCM amplifier. The Spindle
motor coasts during the Brake Delay time to allow
time to park the head actuator. The park circuit is
a constant voltage circuit settable externally.
After the head is parked, braking commences.
The brake operates by shorting all 3 windings.
The spindle output stages stay on as long as is
OPERATING CONDITIONS
VCC = 4.5 to 5.5V
Vdd = 10.8 to 13.2V
0°C < Tamb < 70°C.
required to bring the motor to a complete stop,
even if no power is applied to the part.
A Power On Reset (POR) function provides pulse
stretching for the bidirectional POR\ bus, to en-
sure that the processor and clocks are at running
speed before allowing them to function.
5 volt and 12 volt pins are used directly for the un-
dervoltage detect circuit.
This allows direct use internally of both supplies.
Voltage monitor margining is supported.
An external 3.3V linear regulator is provided and
tied into the POR circuit.
ABSOLUTE MAXIMUM RATINGS
Symbol
VPWR
VPVR
Vdd
VCC
I_VCM, Aout
Logic I/O, SH_Out, PWM_DC
All other pins
Tstg
(1) Limited by chip clamp voltage.
Parameter
Normal Operating Voltage
Inductive Clamp Voltage @ 2mH, 1.6A, 3% Duty Cycle
Storage Ambient Temperature
ESD capability
Value
15
<20
15
6.4
-2 to VPWR +2V
-0.3 to VCC +0.3
-0.3 to VPWR +0.3V
-65 to +150
±2
Unit
V
V (1)
V
V
°C
kV
PIN CONNECTION
2/28
GND
R_SLEW
POR_RC
nPOR
PWM_IN
BEMF_DET
SCLK
SDIO
VCC
BYPASSC
5V_GND
6 5 4 3 2 1 44 43 42 41 40
7 39
8 38
9 37
10 36
11 35
12 34
13 33
14 32
15 31
16 30
17 29
GND
SH_OUT
FF_COMP
PWM_DC
REF_IN
VDD
H_VPWR
DAC
IO_VC
A_IN
GND
18 19 20 21 22 23 24 25 26 27 28
D97IN572


Part Number L6256
Description 12V COMBO
Maker STMicroelectronics
Total Page 28 Pages
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