L6245 Datasheet, PDF (5/15 Pages) STMicroelectronics – 5V HARD DISK DRIVE POWER COMBO

L6245
PIN DESCRIPTION (continued)
Pin Number Pin Name Pin Type
44
SYNTH_HALL
O
49, 50,
SPIN SENSE
A
58
1,2,3
46
PWM_OFFT
A
56
SLEW
A
51
S_COMP
A
Description
A TTL compatible signal that emulates one of the Hall signals.
SYNTH_HALL is an open drain output with an internal 20KΩ pull-up.
The current sensing resistors is connected from these pins to ground.
A parallel R-C from this pin to ground sets the PWM mode OFF time.
A resistor from this pin to ground sets the slew rate of the driver.
An R-C network from this pin to GND sets the spin driver
compensation.
VCM Driver and 8 bit D/A
Pin Number
8
9
21
14
23
Pin Name
VCM_DAC
VCM_CMD
VCM_COMP
VCM_RS1
VCM_RS2
Pin Type
O
I
A
A
A
13
VCM+
O
15
VCM-
O
20
OV_VO LT
O
19
OV_CUR
O
16
OV_SUM–
I
18
OV_SUM_OUT
O
Description
The output of an 8 bit D/A used to command the VCM driver.
VCM driver input command which is relative to V_REF.
An R-C network from this pin to ground compensates the VCM driver.
The high gain current sense resistor is attached from this pin to ground.
The low gain current sense resistor is connected from this pin to
VCM_RS1
One end of the load is attached to this pin (Positive).
The other end of the load is attached to this pin (Negative).
A voltage which is proportional to the voltage across the load,
referenced to V_REF.
A voltage which is proportional to the current through the load,
referenced to VREF.
Over-velocity summing op-amp inverting input.
Over-velocity summing op-amp output.
22
ISENSE
O
A voltage which is proportional to the current through the VCM load as
sensed by the sense resistor. This signal is enabled by setting bit 2 in
the VCM Control Register.
54
VCM_STRB
I
The 8 bit input to the VCM D/A is updated on the rising edge of
VCM_STRB.
Solenoid Pre-drivers and Power Down Sequencing
Pin Number
11,55,
63
Pin Name
V_RECIR
Pin Type
P
2
LOAD_SOL
O
1
UNLOAD_SOL
O
4
PD_SEQ_CAP
A
52
BRK_DLY
A
Description
Under normal conditions, power is supplied to various blocks via the
V_RECIR pin. When external power is removed, energy stored in the
rotating spindle is converted to a voltage which supplies the park circuit.
When a logic one is written to bit 3 of the VCM Control Register,
current is sourced from the LOAD_SOL pin. Otherwise, the pin is high
impedance.
When a logic one is written to bit 4 of the VCM Control Register,
current is sourced from the UNLOAD_SOL pin. Otherwise, the pin is
high impedance.
When power is removed, the charge stored on this capacitor keeps
selected blocks alive long enough to effect an orderly power down.
An external parallel RC network from this point to ground delays
activation of the dynamic brake after power is removed.
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