PIN DESCRIPTION (continued)

Pin Number

Pin Name

Pin Type

Description

44

SYNTH_HALL

O

A TTL compatible signal that emulates one of the Hall signals.

SYNTH_HALL is an open drain output with an internal 20K

Ω pull-up.

49, 50,

58

SPIN SENSE

1,2,3

A

The current sensing resistors is connected from these pins to ground.

46

PWM_OFFT

A

A parallel R-C from this pin to ground sets the PWM mode OFF time.

56

SLEW

A

A resistor from this pin to ground sets the slew rate of the driver.

51

S_COMP

A

An R-C network from this pin to GND sets the spin driver

compensation.

VCM Driver and 8 bit D/A

Pin Number

Pin Name

Pin Type

Description

8

VCM_DAC

O

The output of an 8 bit D/A used to command the VCM driver.

9

VCM_CMD

I

21

VCM_COMP

A

An R-C network from this pin to ground compensates the VCM driver.

14

VCM_RS1

A

The high gain current sense resistor is attached from this pin to ground.

23

VCM_RS2

A

The low gain current sense resistor is connected from this pin to

VCM_RS1

13

VCM+

O

One end of the load is attached to this pin (Positive).

15

VCM-

O

The other end of the load is attached to this pin (Negative).

20

OV_VOLT

O

A voltage which is proportional to the voltage across the load,

19

OV_CUR

O

A voltage which is proportional to the current through the load,

16

OV_SUM–

I

Over-velocity summing op-amp inverting input.

18

OV_SUM_OUT

O

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

Pin Name

Pin Type

Description

11,55,

63

V_RECIR

P

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.

2

LOAD_SOL

O

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.

1

UNLOAD_SOL

O

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.

4

PD_SEQ_CAP

A

When power is removed, the charge stored on this capacitor keeps

selected blocks alive long enough to effect an orderly power down.

52

BRK_DLY

A

An external parallel RC network from this point to ground delays

activation of the dynamic brake after power is removed.

L6245

5/15