OM5193H Datasheet, PDF (27/56 Pages) NXP Semiconductors – Disk drive spindle and VCM with servo controller

Philips Semiconductors
Disk drive spindle and VCM with
servo controller
Product specification
OM5193H
handbook, full pagewidth
COMA
0
1
COMB
0
0
COMC
0
0
MOTA
L
L
MOTB
MOTC
H
F
F
H
ACROSS
BCROSS
CCROSS
ZCROSS
1
1
1
1
0
1
F
H
L
L
H
F
0
0
1
0
1
1
H
F
F
H
L
L
MGM981
L = LOW.
H = HIGH.
F = Floating.
Fig.12 Input commutations to output drivers.
8.11 VCM driver
The VCM driver is a linear, class AB amplifier with both low-side and high-side drivers configured as an H-bridge.
The zero-current reference voltage for the VCM loop is internally set at 2.5 V. The sense resistor R_VCMSENSE enables the
VCM current (I_VCMRUN) to be measured through the sense amplifier. The gain G_v of the sense amplifier is typically 4.
The output voltage (V_sout) on pin ADC[2]/SOUT is given by the following equation:
V_sout = G_v × R_VCMSENSE × I_VCMRUN + V_ref2V5
= G_v × (V_VCMSENSEH – V_VCMSENSEL) + V_ref2V5
(17)
Figure 13 presents the VCM sense amplifier.
1998 Nov 02
27