motor-driver

Philips Semiconductors
12 V Voice Coil Motor (VCM) driver and
spindle motor drive combination chip
Preliminary specification
TDA5147CH
EQUATIONS
Gain from V FLTINP to V FLTOUT :
–
-------------------------------------------- = 2
–
V FLTOUT
V FLTINP
V refout
V refout
Gain from V FLTOUT to V ISENS1 (under closed loop V CMINP =V refout ):
V FLTOUT
– V refout
-------------------------------------------- =
R1
V ISENS1
– V refout
------------------------------------------ or V FLTOUT
– V refout
-------------------------------------------- =
R2
–
V SENS1
Gain of V ISENS1 relative to ∆ V s (voltage across R s ):
HAVE V1 – V refout
---------------------------- =
4R
V ISENH
------------------
R
V1 – V SENS1
-------------------------------- =
4R
V ISENL
-----------------
R
V refout
R1
------
R2
(1)
(2)
(3)
SUB 1 – V refout
------------------------ =
4R
V ISENL
– V ISENH
------------------------------------------- =
R
∆V s
--------- or V SENS1
– V refout
----------------------------------------- = 4
R ∆V s
(4)
Transconductance equation:
G m
=
I coil
--------------------------------------------
V FLTINP
– V refout
∆V s 1
= --------- × ------------------------------------------
–
R s
V FLTINP
V refout
(5)
From equation (1):
G m
=
∆V s
---------
R s
2
--------------------------------------------
–
V FLTOUT
V refout
From equation (2):
G m
=
∆V s
--------- × 2 × R2 ------ ( V
R1 SENS1
– V refout
)
R s
1 1
From equation (3) and (4): G m
= ------ × -- × 2 × R2 ------ =
4 R1
R s
1
--
2
1
× ------
R s
R2
× -------
R1
1997 Jul 09 24