A3904
Low Voltage Voice Coil Motor Driver
Features and Benefits
▪
Fixed
logic thresholds
▪
8-bit D-to-A converter
▪
500
μA
resolution
▪
Low voltage I
2
C serial interface
▪
Low current-draw sleep mode
▪
2.4 to 5.5 V operation
▪
2 mm × 1.5 mm, 0.38 mm nominal overall height DFN
▪
1.1 mm × 0.7 mm, 0.5 mm maximum overall height WLCSP
▪
1.1 mm × 0.7 mm, 0.33 mm nominal overall height bare die
I
2
C
Description
The A3904 is a voice coil motor (VCM) driver, with an
I
2
C-compatible serial interface. Designed for camera autofocus
and zoom applications, this high accuracy digital IC is provided
in small packages ideal for portable devices. Its operating
voltage range is 2.4 to 5.5 V, and its maximum output current
is 127 mA.
Output current is programmed via the I
2
C interface, in 500 uA
increments, with clock rates up to 400 kHz. I
2
C inputs set the
internal D-to-A converter output voltage that is the reference
for linear current control via a MOSFET output sink transistor.
To conserve battery power, a logic low signal on the SLEEPZ
input disables the output MOSFET and reduces the supply
current to <0.5
μA.
A3904 internal protection features include thermal shutdown
and undervoltage lockout. Logic input levels are independent
of the supply voltage. The operating temperature range is
–40°C to 85°C.
The A3904 is available at three packaging levels: bare die on
wafer (suffix CW); bumped wafer level chip scale package
(WLCSP) (suffix CG); and complete thin profile (0.38 mm
nominal overall height) DFN package, with NiAuPd leadframe
plating and an exposed tab for enhanced thermal dissipation
(suffix EW).
Packages:
1.5 mm × 2 mm DFN
(EW package)
1.1 mm × 0.7 mm WLCSP
(CG package)
Not to scale
Bare die
(CW package)
Functional Block Diagram
1.8 V
2.4 to 5.5 V
VDD
IOUT
1.8 kΩ
1.8 kΩ
I
2
C
Master
SDA
SCL
Bandgap
Ref
8 Bit DAC
I
2
C Serial
Interface
2.4
Ω
GND
I
2
C
Slave
SLEEPZ
PAD
EW only
3904-DS, Rev. 2