iC-PD3948
preliminar y
Rev B4, Page 2/9
5-CHAN. PHASED ARRAY SINE ENCODER 39-2048
DESCRIPTION
iC-PD3948 is an optical sensor IC with integrated
photodiodes whose signal currents are converted
into output voltages by low-noise transimpedance
amplifiers.
Due to a high transimpedance gain of typically
4 MΩ, output signal voltages of several hundred Mil-
livolts are obtained at illumination levels of just 1 to
3 mW/cm
2
. In most cases complicated noise sup-
pression measures are thus rendered unnecessary.
As the pin names would suggest, iC-PD3948 is typ-
ically applied as a sine encoder for motor feedback
systems. To this end, iC-PD3948 provides sine and
cosine signals with both a high resolution of 2048
PPR (plus an additional index signal) and a low res-
olution of 1 PPR (at C/D).
All code disc signal tracks are evaluated differentially;
the high resolution sine signals are read by photo-
diodes in a phased array. The layout of the signal
amplifiers is such that there is good paired channel
matching, reducing the time and effort required for
calibration to an absolute minimum.
The spectral sensitivity ranges from visible to near
infrared light, with the maximum sensitivity close to
a wavelength of 680 nm. An output voltage of 1 V
is typical in low light conditions, for instance when iC-
PD is illuminated at only 2 mW/cm
2
by a 740 nm LED.
A relatively low LED current is enough to operate the
sensor, proving beneficial to the life expectancy of the
LED at high operating temperatures.
PACKAGES AND CHIP LAYOUT INFORMATION
PAD LAYOUT (2.88 mm x 3.37 mm)
PAD FUNCTIONS
No. Name Function
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
VCC
VREF
PSIN
NSIN
PCOS
NCOS
Z
NZ
ND
PD
NC
PC
VRDC
VRSC
GND
+4.5...5.5 V Supply Voltage
Reference Voltage Output
Sine Track +
Sine Track -
Cosine Track +
Cosine Track -
Z Index Signal
Z Index Track -
D Track -
D Track +
C Track -
C Track +
D/C Track Reference
S/C Track Reference
Ground
Notes: All outputs are analog voltage
outputs.
ICHAUS [ IC-HAUS GMBH ]
