MC33690DWE Freescale Semiconductor, MC33690DWE Datasheet - Page 6

• Manufacturer Part Number: MC33690DWE
• Description: IC STAND ALONE TAG READER 20SOIC
• Manufacturer: Freescale Semiconductor

Specifications of MC33690DWE

• Rf Type: Read / Write
• Frequency: 125kHz
• Features: Wide Supply Voltage Range
• Package / Case: 20-SOIC (0.300", 7.50mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Read Function
2
When answering to the base station, a transponder generates an absorption modulation of the magnetic field. It results in an
amplitude/phase modulation of the current across the antenna. This information is picked up at the antenna tap point between
the coil and the capacitor. An external resistive ladder down scales this voltage to a level compatible with the demodulator input
voltage range (see
The demodulator (see
The sampling time is automatically set to take into account a phase shift due to the tolerances of the antenna components (L and
C) and of the oscillator. The allowed phase shift measured at the input RD ranges from −45° to +45°. Assuming that the phase
6
•
•
•
•
L
C
R
A
an input stage (emitter follower)
a sample and hold circuit
a voltage follower
a low offset voltage comparator
A
A
Read Function
R
R
1
2
Section 15, “Tag
TD2
TD1
RD
Figure
-
+
VDD
2) consists of:
Buffer
125 kHz
+0°, -11.25°, -22.5°, -33.75°, -45°, -56.25°, -67.5°, -78.75°
Reader”).
11.25°, 22.5°, 33.75°, 45°, 56.25°, 67.5°, 78.75°, 90°
MC33690 Standalone Tag Reader Circuit, Rev. 5
S/H
Figure 2. Tag Reader Block Diagram
125 kHz
500ns
1/32 counter
Self synchronous
sample and hold
+
-
Buffer
AGND
4 MHz
1/2
100KW
C
EXT
8 MHz
Comparator
CEXT
+
VDD
-
Setup and Preload
10nF
500mA
D
C
Q
Freescale Semiconductor
Clock 8 MHz
AM Data
Shutdown
Interface
Data out
LVR