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PDF MICRF229 Data sheet ( Hoja de datos )
| Número de pieza | MICRF229 | |
| Descripción | 400MHz to 450MHz ASK/OOK Receiver | |
| Fabricantes | Micrel Semiconductor | |
| Logotipo |  |
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MICRF229
400MHz to 450MHz ASK/OOK Receiver
with Auto-Poll and RSSI
General Description
The MICRF229 is a 400MHz to 450MHz super-
heterodyne, image-reject, RF receiver with automatic gain
control, ASK/OOK demodulator, and analog RSSI output.
It only requires a crystal and a minimum number of
external components to implement. The MICRF229 is ideal
for low-cost, low-power, RKE, TPMS, and remote
actuation applications.
The MICRF229 achieves 112dBm sensitivity at a bit rate
of 1kbps with 1% BER. Eight demodulator filter bandwidths
are selectable in binary steps from 1625Hz to 34kHz at
433.92MHz, allowing the device to support bit rates up to
20kbps. The device operates from a supply voltage of 3.5V
to 5.5V, and typically consumes 6.0mA at 433.92MHz. The
MICRF229 has a shutdown mode and sleep mode that
reduce current to 0.5μA and 15μA respectively.
Datasheets and support documentation are available on
Micrel’s web site at: www.micrel.com.
Features
112dBm sensitivity at 1kbps with 1% BER
Auto-polling mode with bit checking
Supports bit rates up to 20kbps at 433.92MHz
25dB image-reject mixer
No IF filter required
60dB analog RSSI output range
3.5V to 5.5V supply voltage range
6.0mA supply current at 434MHz
15μA supply current in sleep mode
0.5μA supply current in shutdown mode
16-pin 4.9mm × 6.0mm QSOP package
40C to +105C temperature range
2kV HBM ESD rating
Applications
Automotive remote keyless entry (RKE)
Long-range RF ID
Remote fan/light control
Garage door/gate openers
Remote metering
Low data rate unidirectional wireless data links
Typical Application
MICRF229 433.92MHz Typical Application Circuit
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
April 15, 2015
Revision 1.0
1 page  
Micrel, Inc.
MICRF229
Electrical Characteristics (Continued)
VDD = 5.0V, VEN = 5V, SQ = Open, CAGC = 4.7µF, CCTH = 0.1µF, unless otherwise noted. Bold values indicate –40°C ≤ TA ≤ +105°C.
Symbol Parameter
Condition
Min.
Typ.
Max. Units
Reference Oscillator
fRF Reference Oscillator Frequency
Reference Buffer Input Impedance
Reference Oscillator Bias Voltage
Reference Oscillator Input Range
Reference Oscillator Source
Current
Demodulator
CTH Source Impedance(5)
CTH Leakage Current In CTH
Hold Mode
Digital / Control Functions
fRF = 433.92MHz
RO1 when driven externally
RO2
External input, AC couple to RO1
VRO1 = 0V
fREF = 13.52313MHz
TA = +25ºC
TA = +105ºC
13.52313
MHz
1.6 kΩ
1.15 V
0.2 1.5 VP-P
300 µA
120 KΩ
1
10
nA
DO Pin Output Current
Output Rise Time
Output Fall Time
As output source at 0.8VDD
As output sink at 0.2VDD
15pF load on DO pin, transition time
between 0.1VDD and 0.9VDD
300
680
µA
600
ns
200
RSSI(6)
Input High Voltage
Input Low Voltage
Output Voltage High
Output Voltage Low
EN
EN
DO
DO
0.8VDD
0.8VDD
0.2VDD
0.2VDD
V
V
V
V
VRSSI
RSSI DC Output Voltage Range
−110dBm RF input level
−50dBm RF input level
0.5
V
2.0
RSSI Output Current
RSSI Output Impedance
RSSI Response Time
RF Leakage
5kΩ load to GND, −50dBm RF input
level
D[4:3] = 00, RF input power-stepped
from no input to −50dBm
400 µA
240 Ω
10 ms
LO Leakage for 433.92MHz
432.68064MHz (fXAL = 13.52127MHz)
−98 dBm
Notes:
5. CTH source impedance is inversely proportional to the reference frequency. In production test, the typical source impedance value is verified with
12MHz reference frequency.
6. RSSI exhibit variation through manufacturing process, it is recommended that the reading is calibrated by software in system MCU when it is being
used.
April 15, 2015 5 Revision 1.0
5 Page 
Micrel, Inc.
There are eight selectable low-pass filter BW settings:
1625Hz, 3250Hz, 6500Hz, 11000Hz, 13000Hz, 19000Hz,
34000Hz and 46000Hz for 433.92MHz operation. The
low-pass filter BW is directly proportional to the crystal
reference frequency, and hence RF Operating
Frequency. Filter BW values can be easily calculated by
direct scaling. Equation 5 illustrates filter Demod BW
calculation:
×BWOperating Freq = BW@433.92MHz
Operating Freq (MHz)
433.92
Eq. 5
It is very important to select a suitable low-pass filter BW
setting for the required data rate to minimize bit error
rate. Use the sensitivity curves that show BER vs. bit
rates for different D[16:4:3] settings as a guide.
This low-pass filter −3dB corner frequency bandwidth can
be configured by setting the registers as in Table 1 for
433.92MHz.
Table 1. Low-Pass Filter Bandwidth Selection @ 434MHz RF
Input
D[16]
D[4]
D[3]
Low-Pass
Maximum
Filter BW Encoded Bit Rate
0 0 0 1625Hz 2.5KBps
0 0 1 3250Hz
5KBps
0 1 0 6500Hz 10KBps
0 1 1 13000Hz 20KBps
1 0 0 11000Hz
1 0 1 19000Hz Do Not Use
1 1 0 34000Hz
1 1 1 46000Hz
Bit rate refers to the encoded bit rate. Encoded bit rate is
1/(shortest pulse duration) that appears at DO, as
illustrated in Figure 2.
Figure 2. Transmitted Bit Rate through the Air
MICRF229
Alternatively the default registers setting for D[16:4:3] is
011 at power up, without programming the setting of
these bits, the demodulation bandwidth can be selected
externally by SEL1 pin.
Table 2. Demod Bandwidth − SEL1 External Input
SEL1
Bandwidth at 434MHz
0 3250Hz – D3,D4 must be 11
1 13000Hz – default internal pull up
Slicer and CTH
The signal prior to the slicer, labeled “Audio Signal” in the
Functional Diagram, is still baseband analog signal. The
data slicer converts the analog signal into ones and zeros
based on 50% of the slicing threshold voltage built up in
the CTH capacitor. After the slicer, the signal is
demodulated OOK digital data. When there is only
thermal noise at ANT pin, the voltage level on CTH pin is
about 650mV. This voltage starts to drop when there is
RF signal present. When the RF signal level is greater
than −100dBm, the voltage is about 400mV.
The value of the capacitor from CTH pin to GND is not
critical to the sensitivity of MICRF229, although it should
be large enough to provide a stable slicing level for the
comparator. The value used in the evaluation board of
0.1μF is good for all bit rates from 500bps to 40kbps.
The data slice level can be set by programming D[6:5]
bits, which also has the effect on the sensitivity of the
receiver as indicated in the sensitivity graphs.
Table 3. Slice Level − Serial Register Control
D6 D5
Mode
00
Slice level 60%
01
Slice level 30%
10
Slice level 40%
11
Slice level 50% - default
CTH Hold Mode
If the internal demodulated signal (DO in the Functional
Diagram) is at logic LOW for more than about 4msec, the
chip automatically enters CTH hold mode, which holds
the voltage on CTH pin constant even without RF input
signal. This is useful in a transmission gap, or “dead
time”, used in many encoding schemes. When the signal
reappears, CTH voltage does not need to re-settle,
improving the time to output with no pulse width
distortion, or time to good data (TTGD).
April 15, 2015 11 Revision 1.0
11 Page | ||
| Páginas | Total 23 Páginas | |
| PDF Descargar | [ Datasheet MICRF229.PDF ] | |
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