Freescale MC33493ADTB Pll tuned uhf transmitter for data transfer application Datasheet

Freescale Semiconductor
Data Sheet: Product Preview
Document Number: MC33493A
Rev. 2, 07/2007
MC33493A
PLL Tuned UHF Transmitter
for Data Transfer
Applications
•
•
•
•
•
•
•
•
•
•
•
Selectable frequency bands:
315—434 MHz and 868—928 MHz
On Off Keying (OOK) and Frequency Shift Keying
(FSK) modulation
Adjustable output power range
Fully integrated voltage control regulator (VCO)
Supply voltage range: 1.9—3.6 V
Very low standby current: 0.1 nA @ TA= 25 °C
Low-supply voltage shutdown
Data clock output for microcontroller
Extended temperature range: –20 to 85 °C
Low external component count
Typical application compliant with European
Telecommunications Standards Institute (ETSI)
standard
PIN CONNECTIONS
DATACLK
1
14
MODE
DATA
2
13
ENABLE
BAND
3
12
VCC
GND
4
11
GNDRF
XTAL1
5
10
RFOUT
XTAL0
6
9
VCC
REXT
7
8
CFSK
Ordering Information
Device
MC33493ADTB
Ambient
Temperature
Range
Package
–20°C to 85°C TSSOP14
MC3493ADTBE –20°C to 85°C TSSOP14
(ROHS)
This document contains information on a product under development. Freescale reserves the
right to change or discontinue this product without notice.
© Freescale Semiconductor, Inc., 2007. All rights reserved.
Table of Contents
1
2
3
4
5
6
7
8
9
10
11
12
Transmitter Functional Description . . . . . . . . . . . . . . . . . . . . . .4
Phase Locked Loop and Local Oscillator . . . . . . . . . . . . . . . . .4
RF Output Stage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Microcontroller Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
State Machine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Power Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Data Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Radio Frequency (RF) Output Spectrum . . . . . . . . . . . . . . . .11
Output Power Measurement . . . . . . . . . . . . . . . . . . . . . . . . . .14
Complete Application Schematic and
PCB for OOK Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
13 Complete Application Schematic and
PCB for FSK Modulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
14 Recommendations for FSK Modulation . . . . . . . . . . . . . . . . .19
15 Case Outline Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
List of Figures
Figure 1. Simplified Block Diagram . . . . . . . . . . . . . . . . . . . . . . . 3
Figure 2. Crystal Pulling Configurations. . . . . . . . . . . . . . . . . . . . 5
Figure 3. State machine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 4. Signals Waveform and Timing Definition . . . . . . . . . . . 7
Figure 5. RF Spectrum at 434 MHz Frequency Band
Displayed with a 5 MHz Span . . . . . . . . . . . . . . . . . . . 11
Figure 6. RF Spectrum at 434 MHz Frequency Band
Displayed with a 50 MHz Span . . . . . . . . . . . . . . . . . . 11
Figure 7. RF Spectrum at 434 MHz Frequency Band
Displayed with a 1.5 GHz Span . . . . . . . . . . . . . . . . . 12
Figure 8. RF Spectrum at 434 MHz Band
for a 70 kHz FSK Deviation at 4.8 kbit/s . . . . . . . . . . . 12
Figure 9. Output Power Measurement Configurations . . . . . . . .
Figure 10.Output Model and Matching Network
for 434 MHz Band . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 11.Output Power at 434 MHz Band vs Rext Value . . . . .
Figure 12.Application Schematic for OOK Modulation,
434 MHz Frequency Band . . . . . . . . . . . . . . . . . . . . . .
Figure 13.Two-Button Keyfob Board Layout . . . . . . . . . . . . . . . .
Figure 14.Application Schematic for FSK Modulation,
Serial Configuration, 434 MHz Frequency Band . . . . .
Figure 15.Application PCB Layout for FSK Modulation,
Serial Configuration, 434 MHz Frequency Band . . . . .
Figure 16.Crystal Load Capacitance Contributors Schematic . .
Figure 17.Case Outline Dimensions . . . . . . . . . . . . . . . . . . . . .
13
13
14
15
16
17
18
19
20
List of Tables
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Table 7.
Table 8.
Table 9.
Pin Function Description . . . . . . . . . . . . . . . . . . . . . . . . 3
Absolute Maximum Ratings. . . . . . . . . . . . . . . . . . . . . . 3
Band Selection and Associated Divider Ratios . . . . . . . 4
DATACLK Frequency vs Crystal Oscillator Frequency. . 5
Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . 8
External Components Description for OOK. . . . . . . . . 15
Typical Crystal Characteristics (SMD Package) . . . . . 16
External Components Description for FSK . . . . . . . . . 17
Crystal Pulling Capacitor Values vs
Carrier Frequency Total Deviation -1- . . . . . . . . . . . . . 18
Table 10.Crystal Pulling Capacitor Values vs
Carrier Frequency Total Deviation -2- . . . . . . . . . . . . . 18
Table 11.Pads and Tracks Parasitic Values . . . . . . . . . . . . . . . . 19
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
2
Freescale Semiconductor
Figure 1. Simplified Block Diagram
Table 1. Pin Function Description
Pin
Name
Description
1
2
3
4
5
6
7
8
9
10
11
12
13
14
DATACLK
DATA
BAND
GND
XTAL1
XTAL0
REXT
CFSK
VCC
RFOUT
GNDRF
VCC
ENABLE
MODE
Clock output to the microcontroller
Data input
Frequency band selection
Ground
Reference oscillator input
Reference oscillator output
Power amplifier output current setting input
FSK switch output
Power supply
Power amplifier output
Power amplifier ground
Power supply
Enable input
Modulation type selection input
Table 2. Absolute Maximum Ratings
Parameter
Supply voltage
Symbol
Value
Unit
VCC
VGND – 0.3 to 3.7
V
VGND – 0.3
to VCC + 0.3
V
±2000
V
±150
V
Voltage allowed on each pin
ESD HBM voltage capability on each pin 1(note 1)
2
ESD MM voltage capability on each pin (note 2)
Storage temperature
Ts
–65 to +150
°C
Junction temperature
Tj
+150
°C
1
2
Human Body model, AEC-Q100-002 Rev. C.
Machine Model, AEC-Q100-003 Rev. E.
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
Freescale Semiconductor
3
Transmitter Functional Description
1
Transmitter Functional Description
MC33493A is a PLL-tuned low-power UHF transmitter. The different modes of operation are controlled by the microcontroller
through several digital input pins. The power supply voltage ranges from 1.9 V to 3.6 V, allowing operation with a single lithium
cell.
2
Phase Locked Loop and Local Oscillator
The VCO is a completely integrated relaxation oscillator. The phase frequency detector (PFD) and the loop filter are fully
integrated. The exact output frequency is equal to: fRFOUT = fXTAL × [PLL divider ratio]. The frequency band of operation is
selected through the BAND pin.
Table 3 shows details for each frequency band selection.
Table 3. Band Selection and Associated Divider Ratios
BAND Input Level
High
Low
Frequency Band
(MHz)
315
434
868
PLL Divider Ratio
Crystal Oscillator
Frequency (MHz)
32
64
9.84
13.56
An out-of-lock function is performed by monitoring the PFD output voltage. When it exceeds defined limits, the RF output stage
is disabled.
3
Radio Frequency (RF) Output Stage
The radio frequentcy (RF) output stage source is a single-ended square-wave switched current. Harmonics are present in the
output current drive. Their radiated absolute level depends on the antenna characteristics and output power. Typical application
demonstrates compliance to ETSI standard.
A resistor, Rext, connected to the REXT pin controls the output power allowing a trade-off between radiated power and current
consumption.
The output voltage is internally clamped to Vcc ± 2 Vbe (typ. Vcc ± 1.5 V @ TA=25 °C).
4
Modulation
To select the On Off Keying (OOK) modulation, a low-logic level must be applied on the MODE pin. This modulation is
performed by switching the RF output stage on or off. The logic level applied on the DATA pin controls the output stage state:
DATA = 0 → output stage off,
DATA = 1 → output stage on.
Applying a high-logic level on the MODE pin selects Frequency Shift Keying (FSK) modulation. This modulation is achieved
by crystal pulling. An internal switch connected to the CFSK pin enables switching the external crystal load capacitors. Figure 2
shows the possible configurations: serial and parallel.
The logic level applied on pin DATA controls the state of this internal switch:
DATA=0 → switch off,
DATA=1 → switch on.
DATA input is internally re-synchronized by the crystal reference signal. The corresponding jitter on the data duty cycle cannot
exceed ±1 reference period (±75 ns for a 13.56 MHz crystal).
This crystal pulling solution implies that the RF output frequency deviation equals the crystal frequency deviation multiplied
by the PLL Divider ratio (see Table 3).
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
4
Freescale Semiconductor
Microcontroller Interface
Figure 2. Crystal Pulling Configurations
5
Microcontroller Interface
Four digital input pins (ENABLE, DATA, BAND, and MODE) enable the circuit to be controlled by a microcontroller. The
band frequency and the modulation type should be configured before enabling the circuit.
One digital output pin, DATACLK, provides the microcontroller with a reference frequency for data clocking. This frequency
is equal to the crystal oscillator frequency divided by 64 (see Table 4).
Table 4. DATACLK Frequency vs Crystal Oscillator Frequency
Crystal Oscillator Frequency (MHz)
DATACLK Frequency (kHz)
9.84
13.56
154
212
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
Freescale Semiconductor
5
State Machine
6
State Machine
Figure 3 details the state machine.
Power ON
AND ENABLE=0
State 1
Standby mode
ENABLE=0
ENABLE=1
State 2
PLL out of lock-in range
No RF output
PLL in
lock-in range
PLL out of
lock-in range
ENABLE=0
State 4
Shutdown mode
Vbattery < Vshutdown
State 3
Transmission mode
Figure 3. State machine
State 1: The circuit is in standby mode and draws only a leakage current from the power supply.
State 2: In this state, the PLL is out of the lock-in range; therefore, the RF output stage is switched off, preventing RF
transmission. Data clock is available on the DATACLK pin. Each time the device is enabled, the state machine passes through
this state.
State 3: In this state, the PLL is within the lock-in range. If t < tPLL_lock_in, the PLL may be in acquisition mode. If t≥tPLL_lock_in,
then the PLL is locked. Data entered on the DATA pin are output on the RFOUT pin according to the modulation selected by
the level applied on the MODE pin.
State 4: When the supply voltage falls below the shutdown voltage threshold (VSDWN,) the entire circuit switches off. After this
shutdown, applying a low level on the ENABLE pin unlatches the circuit.
Figure 4 shows the waveforms of the main signals for a typical application cycle.
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
6
Freescale Semiconductor
Power Management
ENABLE
DATACLK
tDATACLK_settling > tPLL_lock_in
c
tPLL_lock_in
DATA
MODE=0 (OOK)
fcarrier
RFOUT
fcarrier
MODE=1 (FSK)
fhigh
State 1
flow
State 2
fhigh
flow
State 3
fhigh
State 1
c : PLL locked
Figure 4. Signals Waveform and Timing Definition
7
Power Management
When the battery voltage falls below the shutdown voltage threshold (VSDWN) the entire circuit switches off. After this
shutdown, the circuit is latched until a low level is applied on pin ENABLE (see State 4 of the state machine).
8
Data Clock
At start-up, data clock timing is valid after the data clock settling time. Because the clock is switched off asynchronously, the
last period duration cannot be guaranteed.
9
Electrical Characteristics
Unless otherwise specified, voltage range Vcc=[Vshutdown;3.6 V], temperature range TA=[–20 °C;+ 85 °C], Rext=12 kΩ ± 5%,
RF output frequency fcarrier = 433.92 MHz, reference frequency freference = 13.560 MHz, output load RL = 50 Ω ±1%
(Figure 9). Values refer to the circuit shown in the recommended application schematics: Figure 12 shows OOK modulation
and Figure 14 shows FSK modulation. Typical values reflect average measurement at VCC =3 V, TA = 25 °C.
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
Freescale Semiconductor
7
Electrical Characteristics
Table 5. Electrical Characteristics
Limits
Parameter
Test Conditions, Comments
Unit
Min.
Typ.
Max.
TA ≤ 25 °C
—
0.1
5
nA
TA = 60 °C
—
7
30
nA
1.3
TA = 85 °C
—
40
150
nA
315 and 434 bands,
OOK and FSK modulation,
continuous wave, TA = 25 °C
—
11.6
13.5
mA
1.7
1.5
315 and 434 bands,
DATA=0, –20 °C ≤ TA ≤ 85 °C
—
4.4
5.5
mA
868 MHz band,
DATA=0, –20 °C ≤ TA ≤ 85 °C
—
4.6
5.7
mA
315 and 434 bands,
OOK and FSK modulation,
continuous wave, –20 °C ≤ TA ≤85 °C
—
11.6
14.4
mA
1.8
868 MHz band,
OOK and FSK modulation,
continuous wave, –20 °C ≤T A ≤ 85 °C
—
11.8
14.6
mA
1.9
—
3
3.6
V
TA = –20 °C
—
1.99
2.06
V
TA = 25 °C
—
1.86
1.95
V
1.14
TA = 60 °C
—
1.76
1.84
V
1.15
TA = 85 °C
—
1.68
1.78
V
12
—
21
kΩ
1
General Parameters
1.1
1.2
1.6
1.10
Supply current in
standby mode
Supply current in
transmission mode
Supply voltage
1.12
1.13
Shutdown voltage threshold
2
2.1
RF Parameters
Rext value
2.2
315 and 434 MHz bands,
with 50 Ω matching network
—
5
—
dBm
2.3
868 MHz band,
with 50 Ω matching network
—
1
—
dBm
2.4
315 and 434 MHz bands,
–20 °C ≤ TA ≤ 85 °C
–2.5
0
2.5
dBm
2.8
868 MHz band,
–20 °C ≤TA ≤ 85 °C
–6
–3
0
dBm
315 and 434 MHz bands,
with 50 Ω matching network
—
–0.35
–0.25
—
dB/kΩ
mA/kΩ
315 and 434 MHz bands,
with 50 Ω matching network
—
–34
—
dBc
868 MHz band,
with 50 Ω matching network
—
–49
—
dBc
2.15
315 and 434 MHz bands
—
–23
–17
dBc
2.16
868 MHz band
—
–38
–27
dBc
Output power
2.12
Current and output power
variation vs. Rext value
2.13
2.14
Harmonic 2 level
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
8
Freescale Semiconductor
Electrical Characteristics
Table 5. Electrical Characteristics (continued)
Limits
Parameter
Test Conditions, Comments
Unit
Min.
Typ.
Max.
315 and 434 MHz bands,
with 50 Ω matching network
—
–32
—
dBc
2.18
868 MHz band,
with 50 Ω matching network
—
–57
—
dBc
2.19
315 and 434 MHz bands
—
–21
–15
dBc
2.20
868 MHz band
—
–48
–39
dBc
Spurious level
@ fcarrier ± f DATACLK
315 and 434 MHz bands
—
–36
–24
dBc
868 MHz band
—
–29
–17
dBc
Spurious level
@ fcarrier ± f reference
315 MHz band
—
–37
–30
dBc
434 MHz band
—
–44
–34
dBc
868 MHz band
—
–37
–27
dBc
315 MHz band
—
–62
–53
dBc
434 MHz band
—
–80
–60
dBc
868 MHz band
—
–45
–39
dBc
315 and 434 MHz bands,
±175 kHz from f carrier
—
–75
–68
dBc/Hz
868 MHz band,
±175 kHz from f carrier
—
–73
–66
dBc/Hz
fcarrier within 30 kHz from the final value,
crystal series resistor = 150 Ω
—
400
1600
µs
—
1
—
pF
—
20
200
Ω
20
50
75
90
—
dBc
2.17
Harmonic 3 level
2.21
2.22
2.23
2.24
2.25
2.41
2.26
Spurious level
@ fcarrier/2
2.27
2.30
Phase noise
2.31
2.32
PLL lock-in time,
tPLL_lock_in
2.33
XTAL1 input capacitance
2.34
Crystal resistance
2.44
OOK modulation
FSK modulation
2.35
OOK modulation depth
2.36
FSK modulation
carrier frequency
total deviation
315 and 434 MHz bands, see note
—
—
100
kHz
868 MHz band, see note
—
—
200
kHz
CFSK output resistance
MODE = 0, DATA = x
MODE = 1, DATA = 0
50
70
—
kΩ
MODE = 1, DATA = 1
—
90
300
Ω
—
1
—
pF
Manchester coding
—
—
10
kbit/s
MODE = 0, see note
3.5
5.25
7.5
µs
MODE = 1, see note
–200
—
200
ns
2.37
2.38
2.39
2.43
CFSK output capacitance
2.40
Data rate
2.41 Data to RF delay difference between
2.42
falling and rising edges,
tdelay_difference
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
Freescale Semiconductor
9
RF Output Spectrum
Table 5. Electrical Characteristics (continued)
Limits
Parameter
Test Conditions, Comments
Unit
Min.
Typ.
Max.
Note: This parameter depends on crystal characteristics, load capacitor values (see Table 4) and PCB track capacitance.
Note: Delay difference definition
Input data
From 50% of data edge to corresponding
demodulated signal envelope edge:
tdelay_difference = tdelay_fall – tdelay_rise
Demodulated data
tdelay_rise
3
3.1
3.2
tdelay_fall
Microcontroller Interfaces
Input low voltage
Input high voltage
Pins: BAND, MODE, ENABLE, and DATA
0
—
0.3 x
VCC
V
0.7 x
VCC
—
VCC
V
—
—
120
mV
—
—
100
nA
3.3
Input hysteresis voltage
3.4
Input current
3.5
ENABLE pulldown resistor
—
180
—
kΩ
DATACLK output low voltage
0
—
0.25 x
VCC
V
3.6
Pins: BAND, MODE, DATA = 1
DATACLK output high voltage
Cload = 2 pF
0.75 x
VCC
—
VCC
V
3.8
DATACLK rising time
—
250
500
ns
3.9
DATACLK falling time
Cload = 2 pF, measured from 20% to 80% of the
voltage swing
—
150
400
ns
3.10
DATACLK settling time,
tDATACLK_settling
—
800
2000
µs
3.7
10
45% < duty cycle fDATACLK < 55%
RF Output Spectrum
The following figures represent spectrums of the transmitter carrier, measured in conduction mode. Three different spans have
been used. The 5 MHz span spectrum (Figure 5) shows phase noise response close to the RF carrier and the noise suppression
within the PLL-loop bandwidth. The 50 MHz span spectrum (Figure 6) shows phase noise and reference spurious. Finally, the
1.5 GHz span spectrum (Figure 7) shows the second and third harmonics of carrier. All spectrums are measured in OOK
modulation at DATA=1.
Figure 8 shows the spectrum in case of FSK modulation with 45 kHz deviation at 4 kbit/s data rate.
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
10
Freescale Semiconductor
RF Output Spectrum
Resolution
bandwidth:
100kHz
Resolution
bandwidth:
30kHz
Figure 5. RF Spectrum at 434 MHz Frequency Band Displayed with a 5 MHz Span
Figure 6. RF Spectrum at 434 MHz Frequency Band Displayed with a 50 MHz Span
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
Freescale Semiconductor
11
RF Output Spectrum
Figure 7. RF Spectrum at 434 MHz Frequency Band Displayed with a 1.5 GHz Span
Figure 8. RF Spectrum at 434 MHz Band for a 70 kHz FSK Deviation at 4.8 kbit/s
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
12
Freescale Semiconductor
Output Power Measurement
11
Output Power Measurement
The RF output levels given in Section 9, “Electrical Characteristics,” are measured with a 50 Ω load directly connected to the
RFOUT pin, as shown below in Figure 9. This wideband coupling method gives results independent of the application.
VCC
Impeder: TDK MMZ1608Y102CTA00
RFOUT
RF output
100 pF
RL= 50 W
Figure 9. Output Power Measurement Configurations
The configuration shown in Figure 10(a) provides better efficiency in terms of output power and harmonics rejection. The
schematic on Figure 10(b) gives the equivalent circuit of the RFOUT pin and the DC bias impeder as well as matching network
components for 434 MHz frequency band.
VCC
Impeder: TDK MMZ1608Y102CTA00
RFOUT
(a)
Matching
Network
RF output
RL=50 Ω
Matching
Network
L1
39 nH
(b)
C0
1.5 pF
R0
250 Ω
RFOUT pin
3 kΩ
C3
50 Ω
330pF
Ri
Impeder
RL
Load
Figure 10. Output Model and Matching Network for 434 MHz Band
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
Freescale Semiconductor
13
Complete Application Schematic and PCB for OOK Modulation
Figure 11 shows the output power versus the Rext resistor value with 50 Ω load and with matching network.
Output power measurement in typical conditions (434MHz - Vcc=3V - 25°C)
REXT SPECIFIED RANGE
8
6
Output power when matched (dBm)
-0.35dB/kΩ
Ω # -0.35mA/kΩ
Ω
4
2
RFOUT
Level (dBm)
0
-2
Output power on 50Ω
Ω load (dBm)
-4
-6
6
9
12
15
Rext (kΩ
Ω)
18
21
24
Figure 11. Output Power at 434 MHz Band vs Rext Value
The 50 Ω matching network used for the 868 MHz band is similar to the 434 MHz, excepting components values: L1 is changed
to 8.2 nH and C3 to 470 pF in Figure 11. The typical gain of this 868 MHz matching network is 4 dB compared to unmatched
configuration.
12
Complete Application Schematic and PCB for OOK
Modulation
Figure 12 shows a complete application schematic using a MC68HC908RK2 microcontroller. OOK modulation is selected,
fcarrier = 433.92 MHz. The C2 to C5 capacitors can be removed if switch debounce is done by software.
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
14
Freescale Semiconductor
Complete Application Schematic and PCB for OOK Modulation
Vbat
SW1
SW1a
SW2a
SW2
Vbat
LED1
1
B1
C2
C3
C4
C5
2.2nF
2.2nF
2.2nF
2.2nF
2
R1
750
Vbat
U1
1
2
3
U2
1
2
3
4
5
6
7
8
9
10
PTA0
20
PTA1/KBD1
PTB0/MCLK
PTA2/KBD2
PTB1
PTA3/KBD3
PTB2/TCH0
PTA4/KBD4
PTB4/TCH1
PTA5/KBD5
PTB5
PTA6/KBD6
PTB3/TCLK
5
19
RST
OSC2
IRQ1
VSS
VDD
MC68HC908RK2
Y1
6
13.56MHz
18
7
17
R2
16
MODE
DATA
ENABLE
BAND
VCC
GND
GNDRF
XTAL1
RFOUT
XTAL0
VCC
REXT
CFSK
C7
22nF
13
12
11
10
C9
2.2pF
9
8
MC33493
C8
12K
100pF
15
PTA7
OSC1
4
C6 8.2pF
DATACLK
14
14
13
12
11
Vbat
C10
100nF
Figure 12. Application Schematic for OOK Modulation, 434 MHz Frequency Band
For 868 MHz band application, the input pin BAND must be wired to ground. See component description on Table 6 and
Table 7.
Table 6. External Components Description for OOK
Component
Function
Value
Unit
Y1
Crystal,
see Table 7
R2
RF output level setting
resistor (Rext)
Crystal load capacitor
Power supply decoupling
capacitors
315 MHz band: 9.84
434 MHz band: 13.56
868 MHz band: 13.56
12
MHz
MHz
MHz
kΩ
8.21
22
100
pF
nF
pF
C6
C7
C8
1
C6 value equals recommended crystal load capacitance reduced by the PCB stray capacitances.
Examples of crystal reference are given below (see characteristics in Table 7) for different application bands:
•
•
at 315 MHz band (freference = 9.84375 MHz, –40 °C < TA < 85 °C): NDK LN-G102-950,
at 434/868 MHz bands (freference = 13.56 MHz, –40 °C < TA < 125 °C): NDK NX8045GB/CSJ S1-40125-8050-12
and NDK NX1255GA.
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
Freescale Semiconductor
15
Complete Application Schematic and PCB for FSK Modulation
)
Table 7. Typical Crystal Characteristics (SMD Package)
NDK NX8045GB/CSJ
NDK NX1255GA
S1-40125-8050-12
(for 434 MHz and 868 MHz)
(for 434 MHz and 868 MHz)
Parameter
NDK LN-G102-950
(for 315 MHz)
Load capacitance
12
12
12
pF
Motional capacitance
3.33
4.4
10.5
fF
Static capacitance
1.05
1.5
2.46
pF
Loss resistance
28
18.5
10
Ω
Unit
Figure 13 shows a two-button keyfob board. Size is 30 × 45 millimeters.
Figure 13. Two-Button Keyfob Board Layout
13
Complete Application Schematic and PCB for FSK
Modulation
Figure 14 shows a complete application schematic using a MC68HC908RK2 microcontroller. FSK modulation is selected,
fcarrier= 433.92 MHz. C1 capacitor can be removed if switch debounce is done by software.
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
16
Freescale Semiconductor
Complete Application Schematic and PCB for FSK Modulation
Figure 14. Application Schematic for FSK Modulation, Serial Configuration, 434 MHz Frequency Band
For 868 MHz band application, the input pin BAND must be wired to ground. See component description in Table 8.
Table 8. External Components Description for FSK
Component
Function
Value
Unit
Y1
Crystal
315 MHz band: 9.84,
See Table 7
MHz
434 MHz band: 13.56,
see Table 7
MHz
868 MHz band: 13.56,
see Table 7
MHz
R1
RF output level setting
resistor (Rext)
12
kΩ
C3
Crystal load capacitor
See Table 9
pF
C4
C2
pF
Power supply decoupling capacitor
C6
22
nF
100
pF
Figure 15 shows the corresponding PCB layout.
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
Freescale Semiconductor
17
Recommendations for FSK Modulation
Figure 15. Application PCB Layout for FSK Modulation, Serial Configuration, 434 MHz Frequency Band
Table 9 gives the measured FSK deviations respective to C3 and C4 capacitor values for three deviations. Crystal reference is
NDK NX8045GB/CSJ S1-40125-8050-12.
Table 9. Crystal Pulling Capacitor Values vs Carrier Frequency Total Deviation -1Carrier frequency
(MHz)
Carrier frequency total
deviation (kHz)
C3 capacitor (pF)
C4 capacitor (pF)
Recommended
R_off value (kΩ)
434
45
4.7
6.8
10
70
2.2
10
—
100
1
15
22
90
4.7
6.8
10
140
2.2
10
—
200
1
15
22
868
Another crystal reference, NDK NX1255GA (see Table 7), is enabled to reach higher deviation as mentioned on Table 10.
These results are due to the higher crystal motional capacitor.
Table 10. Crystal Pulling Capacitor Values vs Carrier Frequency Total Deviation -2-
14
Carrier frequency
(MHz)
Carrier frequency total
deviation (kHz)
C3 capacitor value
(pF)
C4 capacitor value
(pF)
Recommended
R_off value (kΩ)
434
150
1
27
—
868
300
1
27
—
Recommendations for FSK Modulation
FSK deviation is function of total load capacitance presented to the crystal. This load capacitance is constituted by various
contributors:
•
•
•
•
the crystal characteristic, especially its static capacitance
the external load capacitors (C3, C4 as defined in Figure 14 and Table 9)
the device internal capacitance of pins XTAL0, XTAL1, CFSK
the PCB track capacitance
The schematic given in Figure 16 shows a typical FSK application using serial capacitor configuration, where device pads and
PCB track capacitances are mentioned.
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
18
Freescale Semiconductor
Recommendations for FSK Modulation
Device pad capacitance is defined by the package capacitance and by the internal circuitry. Typical capacitance values for these
pads are given in Table 11.
Some realistic assumptions and measurements have been made concerning track parasitic capacitances for a 0.8 mm FR4
double side application PCB. They are given in Table 11 and the corresponding PCB layout is shown in figure Figure 17.
To achieve large deviations, this total load capacitance must be lowered. For a given crystal, the PCB must be carefully laid out
to reduce the capacitance of the tracks wired to XTAL0, XTAL1, and CFSK pins.
Recommendation: a R_off resistor can be added in parallel with the FSK switch to optimize the transient response of
demodulated signal. Table 11 gives the optimized R_off values for two deviations. There is no footprint for R_off resistor on
the layout in Figure 16. When used, this component can be soldered on top of C3.
Figure 16. Crystal Load Capacitance Contributors Schematic
Table 11. Pads and Tracks Parasitic Values
Capacitance
Value
Unit
C_pad_XTAL0
1
pF
C_pad_XTAL1
1
pF
C_pad_CFSK
1
pF
C_track_XTAL0
1.5
pF
C_track_XTAL1
1.5
pF
C_track_CFSK
1.5
pF
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
Freescale Semiconductor
19
Case Outline Dimensions
15
Case Outline Dimensions
14X K REF
NOTES:
1. DIMENSIONING AND TOLERANCING PER
ANSI Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DIMENSION A DOES NOT INCLUDE MOLD
FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH OR GATE BURRS SHALL NOT
EXCEED 0.15 (0.006) PER SIDE.
4. DIMENSION B DOES NOT INCLUDE
INTERLEAD FLASH OR PROTRUSION.
INTERLEAD FLASH OR PROTRUSION SHALL
NOT EXCEED
0.25 (0.010) PER SIDE.
5. DIMENSION K DOES NOT INCLUDE DAMBAR
PROTRUSION. ALLOWABLE DAMBAR
PROTRUSION SHALL BE 0.08 (0.003) TOTAL
IN EXCESS OF THE K DIMENSION AT
MAXIMUM MATERIAL CONDITION.
6. TERMINAL NUMBERS ARE SHOWN FOR
REFERENCE ONLY.
7. DIMENSION A AND B ARE TO BE
0.10 (0.004)M T U S V S
0.15 (0.006)T U S
N
2X
L/2
14
0.25 (0.010)
8
M
B
-U-
L
PIN 1
IDENT.
N
F
7
1
0.15 (0.006)T U S
DETAIL E
K
A
-V-
K1
J J1
SECTION N-N
-W-
C
0.10 (0.004)
-T- SEATING
D
PLANE
G
H
DIM
A
B
C
D
F
G
H
J
J1
K
K1
L
M
MILLIMETERS
MIN
MAX
4.90
5.10
4.30
4.50
—
1.20
0.05
0.15
0.50
0.75
0.65 BSC
0.50
0.60
0.09
0.20
0.09
0.16
0.19
0.30
0.19
0.25
6.40 BSC
0°
8°
INCHES
MIN MAX
0.193 0.200
0.169 0.177
— 0.047
0.002 0.006
0.020 0.030
0.026 BSC
0.020 0.024
0.004 0.008
0.004 0.006
0.007 0.012
0.007 0.010
0.252 BSC
0°
8°
DETAIL E
CASE 948G-01
ISSUE O
Figure 17. Case Outline Dimensions
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
20
Freescale Semiconductor
THIS PAGE INTENTIONALLY BLANK
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 2
Freescale Semiconductor
21
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Document Number: MC33493A
Rev. 2
03/2007
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