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19-2145; Rev 1; 8/03
200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands
General Description
The MAX2900-MAX2904 complete single-chip 200mW transmitters are designed for use in the 868MHz/ 915MHz frequency bands. The MAX2900/MAX2901/ MAX2902 are compliant with the FCC CFR47 part 15.247 902MHz to 928MHz ISM-band specifications. MAX2903/ MAX2904 are compliant with the ETSI EN330-220 specification for the European 868MHz ISM band. These transmitter ICs offer a high level of integration while minimizing the number of external components. This is achieved by full integration of the transmit modulator, power amplifier, RF VCO, 8-channel frequency synthesizer, and baseband PN sequence lowpass filter. By filtering the BPSK modulation, the spurious emissions are reduced, enabling up to eight independent transmit channels in the U.S. ISM band. Inputs are provided for spread-spectrum BPSK, ASK, and OOK. FM can be achieved by directly modulating the VCO. The devices are intended primarily for use with an external differential antenna.
Features
o Versions for U.S. 902MHz to 928MHz Band and European 868MHz Band o -7dBm to +23dBm Adjustable Differential RF Output Power o +23dBm Output Power at 4.5V, +20dBm Output Power at 3.0V o Support BPSK, OOK, ASK, and FM Modulations o Modulation Filter for Direct Sequence BPSK up to 8Mchips/s o Fully Integrated VCO with On-Chip Tank o Extremely Low Frequency Pulling for OOK Modulation (typ 60kHz peak, 5kHz RMS) o Integrated Frequency Synthesizer for up to 8 Channels (MAX2900) o +2.7V to +4.5V Supply Operation o Small 28-Pin QFN Package with Exposed Pad (5mm 5mm)
MAX2900-MAX2904
Applications
Automatic Meter Reading Wireless Security Systems/Alarms Wireless Sensors Wireless Data Networks Wireless Building Control
PART MAX2900EGI MAX2901EGI MAX2902EGI MAX2903EGI MAX2904EGI
Ordering Information
TEMP RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 28 QFN-EP* 28 QFN-EP* 28 QFN-EP* 28 QFN-EP* 28 QFN-EP*
*Exposed pad
Functional Diagrams/Pin Configurations
CPOUT
28 VTUNE GND VREG VCC1 RLPF
VCC5
27
D2
26
REFOUT VCC4
25 24
REFIN
23
OSC
22 21 D0 VTUNE GND VREG VCC1 RLPF 1 2
CPOUT
28
VCC5
27
DIV63 REFOUT VCC4
26 25 24
REFIN
23
OSC
22 21 VCO+ 20 VCO-
1
MAX2900
2 CP 3 4 5 6 7 8 GATE REG 8-CHANNEL SYNTHESIZER /4 19 N.C. 18 N.C. 17 RF+ 16 RF15 GND 10 11 12 13 14 3 4 5 6 7 8 REG 20 D1 CP
MAX2901/ MAX2903
19 DIVOUT DUALCHANNEL (/62 OR /63) SYNTHESIZER 18 GND 17 RF+ 16 RFGATE 15 GND 10 11 12 13 14
EN REFEN
EN REFEN
9
9
MODIN OOKIN
VCC2
VASK
LD
PWRSET VCC3
MODIN OOKIN
VCC2
VASK
LD
PWRSET VCC3
Functional Diagrams/Pin Configurations are continued at end of data sheet. ________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands MAX2900-MAX2904
ABSOLUTE MAXIMUM RATINGS
VCC to GND ...........................................................-0.3V to +5.0V Analog/Digital Input Voltage to GND..........-0.3V to (VCC + 0.3V) Analog/Digital Input Current ..............................................10A Continuous Power Dissipation (TA = +70C) 28-Pin QFN-EP (derate 28.5mW/C above +70C)............2W Operating Temperature Range ...........................-40C to +85C Junction Temperature .....................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. CAUTION! ESD SENSITIVE DEVICE
Part Selection Information
Five different versions are available. The versions differ by their frequency band of operation, and by the synthesizer's mode of operation. The MAX2900 has an internal 8-channel synthesizer. The MAX2901 and MAX2903 are dual-channel versions with a selectable internal synthesizer division ratio of 62 or 63. The MAX2901 operates in the 902MHz to 928MHz ISM band and the MAX2903 operates in the 867MHz to 870MHz European ISM band.
PART MAX2900EGI MAX2901EGI MAX2902EGI MAX2903EGI MAX2904EGI FREQUENCY RANGE (MHz) 902 to 928 902 to 928 902 to 928 867 to 870 867 to 870
The MAX2902 and MAX2904 require an off-chip frequency synthesizer. The MAX2902 operates in the 902MHz- 928MHz ISM band and MAX2904 operates in the 867MHz-870MHz European ISM band. The MAX2901-MAX2904 provide LO outputs to drive a receiver and/or an external synthesizer.
SYNTHESIZER Internal 8 selectable channels Internal 2 selectable channels Off-chip Internal 2 selectable channels Off-chip
LO OUTPUTS No Yes Yes Yes Yes
DC ELECTRICAL CHARACTERISTICS
(VCC = +2.7V to +4.5V, EN = OOKIN = REFEN = high, TA = -40C to +85C. Typical values are at VCC = +4.5V, TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER Supply Voltage Shutdown mode: EN = REFEN = low VCC = +4.0V VCC = +4.5V CONDITIONS MIN 2.7 -3 TYP 4.5 0.7 60 32 +3 MAX 4.5 10 200 40 UNITS V A
Synth mode: OOKIN = low (MAX2900/MAX2901/MAX2903 only) Supply Current Transmit mode with output matching optimized for +23dBm at +4.5V: PWRSET loaded with 22k resistor Transmit mode with output matching optimized for +20dBm at +3.0V: PWRSET loaded with 22k resistor TA = -40C to +85C
150
200 mA
TA = -40C to +85C
110
135
2
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200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands
DC ELECTRICAL CHARACTERISTICS (continued)
(VCC = +2.7V to +4.5V, EN = OOKIN = REFEN = high, TA = -40C to +85C. Typical values are at VCC = +4.5V, TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER CONDITIONS Transmit mode with output matching optimized for +17dBm at +3.0V: PWRSET loaded with 36k resistor Transmit mode with output matching optimized for +14dBm at +3.0V: PWRSET loaded with 51k resistor MIN -3 TYP +3 MAX UNITS
MAX2900-MAX2904
TA = +25C
75
Supply Current (continued)
TA = +25C
57
mA
Reference-only mode: EN = low PA standby mode: OOKIN = low (MAX2902/MAX2904 only) VCO Input Tuning Pin Current VREG VCO Regulator Voltage DIGITAL INPUT/OUTPUTS (PINS EN, REFEN, D0, D1, D2, MODIN, OOKIN, LD) Input Level High Input Level Low Input Bias Current Output Level High Output Level Low Output Current ANALOG CONTROL INPUTS (PINS PWRSET, RLPF, VASK) PWRSET Voltage RLPF Voltage VASK Input Impedance 100 -100 -10 VCC - 0.4 VCC - 0.5V VTUNE = +4.5V, TA = +25C
2 29 0.02 2.0
3 33 2 A V
V 0.5 10 V A V 0.4 100 1.2 1.2 220 400 V A V V k
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3
200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands MAX2900-MAX2904
AC ELECTRICAL CHARACTERISTICS
(MAX290_ EV kits. VCC = +2.7V to +4.5V, RRLPF = 68k, RPWRSET = 22k, fRF = 917.28MHz (MAX2900/MAX2901/MAX2902) or fRF = 868MHz (MAX2903/MAX2904), VASK = VREG, f REF = 14.56MHz (MAX2900/MAX2901/MAX2902) or f REF = 13.62MHz (MAX2903/MAX2904), chip rate on MODIN = 1.22Mbps, POUT = +23dBm, TA = -40C to +85C. Typical values are at VCC = +4.5V, TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER ANALOG INPUT PINS VTUNE Input Capacitance DIGITAL INPUT PINS Digital Input Pin Capacitance VCO AND SYNTHESIZERS SECTION RFOUT Frequency Range REFIN Reference Frequency Range REFDIV Fixed Reference Divider Ratio Main Divider Ratios PLL Comparison Frequency VCO Buffer Output Power REFDIV Fixed Reference Divider Ratio VCO Phase Noise VCO Tuning Gain VCO Frequency Pulling with OOK Modulation PLL Phase Noise REFOUT Voltage Swing CPOUT Charge Pump Current Reference Spurs Reference Input Voltage for Nominal Operation MODIN Frequency Range Modulation Filter Nominal 3dB Bandwidth Modulation Filter Final Attenuation Measured at 30MHz Carrier Suppression Noise Power Density At 960MHz (measured at RFOUT at +23dBm output power) 28 Using an external frequency reference 200 (MAX2900/MAX2901/MAX2902) (MAX2903/MAX2904) (MAX2900/MAX2901/MAX2902) (MAX2903/MAX2904) (MAX2900) Table 4 (MAX2900) (MAX2901/MAX2903) (MAX2900) (MAX2901/MAX2903) 300 differential load (MAX2901-MAX2904) (MAX2901/MAX2903) At 100kHz offset, measured at RFOUT, PLL loop BW = 5kHz VTUNE = +1.35V OOKIN clocked at 19kHz, internal (crystal) or external reference frequency Measured at RFOUT, 5kHz offset, PLL loop BW = 50kHz 100 500 -62 300 44 1 902 867 14 13 4 249 62 3.5 13 -12 1 -101 65 5 60 -96 86 1 dBc/Hz MHz/V kHz RMS kHz peak dBc/Hz mVp-p A dBc mV 3.64 917.28 868 14.56 13.78 4 928 870 15 14.5 4 256 63 3.75 15 MHz dBm MHz MHz 3 pF VTUNE = +1.35V 15 pF CONDITIONS MIN -3 TYP +3 MAX UNITS
BPSK, OOK MODULATOR, AND PA 1.2 1 41 28 -150 8 Mb/s MHz dB dB dBc/Hz
4
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200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands
AC ELECTRICAL CHARACTERISTICS (continued)
(MAX290_ EV kits. VCC = +2.7V to +4.5V, RRLPF = 68k, RPWRSET = 22k, fRF = 917.28MHz (MAX2900/MAX2901/MAX2902) or fRF = 868MHz (MAX2903/MAX2904), VASK = VREG, f REF = 14.56MHz (MAX2900/MAX2901/MAX2902) or f REF = 13.62MHz (MAX2903/MAX2904), chip rate on MODIN = 1.22Mbps, POUT = +23dBm, TA = -40C to +85C. Typical values are at VCC = +4.5V, TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER CONDITIONS PWRSET = 22k, VCC = +4.5V, TA = +25C RF Output Power PWRSET = 22k, VCC = +4.5V, TA = -40C to +85C PWRSET = 22k, VCC = +3.0V, TA = +25C RF Output Power Flatness Adjacent Channel Power Ratio Alternate Channel Power Ratio OOK Control Range ASK Output Power Adjustment Range RFOUT Rise and Fall Time ASK output power backoff relative to max power OOKIN = high, VASK = 0 OOKIN = high, VASK = 1V fRF = 900MHz to 930MHz (MAX2900/MAX2901/MAX2902) fRF = 867MHz to 870MHz PN sequence at 1.22MHz PN sequence at 1.22MHz 40 MIN -3 21 20.5 18 20 0.3 0.1 -17 -26 80 41 dB 16 1 -50 -51 -63 dBc < -70 s dBc dBc dB TYP 23.5 +3 25 25 21 dB dBm MAX UNITS
MAX2900-MAX2904
Square-wave signal applied on OOK At 2nd harmonic of RF output frequency with external matching network At 3rd harmonic of RF output frequency with external matching network At 4th harmonic of RF output frequency with external matching network Out of 902MHz to 928MHz band other than harmonics with external matching network (MAX2900/MAX2901/MAX2902) Out of 867MHz to 870MHz band other than harmonics with external matching network (MAX2903/MAX2904)
Spurious Emissions
< -70
Unlocked, Out-of-Band Spurious Output Level
Any condition when synthesizer unlocked (pin LD low) Modulation off, measured at 960MHz, any gain setting (MAX2900/MAX2901/MAX2902)
< -50 -126 -126 2:1 2:1 -120
dBm
Noise Level Out of Band Modulation off, measured at 900MHz, any gain setting (MAX2903/MAX2904) Output VSWR for Guaranteed Stability Maximum Allowable Output VSWR -120
dBm/Hz
Note 1: Devices are production tested at TA = +25C and +85C. Min/Max values are guaranteed by design and characterization over temperature and supply voltage. _______________________________________________________________________________________ 5
200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands MAX2900-MAX2904
Typical Operating Characteristics
(MAX290_ EV kits. VCC = +4.5V, fRF = 917.28MHz (MAX2900/MAX2901/MAX2902) or fRF = 868MHz (MAX2903/MAX2904), RRLPF = 68k, RPWRSET = 22k, VASK = VREG, fREF = 14.56MHz (MAX2900/MAX2901/MAX2902) or fREF = 13.78MHz (MAX2903/MAX2904), chip rate on MODIN = 1.22 Mbps, RF output matching network optimized for +23dBm, V CC = 4.5V, T A = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. VCC
MAX2900 toc01
SHUTDOWN CURRENT vs. VCC
MAX2900 toc02
OUTPUT POWER vs. VCC
MAX2900 toc03
160 150 SUPPLY CURRENT (mA) 140 130 120 110 100 90 80 2.5 3.0 3.5 VCC (V) 4.0 TA = -40C TA = +85C TA = +25C
100
26
SHUTDOWN CURRENT (A)
24 OUTPUT POWER (dBm) TA = +25C
TA = +85C
10
22
TA = +85C 1
TA = -40C 20
18 TA = -40C 0.1 4.5 2.5 3.0 3.5 VCC (V) 4.0 4.5 TA = +25C 16 2.5 3.0 3.5 VCC (V) 4.0 4.5
VCO PHASE NOISE AT 917.28MHz
MAX2900 toc04
VCO SUPPLY PUSHING vs. VCC
MAX2900 toc05
PLL LOCK TIME
MAX2900 toc06
-40dBc/Hz
918.0 917.5 OUTPUT FREQUENCY (MHz) 917.0 916.5 916.0 915.5
100kHz
20kHz/div
-140dBc/Hz FREQUENCY OFFSET (MHz)
915.0 2.5 3.0 3.5 VCC (V) 4.0 4.5
-100kHz START 0s
STOP 30s
LOWPASS FILTER 3-dB RESPONSE vs. RRLPF
MAX2900 toc07
BPSK MODULATION OUTPUT vs. TIME
MAX2900 toc08
RF POWER vs. FREQUENCY (MAX2900/MAX2901/MAX2902)
A B C RF POWER (dBm) 23 22 21 20 19 E D F A: VCC = 4.5V, TA = -40C B: VCC = 4.5V, TA = +25C C: VCC = 4.5V, TA = +85C D: VCC = 2.7V, TA = -40C E: VCC = 2.7V, TA = +25C F: VCC = 2.7V, TA = +85C
MAX2900 toc09
3500 LOWPASS FILTER 3-dB BANDWIDTH (kHz) 3000 2500 2000
225deg
25 24
45deg/div 1500 1000 500 0 10 20 30 40 RRLPF (k) 50 60 70 -225deg START 0s STOP 40s
18 900 905 910 915 920 925 930 FREQUENCY (MHz)
6
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200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands
Typical Operating Characteristics (continued)
(MAX290_ EV kits. VCC = +4.5V, fRF = 917.28MHz (MAX2900/MAX2901/MAX2902) or fRF = 868MHz (MAX2903/MAX2904), RRLPF = 68k, RPWRSET = 22k, VASK = VREG, fREF = 14.56MHz (MAX2900/MAX2901/MAX2902) or fREF = 13.78MHz (MAX2903/MAX2904), chip rate on MODIN = 1.22 Mbps, RF output matching network optimized for +23dBm, V CC = 4.5V, T A = +25C, unless otherwise noted.)
RF POWER vs. FREQUENCY (MAX2903/MAX2904)
RF OUTPUT MATCHING OPTIMIZED FOR +14dBm OUTPUT AT VCC = +3.0V VCC = +3.6V
MAX2900 toc10
MAX2900-MAX2904
OUTPUT SPECTRUM WITH 600kHz SQUARE WAVE INPUT AT MODIN
MAX2900 toc11
OUTPUT SPECTRUM WITH PN SEQUENCE AT 1.22MHz AT MODIN
MKR 917.35MHz 8.17dBm
MAX2900 toc12
17
30dBm
16 RF POWER (dBm)
MKR 917.31MHz -16.33dBm
30dBm
15 VCC = +3.0V 14 VCC = +2.7V 13 10dB/div 10dB/div
12 860 864 868 FREQUENCY (MHz) 872 876
-70dBm CENTER 917.28MHz
SPAN 20MHz
-70dBm CENTER 917.28MHz
SPAN 20MHz
RF OUT RISE AND FALL TIME TRANSIENT WITH SQUARE OOK
Tr Tf
MAX2900 toc13
RF OUT RISE AND FALL TIME TRANSIENT WITH SQUARE ASK
MAX2900 toc14
SPURIOUS LEVEL FROM DC TO 7TH HARMONIC
MKR 910MHz 23.17dBm
MAX2900 toc15
0dBVp-p
22dBVp-p
30dBm
Tr
Tf 10dB/div
10dB/div
10dB/div
-100dBVp-p START 46s
STOP 86s
-78dBVp-p
-70dBm START 45s STOP 85s START 0Hz STOP 7GHz
SPURIOUS LEVEL BETWEEN 50MHz FROM CARRIER FREQUENCY
MAX2900 toc16
TRANSMITTER EFFICIENCY vs. RPWRSET
40 35 30 25 20 15 A B C D E F
MAX2900 toc17
30dBm
45 TRANSMITTER EFFICIENCY (%)
10dB/div
-70dBm CENTER 917.28MHz SPAN 100MHz
10 14
A: VCC = 4.5V, TA = -40C B: VCC = 4.5V, TA = +25C C: VCC = 4.5V, TA = +85C D: VCC = 2.7V, TA = -40C E: VCC = 2.7V, TA = +25C F: VCC = 2.7V, TA = +85C 18 22 26 30 34 38
RPWRSET (k)
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7
200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands MAX2900-MAX2904
Pin Description
MAX2900 1 2 3 PIN MAX2901 MAX2903 1 2 3 MAX2902 MAX2904 1 2 3 NAME VTUNE GND VREG PIN TYPE Analog Input Supply Pin Analog Input/Output FUNCTION VCO tuning voltage input Ground Regulated voltage output to supply the VCO. Bypass with a 0.01F capacitor to GND as close to the part as possible. Power supply pin for VCO circuits. Bypass with a 1000pF and a 10F capacitor to GND as close to the part as possible.
4
4
4
VCC1
Supply Pin
5 6 7 8 9
5 6 7 8 9
5 6 7 8 9
RLPF EN REFEN MODIN OOKIN
Analog Input Resistor to ground on this pin sets the Resistor to Ground modulation filter bandwidth. Digital Input Digital Input Digital Input Digital Input Chip-enable digital input pin. Set EN low maintain the chip in power-down mode. Enable for crystal oscillator and frequency reference buffer. BPSK modulation input On-off keying modulation. On state = high. Power supply pin for internal RF buffer circuits. Bypass with a 100pF and a 0.01F capacitor to GND as close to the part as possible. ASK voltage input pin Lock detector output digital pin. Level is high when PLL is inside lock range.
10
10
10
VCC2
Supply
11 12 -- 13
11 12 -- 13
11 -- 12 13
VASK LD D.C. PWRSET
Analog Voltage Input Digital Output
Do NOT Connect -- Analog Input Current input set to adjust output power. Resistor to Ground Supply Power supply pin for RF power amplifier circuits. Bypass with a 100pF capacitor to GND as close to the part as possible.
14
14
14
VCC3
8
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200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands MAX2900-MAX2904
Pin Description (continued)
PIN MAX2900 15 16, 17 18 -- -- 19 -- -- 20 21 22 MAX2901 MAX2903 15 16, 17 -- 18 -- -- 19 20, 21 -- -- 22 MAX2902 MAX2904 15 16, 17 -- -- 18 19 -- 20, 21 -- -- 22 NAME GND RF-, RF+ N.C. GND D.C. N.C. DIVOUT VCO-, VCO+ D1 D0 OSC PIN TYPE Supply Pin RF Output Not Connected Supply Pin Do Not Connect Not Connected ECL Output Open Collector RF Digital Input Digital Input Analog Input Analog Voltage Input Ground RF differential output, open-collector type -- Ground -- -- Divider output VCO output (differential) Channel selection bit 1 Channel selection bit 0 Crystal oscillator connection. See Typical Operating Circuit. Reference input pin analog (can be used as input or as crystal oscillator driver). See Typical Operating Circuit. Power-supply pin for the synthesizer circuits. Bypass with a 1000pF capacitor to GND as close to the part as possible. Power-supply pin for the digital circuits. Bypass with a 100pF capacitor to GND as close to the part as possible. Buffered clock analog output pin Channel selection bit 2 Division ratio selections (division ratio = 62 when DIV63 = high; division ratio = 63 when DIV63 = low). -- Power-supply pin for charge pump circuits. Bypass with a 100pF capacitor to GND as close to the part as possible. Power-supply pin. Bypass with a 100pF capacitor to GND as close to the part as possible. Charge pump output pin -- Back side of package is connected to ground. FUNCTION
23
23
23
REFIN
24
24
--
VCC4
Supply Pin
-- 25 26 -- -- 27
-- 25 -- 26 -- 27
24 25 -- -- 26 --
VCC4 REFOUT D2 DIV63 N.C. VCC5
Supply Pin Analog Output Digital Input Digital Input Not Connected Supply Pin
-- 28 -- GROUND
-- 28 -- GROUND
27 -- 28 GROUND
VCC5 CPOUT D.C. GROUND
Supply Pin Analog Output Do Not Connect Electrical Ground
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9
200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands MAX2900-MAX2904
Detailed Description
Principles of Operation
When EN goes high, the reference and the VCO start while the PA stays in the off mode. For MAX2900/ MAX2901/MAX2903, the PLL also starts when EN goes high. After the lock-detect pin LD goes high, the PA is set to stand-by mode. For the MAX2902/MAX2904, the VCO loop has to be closed by using an external synthesizer. After this, pulling OOKIN high turns on the PA. The internal modulation filter smoothes the power ramp-up of the PA. The modulation filter BW is typically 0.8MHz, used for a 1.22Mbps chip rate, and can be adjusted by varying RLPF. A high value can be used for RLPF to get a slow PA ramping up when BPSK is not used. The reference blocks can be turned on separately (and earlier) by pulling REFEN high, to allow the crystal frequency to settle. The device supports various modulation modes: * BPSK, filtered by the internal modulation filter, is obtained through the MODIN pin. This is the preferred mode of operation for MAX2900. OOK is obtained digitally with the OOKIN pin. ASK is obtained through the ASK pin.
TO INTERNAL CONTROL CIRCUIT
3) Transmit mode: Pin EN and REFEN are high. If output pin LD is high, the device is ready to transmit. When OOKIN is high, the power amplifier is turned on. The current consumption varies between 50mA and 120mA, depending on the output power requested by the combination of the OOK duty cycle, the PWRSET value, and output matching circuit. 4) Reference Only mode: This mode enables the use of the crystal reference from the IC to drive the external logic ICs. To obtain this mode, set the REFEN pin high and EN low. In this mode, only the reference circuit turns on, the crystal oscillator starts, and the clock is present at the REFOUT pin. The current consumption remains much lower than that in the SYNTH mode because the VCO, synthesizer, and PA standby circuits are off. When EN goes high, the IC goes into the SYNTH mode.
Synthesizer Programming
The three pins D0-D2 (MAX2900) and DIV63 (MAX2901/ MAX2903) are used as digital entries to program the synthesizer division ratios. Tables 4 and 5 show the division ratios obtained for the various pin logic levels.
* * * *
FM is imposed on the VCO or the reference. FM is the preferred mode of operation for the MAX2903/MAX2904 due to the narrowband operation common in Europe. The maximum output power is set by the output matching network and the external biasing resistor on the PWRSET pin. For the MAX2901-MAX2904, differential LO outputs are provided to drive a companion receiver and/or an external synthesizer.
PIN PWRSET 100
1.2V
INTERNAL CIRCUITS
EXTERNAL RESISTOR
Figure 1. PIN PWRSET Equivalent Circuit
Power-Up Modes
The circuit has four modes of operations, defined as follows: 1) Shutdown mode: Pin EN and REFEN are low, all functions are off, and the current consumption is leakage only. 2) Synth mode: Pin EN and REFEN are high, pin OOKIN is low. The reference circuits, VCO, and synthesizer are turned on. The power amplifier is in stand-by mode. Total current is less than 50mA. Note that as long as the LD pin is not going high, indicating that the PLL is unlocked, OOKIN high is ignored.
Analog Input Control Pins
The two pins PWRSET and VASK are analog inputs used to control the power of the transmitter. The equivalent input schematics are defined in Figures 1, 2, and 3. The PWRSET pin sets the biasing of the amplification chain. Because the last stage of the amplifier operates in saturation, the output power mostly depends on the load and supply voltage. The purpose of the PWRSET resistor is to achieve optimum biasing (and therefore efficiency) for various maximum output power configurations. For a given application with a known operating voltage and peak power, a fixed value of resistor is determined. The output power range of -7dBm to +23dBm at 4.5V is obtained by choosing a combination of output load line and the resistor on PWRSET; 22k is
10
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200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands
used on the EV kit board for +23dBm output power at 4.5V, and 22k is also recommended for +20dBm output power at +3.0V. For +17dBm at 3.0V, 36k is recommended. The current consumption, efficiency, and distortion in the amplification chain are affected by the choice of the resistor RPWRSET, offering a lot of design flexibility.
TO VREG (2.1V) TO INTERNAL CONTROL CIRCUIT
The RLPF pin sets the bandwidth of the modulation filter. The default filter bandwidth, obtained with a 68k resistor, is for 1.2Mchips/s. The bandwidth is increased to accommodate 5Mchips/s by decreasing the resistor value to about 26k. The minimum value for the resistor is 12k, which generates the maximum filter bandwidth. A higher value can be used in FM mode to set up a slow ramp-up time for the PA.
MAX2900-MAX2904
Data Filter Characteristics
The data filter approximates a 3rd-order Butterworth filter. The 3dB cut-off frequency is adjusted through the resistor on pin RLPF, which controls the first two poles of the filter (the last high-frequency pole is fixed and set around 10MHz). The filter is adjustable in a range from approximately 700kHz to 7MHz. With the nominal setting (3dB cut off at 0.8MHz), the filter attenuation is 10dB at 3.6MHz. If used with a BPSK at 1.22MHz, this provides about 30dB of modulation rolloff at 3.6MHz. Hence, a significant channelization effect is obtained. In the wideband setting (3dB cut off at 5MHz), the attenuation at 30MHz is still 30dB, helping to pass the FCC spurious emissions at 960MHz.
PIN VASK >200k INTERNAL CIRCUITS
EXTERNAL RESISTOR BRIDGE
1.5V
Figure 2. PIN VASK Equivalent Circuit
The VASK pin is an input to the internal gain control circuitry. The gain control is greater than 30dB over the full range of input voltages from 0 to VREG = 2.1V. This input is used for ASK modulation. At 1V, a typical 15dB attenuation is obtained from the peak power. When this input is not used, connect VASK to VREG. The RLPF input controls the modulation filter center frequency.
TO INTERNAL CONTROL CIRCUIT
PIN RLPF 100
1.2V
INTERNAL CIRCUITS
EXTERNAL RESISTOR
Figure 3. PIN RLPF Equivalent Circuit
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11
200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands MAX2900-MAX2904
Table 1. MAX2900 Power-Up Modes
LOGIC LEVEL REFEN 0 1 1 1 EN 0 0 1 1 OOKIN X X 0 1 REFERENCE Off On On On INTERNAL BLOCK STATUS VCO MOD FILTER Off Off On On SYNTHESIZER Off Off On On PA Off Off Off On only after LD goes high
Table 2. MAX2901/MAX2903 Power-Up Modes
REFEN 0 1 1 1 EN 0 0 1 1 OOKIN X X 0 1 REFERENCE Off On On On VCO MOD FILTER Off Off On On SYNTHESIZER Off Off On On PA Off Off Off On only after LD goes high
Table 3. MAX2902/MAX2904 Power-Up Modes
REFEN 0 1 0 1 0 1 EN 0 0 1 1 1 1 OOKIN X 0 0 0 1 1 REFERENCE Off On Off On Off On VCO MOD FILTER Off Off On On On On PA Off Off Off Off On On
Table 4. MAX2900 Synthesizer Programming
D0 0 0 0 0 1 1 1 1 D1 1 1 0 0 1 1 0 0 D2 1 0 1 0 1 0 1 0 DIVISION RATIO 249 250 251 252 253 254 255 256
Table 5. MAX2901/MAX2903 Synthesizer Programming
DIV 63 0 1 DIVISION RATIO 62 63
12
______________________________________________________________________________________
C25 EXT REFERENCE (OPT) C23
REFOUT
C28 C24
C26
Y1 (OPT)
WBFM (OPT)
VCC5
REFOUT
CPOUT D2
26 D0 1 21 D0 D1 C15 L3 18 N.C. C31 RLPF 5 17 RF6 7 8 9 10 11 12 13 14 GATE 15 GND L2 16 L1 C32 L4 C16 C34 EN REFEN RF+ C33 L5 25 24 23 22
VCC4 OSC
R3 28 27 C35 VTUNE
R1
C2
C1
R4
MAX2900
20 CP /4 19 N.C. REG 8-CHANNEL SYNTHESIZER D1
GND 2 3 4 VREG
C3
C4 VCC1 C13
REFIN
LOOP ANTENNA
R5
VCC2 VASK LD VREG
R6 C8 ASK (OPT)
VCC3
C12 VCC_DRV
VCC_PA
OOK
R7
R8
MAX2900-MAX2904
______________________________________________________________________________________
Typical Operating Circuits
MAX2900 TYPICAL OPERATING CIRCUIT
PWRSET
C18
MODIN (PN)
MODIN OOKIN
200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands
13
MAX2900-MAX2904
VCC5
REFOUT
CPOUT VCC4 OSC
22 24 23 R1 28 27 26 25
R3
DIV63
REFIN
OOK
R6 C8
VREG
ASK (OPT)
PWRSET
200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands
14
C25 EXT REFERENCE /FM INPUT C23
REFOUT
C28 C24
C26
Y1
WBFM (OPT)
VCC
R11 R10 C37
21 20 DIVOUT 19 C15 L3 C31 17 16 RFGND L2 RF+ L1 C32 L4 C16 C34 C33 VCOVCO+
C2 C35 1 GND 2 CP VREG 3 4 5 6 7 8 9 10 11 12 13 14 GATE 15 REG 18 GND VTUNE
C1
R4
MAX2901/ MAX2903
VCOOUT
C3
C4 VCC1 C13 RLPF R5 REFEN EN DUALCHANNEL (/62 OR /63) SYNTHESIZER
L5
LOOP ANTENNA
VCC2 VASK LD MODIN OOKIN
VCC3
C12 VCC_DRV
VCC_PA
MODIN (PN)
C18
______________________________________________________________________________________
R7 R8
Typical Operating Circuits (continued)
MAX2901/MAX2903 TYPICAL OPERATING CIRCUIT
REFFREQ /FM
CPOUT REFIN
C28 C26
WBFM (OPT)
VCC D.C. REFOUT
25 24 23 22
VCC5 N.C. VCC4 REFIN OSC R11
21 20 VCOVCO+ 27 26
R3 28
R1
1GHz FREQUENCY SYNTH
R10 C37 RFIN VCOOUT
C15 L3
C2 C35 1 2 3 4 REG 18 D.C. C31 17 RF6 7 8 9 10 11 12 13 14 GATE 15 GND L2 16 C32 RF+ L1 L4 C16 C34 C33 L5 19 N.C. GND VREG VTUNE
C1
R4
C3
C4 VCC1 C13 RLPF 5 R5 REFEN EN
MAX2902/ MAX2904
LOOP ANTENNA
VCC2 VASK D.C. VREG
R6 C8 ASK (OPT) C18
VCC3
C12 VCC_DRV
VCC_PA
OOK
R7
R8
MAX2900-MAX2904
______________________________________________________________________________________
Typical Operating Circuits (continued)
MAX2902/MAX2904 TYPICAL OPERATING CIRCUIT
PWRSET
MODIN (PN)
MODIN OOKIN
200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands
15
200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands MAX2900-MAX2904
Functional Diagrams/ Pin Configurations (continued)
TRANSISTOR COUNT: 898
D.C.
28 VTUNE GND VREG VCC1 RLPF
Chip Information
VCC5
27
N.C.
26
REFOUT VCC4
25 24
REFIN
23
OSC
22 21 VCO+ 20 VCO19 N.C.
1 2 3 4 5 6 7 8 GATE REG
MAX2902/ MAX2904
18 D.C. 17 RF+ 16 RF15 GND
EN REFEN
9
10
11
12
13
14
MODIN OOKIN
VCC2
VASK
D.C.
PWRSET VCC3
16
______________________________________________________________________________________
200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
32L QFN.EPS
MAX2900-MAX2904
______________________________________________________________________________________
17
200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands MAX2900-MAX2904
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
18 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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