MAXIM MAX2900, MAX2904 User Manual

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.

Applications

Automatic Meter Reading Wireless Security Systems/Alarms Wireless Sensors Wireless Data Networks Wireless Building Control

Features

♦ Versions for U.S. 902MHz to 928MHz Band and

European 868MHz Band

♦ -7dBm to +23dBm Adjustable Differential RF

Output Power

♦ +23dBm Output Power at 4.5V, +20dBm Output

Power at 3.0V

♦ Support BPSK, OOK, ASK, and FM Modulations ♦ Modulation Filter for Direct Sequence BPSK up to

8Mchips/s

♦ Fully Integrated VCO with On-Chip Tank ♦ Extremely Low Frequency Pulling for OOK

Modulation (typ 60kHz peak, 5kHz RMS)

♦ Integrated Frequency Synthesizer for up to

8 Channels (MAX2900)

♦ +2.7V to +4.5V Supply Operation ♦ Small 28-Pin QFN Package with Exposed Pad

(5mm ✕5mm)

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for

868MHz/915MHz ISM Bands

________________________________________________________________ Maxim Integrated Products 1

810911121314

27 25 24 23 22

REFEN

RLPF

VCC1

VREG

GND

VTUNE

GND

RF-

RF+

GND

DIVOUT

VCO-

VCO+

OSC

REFIN

VCC4

REFOUT

DIV63

VCC5

CPOUT

VCC3

PWRSET

VASK

VCC2

OOKIN

MODIN

DUAL-

CHANNEL

(/62 OR /63)

SYNTHESIZER

GATE

REG

MAX2901/

MAX2903

Functional Diagrams/Pin Configurations

19-2145; Rev 2; 12/07

Ordering Information

*Exposed pad

PART

TEMP RANGE

PIN-PACKAGE

MAX2900EGI -40°C to +85°C 28 QFN-EP*

MAX2901EGI -40°C to +85°C 28 QFN-EP*

MAX2902EGI -40°C to +85°C 28 QFN-EP*

MAX2903EGI -40°C to +85°C 28 QFN-EP*

MAX2904EGI -40°C to +85°C 28 QFN-EP*

Functional Diagrams/Pin Configurations are continued at end of data sheet.

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

VCC5

CPOUT

27 25 24 23 22

VTUNE

GND

VREG

VCC1

RLPF

REFEN

MODIN

MAX2900

REG

GATE

810911121314

OOKIN

REFOUT

8-CHANNEL

SYNTHESIZER

VASK

VCC4

÷4

VCC2

REFIN

PWRSET

OSC

VCC3

N.C.

RF+

RF-

GND

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

DC ELECTRICAL CHARACTERISTICS

(VCC= +2.7V to +4.5V, EN = OOKIN = REFEN = high, TA= -40°C to +85°C. Typical values are at VCC= +4.5V, TA= +25°C, unless otherwise noted.) (Note 1)

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.

VCCto GND...........................................................-0.3V to +5.0V

Analog/Digital Input Voltage to GND..........-0.3V to (V

+ 0.3V)

Analog/Digital Input Current ..............................................±10µA

Continuous Power Dissipation (T

= +70°C)

28-Pin QFN-EP (derate 28.5mW/°C above +70°C)............2W

Operating Temperature Range ...........................-40°C to +85°C

Junction Temperature .....................................................+150°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

PARAMETER CONDITIONS

UNITS

Supply Voltage

4.5 V

Shutdown mode: EN = REFEN = low

µA

Synth mode: OOKIN = low (MAX2900/MAX2901/MAX2903 only)

32 40

Transmit mode with output matching optimized for +23dBm at +4.5V: PWRSET loaded with 22kΩ resistor

= -40°C

to +85°C

Supply Current

Transmit mode with output matching optimized for +20dBm at +3.0V: PWRSET loaded with 22kΩ resistor

= -40°C

to +85°C

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.

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.

PART

FREQUENCY RANGE (MHz)

SYNTHESIZER LO OUTPUTS

MAX2900EGI 902 to 928

MAX2901EGI 902 to 928

Yes

MAX2902EGI 902 to 928 Off-chip Yes

MAX2903EGI 867 to 870

Yes

MAX2904EGI 867 to 870 Off-chip Yes

Part Selection Information

CAUTION! ESD SENSITIVE DEVICE

Internal 8 selectable channels

Internal 2 selectable channels

MIN -3σ TYP +3σ MAX

2.7 4.5

VCC = +4.0V 0.7

VCC = +4.5V

150 200

110 135

200

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for

868MHz/915MHz ISM Bands

_______________________________________________________________________________________ 3

DC ELECTRICAL CHARACTERISTICS (continued)

(VCC= +2.7V to +4.5V, EN = OOKIN = REFEN = high, TA= -40°C to +85°C. Typical values are at VCC= +4.5V, TA= +25°C, unless otherwise noted.) (Note 1)

PARAMETER CONDITIONS

MIN

-3σ

TYP

+3σ

MAX

UNITS

Transmit mode with output matching optimized for +17dBm at +3.0V: PWRSET loaded with 36kΩ resistor

Transmit mode with output matching optimized for +14dBm at +3.0V: PWRSET loaded with 51kΩ resistor

Reference-only mode: EN = low 2 3

Supply Current (continued)

PA standby mode: OOKIN = low (MAX2902/MAX2904 only)

29 33

VCO Input Tuning Pin Current VTUNE = +4.5V, TA = +25°C

2µA

VREG VCO Regulator Voltage

D IG IT A L IN PU T /O U T PU T S ( P IN S E N , RE FE N , D 0, D 1, D 2, M O D IN , O OKIN , LD )

Input Level High

Input Level Low 0.5 V

Input Bias Current

10 µA

Output Level High

Output Level Low 0.4 V

Output Current

µA

ANALOG CONTROL INPUTS (PINS PWRSET, RLPF, VASK)

PWRSET Voltage

RLPF Voltage

VASK Input Impedance

100

220

400

kΩ

TA = +25°C

0.02

2.0

- 0.5V

-10

- 0.4

-100 100

1.2

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands

4 _______________________________________________________________________________________

AC ELECTRICAL CHARACTERISTICS

(MAX290_ EV kits. VCC= +2.7V to +4.5V, R

RLPF

= 68kΩ, R

PWRSET

= 22kΩ, fRF= 917.28MHz (MAX2900/MAX2901/MAX2902) or f

= 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, P

OUT

= +23dBm, TA= -40°C to +85°C. Typical values are at VCC= +4.5V,

= +25°C, unless otherwise noted.) (Note 1)

PARAMETER CONDITIONS

MIN

-3σ

TYP

+3σ

MAX

U N I T S

ANALOG INPUT PINS

VTUNE Input Capacitance VTUNE = +1.35V 15 p F

DIGITAL INPUT PINS

Digital Input Pin Capacitance 3 p F

VCO AND SYNTHESIZERS SECTION

(MAX2900/MAX2901/MAX2902)

RFOUT Frequency Range

(MAX2903/MAX2904)

M H z

(MAX2900/MAX2901/MAX2902) 14

REFIN Reference Frequency Range

(MAX2903/MAX2904) 13

M H z

REFDIV Fixed Reference Divider Ratio

(MAX2900) 4 4 4

Table 4 (MAX2900)

Main Divider Ratios

(MAX2901/MAX2903) 62 63

(MAX2900)

PLL Comparison Frequency

(MAX2901/MAX2903) 13 15

M H z

VCO Buffer Output Power

-12

d Bm

REFDIV Fixed Reference Divider Ratio

(MAX2901/MAX2903) 1 1 1

VCO Phase Noise

At 100kHz offset, measured at RFOUT, PLL loop BW = 5kHz

d Bc/H z

(MAX2900/MAX2901/MAX2902) 44 65 86

VCO Tuning Gain

(MAX2903/MAX2904) 85

M H z/V

kH z RM S

VCO Frequency Pulling with OOK Modulation

OOKIN clocked at 19kHz, internal (crystal) or external reference frequency 60

kH z p eak

PLL Phase Noise

Measured at RFOUT, 5kHz offset, PLL loop BW = 50kHz

-96

d Bc/H z

REFOUT Voltage Swing

m V p - p

CPOUT Charge Pump Current

µA

Reference Spurs -62 d Bc

Reference Input Voltage for Nominal Operation

Using an external frequency reference

m V

BPSK, OOK MODULATOR, AND PA

MODIN Frequency Range 1.2 8

M b /s

Modulation Filter Nominal 3dB Bandwidth

M H z

Modulation Filter Final Attenuation

Measured at 30MHz 28 41 d B

Carrier Suppression 28 d B

Noise Power Density

At 960MHz (measured at RFOUT at +23dBm output power)

d Bc/H z

300Ω d i ffer enti al l oad ( M AX 2901–M AX 2904)

902 917.28 928

867 868 870

14.56

13.78 14.5

249 256

3.5 3.64 3.75

100

200 300

-101

500

-150

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for

868MHz/915MHz ISM Bands

_______________________________________________________________________________________ 5

AC ELECTRICAL CHARACTERISTICS (continued)

(MAX290_ EV kits. VCC= +2.7V to +4.5V, R

RLPF

= 68kΩ, R

PWRSET

= 22kΩ, fRF= 917.28MHz (MAX2900/MAX2901/MAX2902) or f

= 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, P

OUT

= +23dBm, TA= -40°C to +85°C. Typical values are at VCC= +4.5V,

= +25°C, unless otherwise noted.) (Note 1)

PARAMETER CONDITIONS

U N I T S

PWRSET = 22kΩ, VCC = +4.5V, T

= +25°C

PWRSET = 22kΩ, VCC = +4.5V, T

= -40°C to +85°C

RF Output Power

P WRS E T = 22kΩ , V

C C

= + 3.0V , TA = + 25°C

d Bm

fRF = 900MHz to 930MHz (MAX2900/MAX2901/MAX2902)

0.3

RF Output Power Flatness

= 867MHz to 870MHz

0.1

d B

Adjacent Channel Power Ratio PN sequence at 1.22MHz -17 d Bc

Alternate Channel Power Ratio PN sequence at 1.22MHz -26 d Bc

OOK Control Range 40 80 d B

OOKIN = high, VASK = 0

ASK Output Power Adjustment Range

ASK output power back-

OOKIN = high, VASK = 1V

d B

RFOUT Rise and Fall Time Square-wave signal applied on OOK 1 µs

At 2nd harmonic of RF output frequency with external matching network

-50

At 3rd harmonic of RF output frequency with external matching network

-51

At 4th harmonic of RF output frequency with external matching network

-63

Out of 902MHz to 928MHz band other than harmonics with external matching network (MAX2900/MAX2901/MAX2902)

Spurious Emissions

Out of 867MHz to 870MHz band other than harmonics with external matching network (MAX2903/MAX2904)

d Bc

Unlocked, Out-of-Band Spurious Output Level

Any condition when synthesizer unlocked (pin LD low)

d Bm

Modulation off, measured at 960MHz, any

Noise Level Out of Band

Modulation off, measured at 900MHz, any gain setting (MAX2903/MAX2904)

d Bm /H z

Output VSWR for Guaranteed Stability

2:1

M axi m um Al l ow ab l e Outp ut V S WR

2:1

Note 1: Devices are production tested at TA= +25°C and +85°C. Min/Max values are guaranteed by design and characterization

over temperature and supply voltage.

off relative to max power

gain setting (MAX2900/MAX2901/MAX2902)

MIN -3σ TYP +3σ MAX

21 23.5 25

20.5 25

< -70

< -50

-126 -120

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands

6 _______________________________________________________________________________________

Typical Operating Characteristics

(MAX290_ EV kits. VCC= +4.5V, fRF= 917.28MHz (MAX2900/MAX2901/MAX2902) or fRF= 868MHz (MAX2903/MAX2904), R

RLPF

68kΩ, R

PWRSET

= 22kΩ, VASK = VREG, f

REF

= 14.56MHz (MAX2900/MAX2901/MAX2902) or f

REF

= 13.78MHz (MAX2903/MAX2904),

chip rate on MODIN = 1.22 Mbps, RF output matching network optimized for +23dBm, V

= 4.5V, TA= +25°C, unless

otherwise noted.)

SUPPLY CURRENT vs. V

MAX2900 toc01

VCC (V)

SUPPLY CURRENT (mA)

4.03.53.0

100

110

120

130

140

150

160

2.5 4.5

TA = +85°C

TA = +25°C

TA = -40°C

SHUTDOWN CURRENT vs. V

MAX2900 toc02

VCC (V)

SHUTDOWN CURRENT (μA)

4.03.53.0

100

0.1

2.5 4.5

TA = +85°C

TA = +25°C

TA = -40°C

OUTPUT POWER vs. V

MAX2900 toc03

VCC (V)

OUTPUT POWER (dBm)

4.03.53.0

2.5 4.5

TA = +85°C

TA = +25°C

TA = -40°C

VCO PHASE NOISE AT 917.28MHz

MAX2900 toc04

-40dBc/Hz

-140dBc/Hz FREQUENCY OFFSET (MHz)

VCO SUPPLY PUSHING vs. V

MAX2900 toc05

VCC (V)

OUTPUT FREQUENCY (MHz)

4.03.53.0

915.5

916.0

916.5

917.0

917.5

918.0

915.0

2.5 4.5

PLL LOCK TIME

MAX2900 toc06

100kHz

-100kHz START 0s

20kHz/div

STOP 30μs

LOWPASS FILTER 3-dB RESPONSE

vs. R

RLPF

MAX2900 toc07

RLPF

(kΩ)

LOWPASS FILTER 3-dB BANDWIDTH (kHz)

6050403020

500

1000

1500

2000

2500

3000

3500

10 70

BPSK MODULATION OUTPUT vs. TIME

MAX2900 toc08

225deg

-225deg

45deg/div

START 0s

STOP 40μs

RF POWER vs. FREQUENCY

(MAX2900/MAX2901/MAX2902)

MAX2900 toc09

FREQUENCY (MHz)

RF POWER (dBm)

925920915910905

900 930

A B

A: VCC = 4.5V, TA = -40°C B: V

= 4.5V, TA = +25°C

C: V

= 4.5V, TA = +85°C

D: V

= 2.7V, TA = -40°C

E: V

= 2.7V, TA = +25°C

F: V

= 2.7V, TA = +85°C

Typical Operating Characteristics (continued)

(MAX290_ EV kits. VCC= +4.5V, fRF= 917.28MHz (MAX2900/MAX2901/MAX2902) or fRF= 868MHz (MAX2903/MAX2904), R

RLPF

68kΩ, R

PWRSET

= 22kΩ, VASK = VREG, f

REF

= 14.56MHz (MAX2900/MAX2901/MAX2902) or f

REF

= 13.78MHz (MAX2903/MAX2904),

chip rate on MODIN = 1.22 Mbps, RF output matching network optimized for +23dBm, V

= 4.5V, TA= +25°C, unless

otherwise noted.)

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for

868MHz/915MHz ISM Bands

_______________________________________________________________________________________ 7

RF POWER vs. FREQUENCY

(MAX2903/MAX2904)

MAX2900 toc10

FREQUENCY (MHz)

RF POWER (dBm)

872868864

860 876

VCC = +3.6V

VCC = +3.0V

VCC = +2.7V

RF OUTPUT MATCHING OPTIMIZED FOR +14dBm OUTPUT AT V

= +3.0V

OUTPUT SPECTRUM WITH 600kHz

SQUARE WAVE INPUT AT MODIN

MAX2900 toc11

30dBm

-70dBm

10dB/div

MKR

917.31MHz

-16.33dBm

CENTER 917.28MHz

SPAN 20MHz

OUTPUT SPECTRUM WITH PN SEQUENCE

AT 1.22MHz AT MODIN

MAX2900 toc12

30dBm

-70dBm

10dB/div

MKR

917.35MHz

8.17dBm

CENTER 917.28MHz

SPAN 20MHz

RF OUT RISE AND FALL TIME TRANSIENT

WITH SQUARE OOK

MAX2900 toc13

0dBVp-p

-100dBVp-p

10dB/div

START 46μs

STOP 86μs

RF OUT RISE AND FALL TIME TRANSIENT

WITH SQUARE ASK

MAX2900 toc14

22dBVp-p

-78dBVp-p

10dB/div

START 45μs

STOP 85μs

SPURIOUS LEVEL FROM

DC TO 7TH HARMONIC

MAX2900 toc15

MKR 910MHz

23.17dBm

30dBm

-70dBm

10dB/div

START 0Hz

STOP 7GHz

SPURIOUS LEVEL BETWEEN ±50MHz

FROM CARRIER FREQUENCY

MAX2900 toc16

30dBm

-70dBm

10dB/div

CENTER 917.28MHz

SPAN 100MHz

TRANSMITTER EFFICIENCY vs. R

PWRSET

MAX2900 toc17

PWRSET

(kΩ)

TRANSMITTER EFFICIENCY (%)

383430262218

A B C

E F

A: VCC = 4.5V, TA = -40°C B: V

= 4.5V, TA = +25°C

C: V

= 4.5V, TA = +85°C

D: V

= 2.7V, TA = -40°C

E: V

= 2.7V, TA = +25°C

F: V

= 2.7V, TA = +85°C

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands

8 _______________________________________________________________________________________

Pin Description

MAX2900

MAX2901 MAX2903

MAX2902 MAX2904

NAME PIN TYPE FUNCTION

1 1 1 VTUNE Analog Input VCO tuning voltage input

2 2 2 GND Supply Pin Ground

3 3 3 VREG

Analog

Input/Output

Regulated voltage output to supply the VCO. Bypass with a 0.01µF capacitor to GND as close to the part as possible.

4 4 4 VCC1 Supply Pin

Power supply pin for VCO circuits. Bypass with a 1000pF and a 10µF capacitor to GND as close to the part as possible.

5 5 5 RLPF

Analog Input

Resistor to ground on this pin sets the modulation filter bandwidth.

6 6 6 EN Digital Input

Chip-enable digital input pin. Set EN low maintain the chip in power-down mode.

7 7 7 REFEN Digital Input

Enable for crystal oscillator and frequency reference buffer.

8 8 8 MODIN Digital Input BPSK modulation input

9 9 9 OOKIN Digital Input On-off keying modulation. On state = high.

10 10 10 VCC2 Supply

Power supply pin for internal RF buffer circuits. Bypass with a 100pF and a 0.01µF capacitor to GND as close to the part as possible.

11 11 11 VASK

Analog Voltage

Input

ASK voltage input pin

12 12 — LD

Lock detector output digital pin. Level is high when PLL is inside lock range.

— — 12 D.C.

—

13 13 13 PWRSET

Anal og Inp ut

Current input set to adjust output power.

14 14 14 VCC3 Supply

P ow er sup p l y p i n for RF p ow er am p l i fi er ci r cui ts. Byp ass w i th a 100p F cap aci tor to GN D as cl ose to the p ar t as p ossi b l e.

Resistor to Ground

Digital Output

Do NOT Connect

Resi stor to Gr ound

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for

868MHz/915MHz ISM Bands

_______________________________________________________________________________________ 9

Pin Description (continued)

MAX2900

MAX2901 MAX2903

MAX2902 MAX2904

NAME PIN TYPE FUNCTION

15 15 15 GND Supply Pin Ground

16, 17 16, 17 16, 17 RF-, RF+ RF Output RF d i ffer enti al outp ut, op en- col l ector typ e

18 — — N.C.

—

— 18 — GND Supply Pin Ground

— — 18 D.C.

—

19 — 19 N.C.

—

— 19 — DIVOUT ECL Output Divider output

— 20, 21 20, 21 VCO-, VCO+

Open Collector

VCO output (differential)

20 — — D1 Digital Input Channel selection bit 1

21 — — D0 Digital Input Channel selection bit 0

22 22 22 OSC Analog Input

Crystal oscillator connection. See Typical Operating Circuit.

23 23 23 REFIN

Analog Voltage

Input

Refer ence i np ut p i n anal og ( can b e used as i np ut or as cr ystal osci l l ator d r i ver ) . See Typical Operating Circuit.

24 24 — VCC4 Supply Pin

Power-supply pin for the synthesizer circuits. Bypass with a 1000pF capacitor to GND as close to the part as possible.

— — 24 VCC4 Supply Pin

Power-supply pin for the digital circuits. Bypass with a 100pF capacitor to GND as close to the part as possible.

25 25 25 REFOUT

Buffered clock analog output pin

26 — — D2 Digital Input Channel selection bit 2

— 26 — DIV63 Digital Input

Division ratio selections (division ratio = 62 when DIV63 = high; division ratio = 63 when DIV63 = low).

— — 26 N.C.

—

27 27 — VCC5 Supply Pin

Power-supply pin for charge pump circuits. Bypass with a 100pF capacitor to GND as close to the part as possible.

— — 27 VCC5 Supply Pin

Power-supply pin. Bypass with a 100pF capacitor to GND as close to the part as possible.

28 28 — CPOUT

Charge pump output pin

— — 28 D.C.

—

GROUND GROUND GROUND GROUND

Electrical

Ground

Back side of package is connected to ground.

Not Connected

Do Not Connect

Not Connected

Analog Output

Not Connected

Analog Output

Do Not Connect

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.

• 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.

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.

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.

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; 22kΩ is

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands

10 ______________________________________________________________________________________

1.2V

100Ω

INTERNAL CIRCUITS

PIN PWRSET

EXTERNAL RESISTOR

TO INTERNAL CONTROL CIRCUIT

Figure 1. PIN PWRSET Equivalent Circuit

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for

868MHz/915MHz ISM Bands

______________________________________________________________________________________ 11

used on the EV kit board for +23dBm output power at

4.5V, and 22kΩ is also recommended for +20dBm output power at +3.0V. For +17dBm at 3.0V, 36kΩ 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.

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.

The RLPF pin sets the bandwidth of the modulation filter. The default filter bandwidth, obtained with a 68kΩ resistor, is for 1.2Mchips/s. The bandwidth is increased to accommodate 5Mchips/s by decreasing the resistor value to about 26kΩ. The minimum value for the resistor is 12kΩ, 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.

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.

1.2V

100Ω

INTERNAL CIRCUITS

PIN RLPF

EXTERNAL RESISTOR

TO INTERNAL CONTROL CIRCUIT

Figure 2. PIN VASK Equivalent Circuit

Figure 3. PIN RLPF Equivalent Circuit

TO VREG (2.1V)

TO INTERNAL CONTROL CIRCUIT

>200kΩ

1.5V

INTERNAL CIRCUITS

PIN VASK

EXTERNAL RESISTOR BRIDGE

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands

12 ______________________________________________________________________________________

Table 2. MAX2901/MAX2903 Power-Up Modes

Table 3. MAX2902/MAX2904 Power-Up Modes

Table 4. MAX2900 Synthesizer Programming

REFEN

OOKIN

REFERENCE

VCO MOD FILTER

SYNTHESIZER PA

0 0 X Off Off Off Off

1 0 X On Off Off Off

1 1 0 On On On Off

111 On On On

On only after LD

goes high

Table 5. MAX2901/MAX2903 Synthesizer Programming

DIV 63 DIVISION RATIO

062

163

Table 1. MAX2900 Power-Up Modes

LOGIC LEVEL INTERNAL BLOCK STATUS

REFERENCE

SYNTHESIZER PA

0 0 X Off Off Off Off

1 0 X On Off Off Off

1 1 0 On On On Off

1 1 1 On On On

On only after LD

goes high

REFEN

OOKIN

REFEN EN OOKIN REFERENCE VCO MOD FILTER PA

0 0 X Off Off Off

1 0 0 On Off Off

0 1 0 Off On Off

1 1 0 On On Off

0 1 1 Off On On

111 On On On

VCO MOD FILTER

D0 D1 D2 DIVISION RATIO

0 1 1 249

0 1 0 250

0 0 1 251

0 0 0 252

1 1 1 253

1 1 0 254

1 0 1 255

1 0 0 256

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for

868MHz/915MHz ISM Bands

______________________________________________________________________________________ 13

211920

810911121314

2627 25 24 23 22

REFEN

RLPF

VCC1

VREG

GND

WBFM

(OPT)

VTUNE

GND

R7 R8

ASK

(OPT)

RF-

RF+

N.C.

OSC

REFIN

VCC4

REFOUT

VCC5

CPOUT

VCC3

PWRSET

VASK

VREG

VCC2

OOKIN

OOK

MODIN

MODIN (PN)

VCC_PA

C26

C23

Y1 (OPT)

C25

C24

C15

C16

LOOP

ANTENNA

C31

C33

C28

C18

VCC_DRV

C1 C35

R3 R1

EXT REFERENCE (OPT)

C32

C34

8-CHANNEL

SYNTHESIZER

GATE

REG

÷4

MAX2900

MAX2900 TYPICAL OPERATING CIRCUIT

C12

C13

Typical Operating Circuits

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands

14 ______________________________________________________________________________________

211920

810911121314

2627 25 24 23 22

REFEN

RLPF

C13

VCC1

VREG

GND

WBFM

(OPT)

VTUNE

GND

R7 R8

ASK

(OPT)

RF-

RF+

GND

DIVOUT

VCO-

VCO+

OSC

REFIN

VCC4

REFOUT

R11

VCC5

CPOUT

VCC3

PWRSET

VASK

VREG

VCC2

OOKIN

OOK

MODIN

MODIN (PN)

R10

VCC

C37

VCOOUT

VCC_PA

C26

C23

C25

C24

C15

C16

C12

LOOP

ANTENNA

C31

C33

C28

C18

VCC_DRV

C1 C35

R3 R1

EXT REFERENCE

/FM INPUT

C32

C34

DUAL-

CHANNEL

(/62 OR /63)

SYNTHESIZER

GATE

REG

MAX2901/

MAX2903

MAX2901/MAX2903 TYPICAL OPERATING CIRCUIT

DIV63

Typical Operating Circuits (continued)

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for

868MHz/915MHz ISM Bands

______________________________________________________________________________________ 15

211920

810911121314

2627 25 24 23 22

REFEN

RLPF

C13

VCC1

VREG

GND

WBFM

(OPT)

VTUNE

GND

R7 R8

ASK

(OPT)

RF-

RF+

D.C.

N.C.

VCO-

VCO+

OSC

REFIN

VCC4

REFOUT

R11

N.C.

VCC5

D.C.

VCC3

PWRSET

D.C.

VASK

VREG

VCC2

OOKIN

OOK

MODIN

MODIN (PN)

GATE

REG

MAX2902/

MAX2904

R10

VCC

CPOUT

REFIN

1GHz

FREQUENCY

SYNTH

RFIN

C37

VCOOUT

VCC_PA

C26

C15

C16

C12

LOOP

ANTENNA

C31

C33

C28

C18

VCC_DRV

C1 C35

R3 R1

REFFREQ

/FM

C32

C34

MAX2902/MAX2904 TYPICAL OPERATING CIRCUIT

Typical Operating Circuits (continued)

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands

16 ______________________________________________________________________________________

810911121314

2627 25 24 23 22

REFEN

RLPF

VCC1

VREG

GND

VTUNE

RF-

RF+

D.C.

N.C.

VCO-

VCO+

OSC

REFIN

VCC4

REFOUT

N.C.

VCC5

D.C.

VCC3

PWRSET

D.C.

VASK

VCC2

OOKIN

MODIN

GATE

REG

MAX2902/

MAX2904

GND

Functional Diagrams/

Pin Configurations (continued)

Chip Information

TRANSISTOR COUNT: 898

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for

868MHz/915MHz ISM Bands

______________________________________________________________________________________ 17

32L QFN.EPS

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

200mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands

Package Information (continued)

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information

www.maxim-ic.com/packages

go to

MAX2900–MAX2904

18 ______________________________________________________________________________________

200mW Single-Chip Transmitter ICs for

868MHz/915MHz ISM Bands

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.

Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 19

Revision History

REVISION

NUMBER

REVISION

DATE

DESCRIPTION

PAGES

CHANGED

18/03— —

2 12/07 Separate VCO Tuning Gain specification into two rows 4

MAXIM MAX2900, MAX2904 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual