Datasheet MAX2903EGI Datasheet (Maxim)

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

Functional Diagrams/Pin Configurations

19-2145; Rev 1; 8/03

Ordering Information

*Exposed pad

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

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.

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*

PART TEMP RANGE PIN-PACKAGE

VCC5

GND

CPOUT

28

1

2

3

4

5

6

EN

7

810911121314

MODIN

VTUNE

GND

VREG

VCC1

RLPF

REFEN

VCC5

CPOUT

28

27 25 24 23 22

1

2

3

4

5

6

EN

7

MODIN

MAX2900

CP

REG

GATE

810911121314

OOKIN

D2

26

÷4

VCC2

REFOUT

SYNTHESIZER

VASK

VCC4

8-CHANNEL

LD

REFIN

PWRSET

OSC

VCC3

D0

21

D1

20

19

N.C.

18

N.C.

RF+

17

RF-

16

15

GND

VTUNE

VREG

VCC1

RLPF

REFEN

DIV63

REFOUT

27 25 24 23 22

26

MAX2901/

MAX2903

CP

REG

SYNTHESIZER

GATE

VCC2

OOKIN

VASK

VCC4

DUAL-

CHANNEL

(/62 OR /63)

LD

REFIN

PWRSET

OSC

VCC3

VCO+

21

VCO-

20

19

DIVOUT

18

GND

RF+

17

RF-

16

GND

15

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

CC

+ 0.3V)

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

Continuous Power Dissipation (T

A

= +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

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 Selection Information

CAUTION! ESD SENSITIVE DEVICE

PART FREQUENCY RANGE (MHz) SYNTHESIZER LO OUTPUTS

MAX2900EGI 902 to 928 Internal 8 selectable channels No

MAX2901EGI 902 to 928 Internal 2 selectable channels Yes

MAX2902EGI 902 to 928 Off-chip Yes

MAX2903EGI 867 to 870 Internal 2 selectable channels Yes

MAX2904EGI 867 to 870 Off-chip Yes

Supply Voltage 2.7 4.5 4.5 V

Supply Current

PARAMETER CONDITIONS MIN -3σ TYP +3σ MAX UNITS

Shutdown mode: EN =
REFEN = low

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

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

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

VCC = +4.0V 0.7 10

= +4.5V 60 200

V

CC

32 40

= -40°C

T

A

to +85°C

T

= -40°C

A

to +85°C

150 200

110 135

µA

mA

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)

Supply Current (continued)

VCO Input Tuning Pin Current VTUNE = +4.5V, TA = +25°C 0.02 2 µA

VREG VCO Regulator Voltage 2.0 V

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 10 µA

Output Level High

Output Level Low 0.4 V

Output Current -100 100 µA

ANALOG CONTROL INPUTS (PINS PWRSET, RLPF, VASK)

PWRSET Voltage 1.2 V

RLPF Voltage 1.2 V

VASK Input Impedance 100 220 400 kΩ

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

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

= +25°C75

T

A

T

= +25°C57

A

29 33

V

CC

- 0.5V

V

CC

- 0.4

mA

V

V

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

RF

= 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,

T

A

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

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

RFOUT Frequency Range

REFIN Reference Frequency
Range

REFDIV Fixed Reference Divider
Ratio

Main Divider Ratios

PLL Comparison Frequency

VCO Buffer Output Power 300Ω differential load (MAX2901–MAX2904) -12 d Bm

REFDIV Fixed Reference
Divider Ratio

VCO Phase Noise

VCO Tuning Gain VTUNE = +1.35V 44 65 86 M H z/V

VCO Frequency Pulling with
OOK Modulation

PLL Phase Noise

REFOUT Voltage Swing 100 m V p - p

CPOUT Charge Pump Current 500 µA

Reference Spurs -62 d Bc

Reference Input Voltage for
Nominal Operation

BPSK, OOK MODULATOR, AND PA

MODIN Frequency Range 1.2 8 M b /s

Modulation Filter Nominal 3dB
Bandwidth

Modulation Filter Final Attenuation Measured at 30MHz 28 41 d B

Carrier Suppression 28 d B

Noise Power Density

PARAMETER CONDITIONS MIN -3σ TYP +3σ MAX U N I T S

(MAX2900/MAX2901/MAX2902) 902 917.28 928

(MAX2903/MAX2904) 867 868 870

(MAX2900/MAX2901/MAX2902) 14 14.56 15

(MAX2903/MAX2904) 13 13.78 14.5

(MAX2900) 4 4 4

Table 4 (MAX2900) 249 256

(MAX2901/MAX2903) 62 63

(MAX2900) 3.5 3.64 3.75

(MAX2901/MAX2903) 13 15

(MAX2901/MAX2903) 1 1 1

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

OOKIN clocked at 19kHz, internal (crystal)
or external reference frequency 60 kH z p eak

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

Using an external frequency reference 200 300 m V

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

-101 d Bc/H z

5kH z RM S

-96 d Bc/H z

1M H z

-150 d Bc/H z

M H z

M H z

M H z

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

RF

= 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,

T

A

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

RF Output Power

RF Output Power Flatness

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

ASK Output Power Adjustment
Range

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

Spurious Emissions

PARAMETER CONDITIONS MIN -3σ TYP +3σ MAX U N I T S

PWRSET = 22kΩ, VCC = +4.5V,

= +25°C

T

A

PWRSET = 22kΩ, VCC = +4.5V,

= -40°C to +85°C

T

A

P WRS E T = 22kΩ , V

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

f

= 867MHz to 870MHz

RF

ASK output power back­off relative to max power

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)

C C

= + 3.0V , TA = + 25°C 18 20 21

21 23.5 25

20.5 25

0.3

0.1

OOKIN = high,
VASK = 0

OOKIN = high,
VASK = 1V

41

16

-50

-51

-63

< -70

d Bm

d B

d B

d Bc

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

Unlocked, Out-of-Band Spurious
Output Level

Noise Level Out of Band

Output VSWR for Guaranteed
Stability

M axi m um Al l ow ab l e Outp ut V S WR 2:1

Any condition when synthesizer unlocked
(pin LD low)

Modulation off, measured at 960MHz, any
gain setting (MAX2900/MAX2901/MAX2902)

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

< -70

< -50 d Bm

-126 -120

d Bm /H z

-126 -120

2:1

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

CC

= 4.5V, TA= +25°C, unless

otherwise noted.)

SUPPLY CURRENT vs. V

CC

MAX2900 toc01

VCC (V)

SUPPLY CURRENT (mA)

4.03.53.0

90

100

110

120

130

140

150

160

80

2.5 4.5

TA = +85°C

TA = +25°C

TA = -40°C

SHUTDOWN CURRENT vs. V

CC

MAX2900 toc02

VCC (V)

SHUTDOWN CURRENT (µA)

4.03.53.0

1

10

100

0.1

2.5 4.5

TA = +85°C

TA = +25°C

TA = -40°C

OUTPUT POWER vs. V

CC

MAX2900 toc03

VCC (V)

OUTPUT POWER (dBm)

4.03.53.0

18

20

22

24

26

16

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

CC

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

R

RLPF

(kΩ)

LOWPASS FILTER 3-dB BANDWIDTH (kHz)

6050403020

500

1000

1500

2000

2500

3000

3500

0

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

19

20

21

22

23

24

25

18

900 930

A
B

C

E

F

D

A: VCC = 4.5V, TA = -40°C
B: V

CC

= 4.5V, TA = +25°C

C: V

CC

= 4.5V, TA = +85°C

D: V

CC

= 2.7V, TA = -40°C

E: V

CC

= 2.7V, TA = +25°C

F: V

CC

= 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

CC

= 4.5V, TA= +25°C, unless

otherwise noted.)

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for

868MHz/915MHz ISM Bands

_______________________________________________________________________________________ 7

17

16

15

14

RF POWER (dBm)

13

12

860 876

RF OUT RISE AND FALL TIME TRANSIENT

0dBVp-p

RF POWER vs. FREQUENCY

(MAX2903/MAX2904)

RF OUTPUT MATCHING
OPTIMIZED FOR +14dBm
OUTPUT AT V

= +3.0V

CC

FREQUENCY (MHz)

WITH SQUARE OOK

T

r

VCC = +3.6V

VCC = +3.0V

VCC = +2.7V

872868864

T

f

OUTPUT SPECTRUM WITH 600kHz

SQUARE WAVE INPUT AT MODIN

30dBm

MKR

917.31MHz

-70dBm

-16.33dBm

CENTER 917.28MHz

SPAN 20MHz

MAX2900 toc10

10dB/div

RF OUT RISE AND FALL TIME TRANSIENT

WITH SQUARE ASK

22dBVp-p

MAX2900 toc13

T

r

T

f

MAX2900 toc11

10dB/div

-70dBm

MAX2900 toc14

OUTPUT SPECTRUM WITH PN SEQUENCE

AT 1.22MHz AT MODIN

30dBm

MKR

917.35MHz

8.17dBm

CENTER 917.28MHz

SPURIOUS LEVEL FROM

DC TO 7TH HARMONIC

30dBm

SPAN 20MHz

MKR
910MHz

23.17dBm

MAX2900 toc12

MAX2900 toc15

10dB/div

-100dBVp-p
START 46µs

30dBm

10dB/div

-70dBm

10dB/div

STOP 86µs

-78dBVp-p
START 45µs

SPURIOUS LEVEL BETWEEN ±50MHz

FROM CARRIER FREQUENCY

CENTER 917.28MHz

SPAN 100MHz

MAX2900 toc16

10dB/div

-70dBm

STOP 85µs

START 0Hz

TRANSMITTER EFFICIENCY vs. R

45

A

40

B
C

D

35

E

F

30

25

A: VCC = 4.5V, TA = -40°C

= 4.5V, TA = +25°C

B: V

CC

20

TRANSMITTER EFFICIENCY (%)

15

10

C: V

CC

D: V

CC

E: V

CC

F: V

CC

14

= 4.5V, TA = +85°C

= 2.7V, TA = -40°C
= 2.7V, TA = +25°C
= 2.7V, TA = +85°C

R

PWRSET

STOP 7GHz

PWRSET

MAX2900 toc17

383430262218

(kΩ)

MAX2900–MAX2904

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

8 _______________________________________________________________________________________

Pin Description

PIN

MAX2900

1 1 1 VTUNE Analog Input VCO tuning voltage input

2 2 2 GND Supply Pin Ground

3 3 3 VREG

4 4 4 VCC1 Supply Pin

5 5 5 RLPF

6 6 6 EN Digital Input

7 7 7 REFEN Digital Input

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

MAX2901
MAX2903

MAX2902
MAX2904

NAME PIN TYPE FUNCTION

Analog

Input/Output

Analog Input

Resistor to Ground

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

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

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

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

Enable for crystal oscillator and frequency
reference buffer.

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

12 12 — LD Digital Output

——12 D.C. Do NOT Connect —

13 13 13 PWRSET

14 14 14 VCC3 Supply

Analog Voltage

Input

Anal og Inp ut

Resi stor to Gr ound

ASK voltage input pin

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

Current input set to adjust output power.

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.

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for

868MHz/915MHz ISM Bands

_______________________________________________________________________________________ 9

Pin Description (continued)

PIN

MAX2900

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. Not Connected —

— 18 — GND Supply Pin Ground

——18 D.C. Do Not Connect —

19 — 19 N.C. Not Connected —

— 19 — DIVOUT ECL Output Divider output

— 20, 21 20, 21 VCO-, VCO+

20 —— D1 Digital Input Channel selection bit 1

21 —— D0 Digital Input Channel selection bit 0

22 22 22 OSC Analog Input

23 23 23 REFIN

24 24 — VCC4 Supply Pin

MAX2901
MAX2903

MAX2902
MAX2904

NAME PIN TYPE FUNCTION

Open Collector

Analog Voltage

RF

Input

VCO output (differential)

Crystal oscillator connection. See Typical
Operating Circuit.

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.

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.

——24 VCC4 Supply Pin

25 25 25 REFOUT Analog Output Buffered clock analog output pin

26 —— D2 Digital Input Channel selection bit 2

— 26 — DIV63 Digital Input

——26 N.C. Not Connected —

27 27 — VCC5 Supply Pin

——27 VCC5 Supply Pin

28 28 — CPOUT Analog Output Charge pump output pin

——28 D.C. Do Not Connect —

GROUND GROUND GROUND GROUND

Electrical

Ground

Bypass with a 100pF capacitor to GND as
close to the part as possible.

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.

Back side of package is connected to
ground.

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 ______________________________________________________________________________________

Figure 1. PIN PWRSET Equivalent Circuit

TO INTERNAL
CONTROL
CIRCUIT

100Ω

1.2V

INTERNAL
CIRCUITS

PIN PWRSET

EXTERNAL
RESISTOR

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.

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

TO INTERNAL
CONTROL
CIRCUIT

1.2V

100Ω

INTERNAL
CIRCUITS

PIN RLPF

EXTERNAL
RESISTOR

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

Table 5. MAX2901/MAX2903 Synthesizer
Programming

DIV 63 DIVISION RATIO

062

163

Table 1. MAX2900 Power-Up Modes

REFEN EN OOKIN REFERENCE VCO MOD FILTER SYNTHESIZER PA

REFEN EN OOKIN REFERENCE VCO MOD FILTER SYNTHESIZER PA

REFEN EN OOKIN REFERENCE VCO MOD FILTER PA

LOGIC LEVEL INTERNAL BLOCK STATUS

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

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

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

On only after LD

goes high

On only after LD

goes high

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

Typical Operating Circuits

EXT REFERENCE (OPT)

C25

Y1 (OPT)

C23

C26

REFOUT

C28

C24

OSC

REFIN

VCC4

REFOUT

D2

VCC5

CPOUT

LOOP

ANTENNA

L5

C33

C34

RF+

L4

C16

C32

L1

GND

RF-

17

16

15

GATE

5

6

7

L2

810911121314

VCC_PA

C12

VCC3

LD

VASK

VCC2

OOKIN

MODIN

VCC_DRV

PWRSET

ASK

VREG

R6

C18

(OPT)

R7 R8

C8

MAX2900 TYPICAL OPERATING CIRCUIT

L3

C15

D0

D1

D1

D0

211920

2627 25 24 23 22

N.C.

÷4

C31

N.C.

18

8-CHANNEL

SYNTHESIZER

MAX2900

CP

28

2

1

REG

3

4

(OPT)

WBFM

GND

VTUNE

C1 C35

R3 R1

R4

C2

VREG

C3

RLPF

C13

EN

REFEN

R5

OOK

MODIN (PN)

VCC1

C4

MAX2900–MAX2904

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

14 ______________________________________________________________________________________

Typical Operating Circuits (continued)

LOOP

ANTENNA

L5

C33

C34

VCOOUT

C37

R10

VCC

L4

C16

VCC_PA

EXT REFERENCE

/FM INPUT

C15

L3

OSC

REFIN

VCC4

REFOUT

DIV63

2627 25 24 23 22

VCC5

28

CPOUT

R11

VCO+

211920

1

VTUNE

C1 C35

C25

Y1

C23

C24

C26

REFOUT

C28

VCO-

MAX2903

MAX2901/

2

GND

CP

DIVOUT

3

VREG

GND

DUAL-

CHANNEL

REG

VCC1

C4

C31

18

(/62 OR /63)

SYNTHESIZER

4

C13

L1

RF+

RLPF

C32

L2

GND

RF-

17

16

15

GATE

5

6

7

EN

REFEN

R5

C12

VCC_DRV

VCC3

PWRSET

LD

VREG

VASK

VCC2

OOKIN

810911121314

MODIN

OOK

MODIN (PN)

R6

ASK

C18

(OPT)

R7 R8

C8

MAX2901/MAX2903 TYPICAL OPERATING CIRCUIT

(OPT)

WBFM

R3 R1

C2

C3

R4

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for

868MHz/915MHz ISM Bands

______________________________________________________________________________________ 15

Typical Operating Circuits (continued)

REFFREQ

/FM

REFIN

CPOUT

C26

C28

1GHz

VCC

SYNTH

FREQUENCY

R10

R11

OSC

REFIN

VCC4

REFOUT

2627 25 24 23 22

N.C.

VCC5

28

D.C.

C37

VCO+

211920

1

RFIN

VCOOUT

VCO-

2

C15

N.C.

3

LOOP

ANTENNA

L5

C33

C34

RF+

L4

C16

C32

L1

GND

RF-

17

16

15

GATE

5

6

7

L2

810911121314

VCC_PA

C12

VCC3

D.C.

VASK

VCC2

OOKIN

MODIN

VCC_DRV

PWRSET

ASK

VREG

R6

C18

(OPT)

R7 R8

C8

MAX2902/MAX2904 TYPICAL OPERATING CIRCUIT

L3

C31

D.C.

18

MAX2904

MAX2902/

REG

4

(OPT)

WBFM

GND

VTUNE

C1 C35

R3 R1

R4

C2

VREG

C4

C3

VCC1

C13

RLPF

EN

REFEN

R5

OOK

MODIN (PN)

MAX2900–MAX2904

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

16 ______________________________________________________________________________________

Functional Diagrams/

Pin Configurations (continued)

Chip Information

TRANSISTOR COUNT: 898

VTUNE

1

D.C.

28

VCC5

REFOUT

N.C.

2627 25 24 23 22

VCC4

REFIN

OSC

VCO+

21

2

GND

3

VREG

VCC1

4

REG

MAX2902/

MAX2904

RLPF

5

6

EN

7

REFEN

GATE

810911121314

MODIN

OOKIN

VCC2

VASK

D.C.

PWRSET

VCC3

VCO-

20

19

N.C.

18

D.C.

RF+

17

RF-

16

GND

15

MAX2900–MAX2904

200mW Single-Chip Transmitter ICs for

868MHz/915MHz ISM Bands

______________________________________________________________________________________ 17

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

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.

18 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

© 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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

.)