MAXIM MAX9947 Technical data

19-5029; Rev 3; 7/11

Functional Diagram

EVALUATION KIT

AVAILABLE

AISG Integrated Transceiver

General Description

The MAX9947 is an AISG-compliant, fully integrated
transceiver.

The MAX9947 receiver offers a typical dynamic range of
20dB and integrates a bandpass filter that operates in the

2.176MHz frequency with a narrow 200kHz bandwidth.

The MAX9947 transmitter integrates a bandpass filter
that is compliant with the AISG spectrum emission pro­file. It can modulate OOK signals up to 115.2kbps. The
output power can be varied with external resistors from
+7dBm to +12dBm to compensate for loss in the external
circuitry and cabling.

The MAX9947 also features a direction output to facilitate
the RS-485 bus arbitration in tower-mounted equipment.

The MAX9947 is available in a small, 3mm x 3mm 16-pin
TQFN and is rated for operation in the -40°C to +85°C
temperature range.

Applications

Base Stations

Tower Equipment

Features

S Receiver Wide Input Dynamic Range

-15dBm to +5dBm in 50I

S Variable Transmitter Output Level from +7dBm to

+12dBm

S AISG-Compliant Output Emission Profile
S AutoDirection Output
S No Need of Microcontrollers to Handle Bus

Arbitration in Tower-Mounted Equipment

S Supports All AISG Data Rates

9.6kbps

38.4kbps

115.2kbps

S Bandpass Filter Compliant with AISG Protocol

Centered Around 2.176MHz

S 3.0V to 5.5V Voltage Supply
S Independent Logic Supply
S Small, 3mm x 3mm 16-Pin TQFN Package

Ordering Information

PART

MAX9947ETE+

+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad. Connect EP to GND to enhance thermal

dissipation.

TEMP

RANGE

-40NC to
+85NC

PIN-PACKAGE

16 TQFN-EP* AHF

TOP

MARK

MAX9947

V

L

V

CC

XTAL1

XTAL2

TXIN

DIRMD1
DIRMD2

DIR

RXOUT

GND

_______________________________________________________________ Maxim Integrated Products 1

DIRECTION
DETECTION

STATE MACHINE

ANALOG
SWITCH

RES BIAS

+7dBm TO +12dBm

REF

-15dBm

OOK

DEMODULATOR

1.5V

TXOUT

BANDPASS FILTER

SYNCOUT

MAX9947

RXIN

BANDPASS FILTER

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.

AISG Integrated Transceiver

ABSOLUTE MAXIMUM RATINGS

VCC to GND .............................................................-0.3V to +6V

VL to GND ...............................................................-0.3V to +6V

TXOUT, BIAS to GND ............................... -0.3V to (VCC + 0.3V)

RXIN, XTAL1, XTAL2, SYNCOUT, RES to GND ......-0.3V to +6V

TXIN, RXOUT, DIR, DIRMD1,

DIRMD2 to GND ...................................... -0.3V to (VL + 0.3V)

Output Short-Circuit Current TXOUT,

SYNCOUT to VCC or GND ....................................Continuous

MAX9947

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.

PACKAGE THERMAL CHARACTERISTICS (Note 1)

TQFN

Junction-to-Ambient Thermal Resistance (qJA) .......57.2°C/W

Junction-to-Case Thermal Resistance (qJC) ...............40°C/W

Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-

layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.

ELECTRICAL CHARACTERISTICS

(VCC = 5V, VL = 3.3V, TXOUT connected with 50I to RXIN, 4.1kI resistor between BIAS and RES, 10kI resistor between RES and
GND, 1kI resistor between SYNCOUT and VCC, TA = T
Typical values are at TA = +25°C.) (Note 2)

PARAMETER SYMBOL CONDITION MIN TYP MAX UNITS

DC CHARACTERISTICS

Supply Voltage V
Supply Current I
Logic Supply Voltage V
Logic Supply Current I

Receiver Power-Supply
Rejection Ratio

Output Power-Supply
Rejection Ratio

LOGIC INPUTS AND OUTPUTS

Logic-Input High Threshold
Voltage

Logic-Input Low Threshold
Voltage

Logic-Output High Threshold
Voltage

Logic-Output Low Threshold
Voltage

Input Leakage Current IIH, I

SYNC INPUT (XTAL1) AND OUTPUT (SYNCOUT)

Input High Threshold Voltage V

CC

CC

L

PSRR

V

IH

V

IL

V

OH

V

OL

XTAL1_IH

Guaranteed by PSRR 3.0 5.5 V

Guaranteed by logic supply current 1.6 5.5 V

L

V

TXIN

3.0V P VCC P 5.5V, V
(Note 3)

3.0V P VCC P 5.5V, V
(Note 4)

DIRMD1, DIRMD2, TXIN 0.7 x V

DIRMD1, DIRMD2, TXIN 0.3 x V

RXOUT, DIR source 3.3mA 0.9 x V

RXOUT, DIR sink 3.3mA 0.1 x V

TXIN shorted to GND or V

IL

DIRMD1, DIRMD2

to T

MIN

= 3.3V 138 380

All Other Pins Max In/Out Current ................................... ±20mA

Continuous Power Dissipation (TA = +70°C)

16-Pin TQFN (derate 17.5mW/°C) .............................1399mW

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

Soldering Temperature (reflow) ......................................+260°C

, unless otherwise specified. XTAL frequency 8.704MHz ±30ppm.

MAX

23 35 mA

= 3.3V

TXIN

= 0V

TXIN

L

Shorted to GND +60
Shorted to V

L

49 60 dB

49 60 dB

L

L

L

L

Q1

-1

0.7 x
V

CC

FA

V

V

V

V

FA

V

2 ______________________________________________________________________________________

AISG Integrated Transceiver

ELECTRICAL CHARACTERISTICS (continued)

(VCC = 5V, VL = 3.3V, TXOUT connected with 50I to RXIN, 4.1kI resistor between BIAS and RES, 10kI resistor between RES and
GND, 1kI resistor between SYNCOUT and VCC, TA = T
Typical values are at TA = +25°C.) (Note 2)

PARAMETER SYMBOL CONDITION MIN TYP MAX UNITS

Input Low Threshold Voltage V

Input High Leakage Current I
Input Low Leakage Current I
Output Low Voltage V

XTAL1_IL

XTAL1_IH

XTAL1_IL

SYNCOUT_OL

SYNCOUT source 3.3mA 0.4 V

RECEIVER FILTER

Passband f

Extra Carrier Receiver Immunity
Level 1

PB_L

f

IM1_L

, f

, f

Input amplitude 1.12V

PB_H

(the input carrier is recognized)

2.176MHz carrier amplitude (112.4mV
Q3dB), extra carrier amplitude 0.8V

IM1_H

V

DIRMD1

2.176MHz carrier amplitude (112.4mV
Extra Carrier Receiver Immunity
Level 2

f

IM2_L

, f

Q3dB), extra carrier amplitude 0.8V

IM2_H

V

DIRMD1

V

DIRMD1

RECEIVER

Input Voltage Range V
Equivalent Input Power Range P
Input Impedance Z

Threshold Voltage Range V

IN

IN

IN

TH

VCC = 3.0V to 5.5V, f
VCC = 3.0V to 5.5V, f
f = f

f

RXIN

TRANSMITTER

Output Frequency f
Output Frequency Variation

Output On Level at TXOUT
(Note 6)

Output Off Power Level at
TXOUT (Note 6)

V

P

O

Df

OUT

OUT

(Note 5)

O

V

RES

V

RES

OOK off level -40 dBm

f = fO Q200kHz
f = fO Q500kHz

Output Emission Profile

10MHz P f P 25MHz
25MHz P f (Note 7)
f P 1MHz

Output Impedance Z

OUT

DC 0.03
f = 10MHz 2.5

Amplifier Gain Bandwidth GBW 54 MHz

TXOUT Short-Circuit Protection I

SC

Short to GND or VCC, guaranteed over VCC
range

MIN

O

to T

= V

= 3.3V, V
= 0V, V

, unless otherwise specified. XTAL frequency 8.704MHz ±30ppm.

MAX

DIRMD2

DIRMD2

DIRMD2

= 2.176MHz

= 1.5V (maximum)

= 0.7V (minimum)

0.3 x
V

CC

10

-10

P-P

P-P

P-P

,

1.1 4.17 MHz

1.1 4.17 MHz

= 0V (9.6kbps)

P-P

,

P-P

= 0V (38.4kbps),

4.17 MHz

= 3.3V (115.2kbps)

= 2.176MHz 1.12 V

RXIN

= 2.176MHz +5 dBm

RXIN

11 27

-18 -15 -12 dBm

79.72 112.4 158.48 mV

2.176 MHz
Q100

11.1 12 dBm

2.24 2.52 V

5.38 6.28 dBm

1.30 1.17 V

-10

-30

-41

-72

-41

Q200

V

FA
FA

P-P

kI

P-P

ppm

P-P

P-P

dB

I

mA

MAX9947

_______________________________________________________________________________________ 3

AISG Integrated Transceiver

ELECTRICAL CHARACTERISTICS (continued)

(VCC = 5V, VL = 3.3V, TXOUT connected with 50I to RXIN, 4.1kI resistor between BIAS and RES, 10kI resistor between RES and
GND, 1kI resistor between SYNCOUT and VCC, TA = T
Typical values are at TA = +25°C.) (Note 2)

PARAMETER SYMBOL CONDITION MIN TYP MAX UNITS

SWITCHING CHARACTERISTICS

MAX9947

Receiver Propagation Delay t

Receiver Output Rise and
Fall Time

Transmitter Propagation Delay t
DIR to RXOUT Delay (Note 8) t

Direction Duration High t

Receiver Output Data
Duty-Cycle Variation

RX

tR, t

F

TX

DIR, SKEW

DIR, HIGH

DDC

RXIN to RXOUT, V

RXIN to RXOUT, V
V

DIRMD2

V

DIRMD2

10% to 90%, RL = 1kI, CL = 10pF

TXIN to TXOUT 5

V

DIRMD1

V

DIRMD1

V

DIRMD1

RXIN fed by an OOK

2.176MHz sinusoidal
signal with 50% duty
cycle (Note 9)

to T

MIN

= 0V (38.4kbps), V
= 3.3V (115.2kbps)

= V
= 3.3V, V
= 0V, V

, unless otherwise specified. XTAL frequency 8.704MHz ±30ppm.

MAX

DIRMD1

DIRMD1

= 0V (9.6kbps) 1667

DIRMD2

DIRMD2

DIRMD2

= V

= 3.3V,

DIRMD1

= 0V (38.4kbps) 417

= 3.3V (115.2kbps) 137

RXIN = 0dBm -7.5

RXIN = -10dBm +2

= 0V 8.9 11

DIRMD2

= 0V,

270 ns

5.5 11

20 ns

Q10

Q10

Fs

Fs

Fs

%

Note 2: All devices are 100% production tested at TA = +25°C. Specification over temperature limits are guaranteed by design.
Note 3: Defined as DV
Note 4. Defined as DV
Note 5: Guaranteed by design.
Note 6: See the Transmission Output Power section for external resistor values.
Note 7: Guaranteed by design with a recommended 470pF capacitor between RXIN and ground. Measurements above 150MHz

are determined by setup.

Note 8: See Figure 1.
Note 9: Q2µs envelope rise/fall.

/DVCC at DC.

RXIN

/DVCC at DC.

TXOUT

4 ______________________________________________________________________________________

AISG Integrated Transceiver

Typical Operating Characteristics

(VCC = 5V, VL = 3.3V, TXOUT connected with 50I to RXIN, RXIN connected to 50I in series with 220nF to GND, R1 = 10kI between
BIAS and RES, R2 = ∞, pullup SYNCOUT with 1kI to VL, TA = T

MIN

to T

, unless otherwise specified.)

MAX

MAX9947

QUIESCENT CURRENT
vs. SUPPLY VOLTAGE

25

TXIN = V

L

23

21

19

QUIESCENT CURRENT (mA)

17

15

3.0 5.5
SUPPLY VOLTAGE (V)

MAXIMUM TRANSMITTER OUTPUT

LEVEL vs. SUPPLY VOLTAGE

14

12

10

8

6

4

TRANSMITTER OUTPUT (dBm)

2

QUIESCENT CURRENT

30

TXIN = V

L

MAX9947 toc01

27

24

VCC = 5.0V

21

QUIESCENT CURRENT (mA)

18

5.04.54.03.5

15

-40 85
TEMPERATURE (°C)

VCC = 3.0V

603510-15

MAX9947 toc02

TRANSMITTER OUTPUT (dBm)

MAXIMUM TRANSMITTER OUTPUT

LEVEL vs. TEMPERATURE

14

vs. TEMPERATURE

MAX9947 toc04

13

12

11

TRANSMITTER OUTPUT (dBm)

VCC = 5.0V

VCC = 3.0V

MAX9947 toc05

TRANSMITTER OUTPUT (dBm)

TRANSMITTER OUTPUT vs. V

14

12

10

8

6

4

2

0

0.7 1.5
V

RES

1.31.10.9

(V)

TRANSMITTER OUPUT SPECTRUM

vs. FREQUENCY (9.6kbps)

20

0

-20

-40

-60

-80

-100

90% DUTY CYCLE
C

= 470pF

F

RES

MAX9947 toc03

MAX9947 toc06

0

3.0 5.5
SUPPLY VOLTAGE (V)

TRANSMITTER OUPUT SPECTRUM

vs. FREQUENCY (9.6kbps)

20

0

-20

-40

-60

-80

TRANSMITTER OUTPUT (dBm)

-100

-120
0 25

90% DUTY CYCLE
CF = 470pF

FREQUENCY (MHz)

_______________________________________________________________________________________ 5

5.04.54.03.5

10

-40 85
TEMPERATURE (°C)

603510-15

TRANSMITTER OUPUT SPECTRUM

vs. FREQUENCY (38.4kbps)

20

0

MAX9947 toc07

-20

-40

-60

-80

TRANSMITTER OUTPUT (dBm)

-100

2015105

-120

0.1 1000

90% DUTY CYCLE
C

= 470pF

F

FREQUENCY (MHz)

100101

-120

0.1 1000

TRANSMITTER OUPUT SPECTRUM

20

MAX9947 toc08

0

-20

-40

-60

-80

TRANSMITTER OUTPUT (dBm)

-100

-120
0 25

100101

FREQUENCY (MHz)

vs. FREQUENCY (38.4kbps)

90% DUTY CYCLE
CF = 470pF

2015105

FREQUENCY (MHz)

MAX9947 toc09

AISG Integrated Transceiver

Typical Operating Characteristics (continued)

(VCC = 5V, VL = 3.3V, TXOUT connected with 50I to RXIN, RXIN connected to 50I in series with 220nF to GND, R1 = 10kI between
BIAS and RES, R2 = ∞, pullup SYNCOUT with 1kI to VL, TA = T

MIN

to T

, unless otherwise specified.)

MAX

TRANSMITTER OUPUT SPECTRUM

vs. FREQUENCY (115.2kbps)

20

MAX9947

0

-20

-40

-60

-80

TRANSMITTER OUTPUT (dBm)

-100

-120

0.1 1000
FREQUENCY (MHz)

0

-10

-20

-30

-40

PSRR (dB)

-50

-60

-70

-80

0

TRANSMITTER OUPUT SPECTRUM

90% DUTY CYCLE
C

= 470pF

F

100101

20

MAX9947 toc10

0

-20

-40

-60

-80

TRANSMITTER OUTPUT (dBm)

-100

-120
0 25

POWER-SUPPLY REJECTION RATIO

vs. FREQUENCY

TXIN = V

L

0.01 100,000
FREQUENCY (kHz)

10,00010000.1 1 10 100

RECEIVER INPUT THRESHOLD

vs. TEMPERATURE

vs. FREQUENCY (115.2kbps)

90% DUTY CYCLE
C

= 470pF

F

2015105

FREQUENCY (MHz)

20

18

MAX9947 toc13

16

14

12

10

RECEIVER INTPUT IMPEDANCE (kI)

400

TRANSMITTER OUPUT IMPEDANCE

vs. FREQUENCY

25

MAX9947 toc11

20

15

10

5

TRANSMITTER OUTPUT IMPEDANCE (I)

0

0.01 100
FREQUENCY (MHz)

RECEIVER INPUT IMPEDANCE

vs. FREQUENCY

8

6

4

2

0

0.1 10,000
FREQUENCY (kHz)

1000100101

DIR TO RECEIVER OUTPUT DELAY

vs. TEMPERATURE

MAX9947 toc12

1010.1

MAX9947 toc14

-4

-8

-12

-16

RECEIVER INPUT THRESHOLD (dBm)

-20

-40 85

RXOUT = STABLE LOW

RXOUT = STABLE HIGH

TEMPERATURE (°C)

603510-15

MAX9947 toc15

380

360

340

320

DIR TO RECEIVER OUTPUT DELAY (ns)

300

-40 85
TEMPERATURE (°C)

603510-15

6 ______________________________________________________________________________________

MAX9947 toc16

AISG Integrated Transceiver

Typical Operating Characteristics (continued)

(VCC = 5V, VL = 3.3V, TXOUT connected with 50I to RXIN, RXIN connected to 50I in series with 220nF to GND, R1 = 10kI between
BIAS and RES, R2 = ∞, pullup SYNCOUT with 1kI to VL, TA = T

MIN

to T

, unless otherwise specified.)

MAX

MAX9947

TRANSMITTER PROPAGATION DELAY

AT 9.6kbps

20µs/div

MAX9947 toc17

RECEIVER PROPAGATION DELAY

AT 9.6kbps

MAX9947 toc19

TXIN
2V/div

TXOUT
1V/div

RXIN
500mV/div

RXOUT
2V/div

TRANSMITTER PROPAGATION DELAY

AT 115.2kbps

2µs/div

MAX9947 toc18

RECEIVER PROPAGATION DELAY

AT 115.2kbps

MAX9947 toc20

TXIN
2V/div

TXOUT
1V/div

RXIN
500mV/div

RXOUT
2V/div

20µs/div

RECEIVER OUTPUT TO DIR

AT 9.6kbps

V

= V

DIRMD1

DIRMD2

400µs/div

RECEIVER OUTPUT TO DIR

MAX9947 toc21

= 0V

RXOUT
2V/div

DIR
2V/div

2µs/div

AT 38.4kbps

V

= VL, V

DIRMD1

100µs/div

MAX9947 toc22

DIRMD2

= 0V

RXOUT
2V/div

DIR
2V/div

_______________________________________________________________________________________ 7

AISG Integrated Transceiver

Typical Operating Characteristics (continued)

(VCC = 5V, VL = 3.3V, TXOUT connected with 50I to RXIN, RXIN connected to 50I in series with 220nF to GND, R1 = 10kI between
BIAS and RES, R2 = ∞, pullup SYNCOUT with 1kI to VL, TA = T

RECEIVER OUTPUT TO DIR

AT 115.2kbps

V

DIRMD1

= 0V, V

MAX9947 toc23

DIRMD2

= V

L

MAX9947

RXOUT
2V/div

MIN

to T

, unless otherwise specified.)

MAX

DIR TO RECEIVER OUTPUT

MAX9947 toc24

RXOUT
2V/div

40µs/div

RECEIVER OUTPUT DUTY CYCLE

vs. RECEIVER INPUT (9.6kbps)

60

56

52

48

44

RECEIVER OUTPUT DUTY CYCLE (%)

40

-10 5
RECEIVER INPUT (dBm)

DIR
2V/div

100ns/div

DIR
2V/div

RECEIVER OUTPUT DUTY CYCLE

vs. RECEIVER INPUT (115.2kbps)

60

MAX9947 toc25

2-1-4-7

50

40

30

20

10

RECEIVER OUTPUT DUTY CYCLE (%)

0

-10 4
RECEIVER INPUT (dBm)

MAX9947 toc26

20-2-4-6-8

RECEIVER OUTPUT DUTY CYCLE

(9.6kbps)

MAX9947 toc27

RXIN = 3dBm

RXIN
500mV/div

RXOUT
1V/div

100µs/div

8 ______________________________________________________________________________________

AISG Integrated Transceiver

Pin Configuration

TOP VIEW

BIAS

V

XTAL1

XTAL2

GND

RXIN

TXOUT

12 11 9

13

CC

14

15

16

MAX9947

+

RES

10

GND

8

DIRMD1

7

DIRMD2

6

DIR

EP*

5

MAX9947

1 2

TXIN

SYNCOUT

THIN QFN

(3mm x 3mm)

*EP = EXPOSED PAD. CONNECT EP TO GND TO ENHANCE THERMAL DISSIPATION.

4

3

L

V

RXOUT

Pin Description

PIN NAME FUNCTION

1 SYNCOUT Sync Output. Open-drain output that outputs the 8.704MHz clock to synchronize other devices.
2 TXIN Digital Signal Input
3 V
4 RXOUT Digital Signal Output
5 DIR Direction Output. DIR is asserted high when the data stream is seen at the receiver (RXIN).
6 DIRMD2 Duration Mode Select Input 2
7 DIRMD1 Duration Mode Select Input 1

8, 16 GND Ground

9 RES External Resistors’ Connection to Set the Output Power Level
10 BIAS
11 RXIN OOK-Modulated Input Signal
12 TXOUT OOK-Modulated Output Signal
13 V

CC

14 XTAL1
15 XTAL2 External Crystal Input Terminal. Connect to GND for external synchronization.

— EP Exposed Pad. Connect EP to GND to enhance thermal dissipation.

Logic Supply Voltage

L

Output Bias Reference. Used with RES to set the output power level. Decouple BIAS with 1FF to GND.

Analog Supply Voltage
External Crystal Input Terminal. Feed with 8.704MHz (Q30ppm) input clock for external synchronization.

_______________________________________________________________________________________ 9

AISG Integrated Transceiver

Detailed Description

The MAX9947 is an AISG-compliant, fully integrated
transceiver.

The MAX9947 transmitter includes an OOK modulator, a
bandpass filter that is compliant with the AISG spectrum
emission profile, and an output amplifier. The output
power can be varied with external resistors from +7dBm
to +12dBm (+1dBm to +6dBm at the feeder cable) to

MAX9947

compensate for loss in the external circuitry and cabling.
The OOK carrier is generated by applying an external
crystal at 8.704MHz to the OOK internal modulator
through the XTAL1 and XTAL2 pins. An external clock
source at the same frequency can also be applied to
XTAL1 by connecting XTAL2 to ground.

The MAX9947 receiver includes a narrow 200kHz band­width bandpass filter that operates around the 2.176MHz
center frequency. It also includes an OOK demodulator
and a comparator that reconstruct the digital signal. The
minimum sensitivity of the receiver is -15dBm (typ) in
compliance with the AISG standard specifications.

The MAX9947 also features a direction output to facilitate
the RS-485 bus arbitration in tower-mounted equipment.

Direction Output

The MAX9947 provides a direction output pin (DIR) that
indicates the direction of the data flow. This feature is
very useful in the tower that acts as a slave in the AISG

protocol. The base is the master and it controls the flow of
the data by performing the bus arbitration. The output DIR
allows the equipment in the tower to avoid any involvement
in the bus arbitration. See the Typical Application Circuit
(Connectivity at the Tower) that shows how the MAX9947
can be used in the tower in conjunction with the RS-485
transceiver such as the MAX13485E or MAX13486E.

The output DIR drives the DE (driver output enable) and
RE_ (receiver output enable) of the RS-485 transceiver.

Whenever the data flows from RXIN to RXOUT, the out­put DIR is asserted high. When the MAX9947 is located
in the tower, the data flow is being sent from the base
(master) to the tower (slave). On the other side, when the
data flows in the opposite direction, from TXIN to TXOUT
the output DIR is asserted low. However, the MAX9947
internal state machine is sensing both the TXIN and RXIN
lines, and can recognize the correct flow of data and
avoid asserting the DIR high.

Figures 1 and 2 show the timing diagrams of the DIR
functionality. When the data flows from RXIN to RXOUT,
DIR remains high for 16 bit-times after the last logic-level
low bit within the 8-bit protocol data. This is compliant
with the AISG specification saying that the RS-485 trans­mitter stops driving the bus within 20 bit-times after the
last stop bit is sent.

The input pins DIRMD2 and DIRMD1 define the duration
of the bit time, as shown in Table 1.

IDLE (LOGIC-LEVEL HIGH)

TXIN

IDLE

RXIN

IDLE START BIT BIT0 = 1 BIT1 = 1 BIT2 = 0 BIT3 = 0 BIT4 = 1

RXOUT

t

RX

DIR

t

DIR, SKEW

Figure 1. The MAX9947 on the Tower: Communication Flow is from the Base to the Tower

10 _____________________________________________________________________________________

DIR = 1

BIT5 = 1 BIT6 = 0 BIT7 = 0 STOP BIT

STOP BIT

DIR = 1 FOR OTHER 16 BIT-TIMES

IDLE

TXIN

IDLE

AISG Integrated Transceiver

START

1 1 1

BIT

MAX9947

1 STOP BIT IDLE

0 0 0 0

TXOUT AND RXIN

IDLE

IDLE (LOGIC-LEVEL HIGH)

RXOUT

IDLE (LOGIC-LEVEL LOW)

DIR

t

TX

Figure 2. The MAX9947 on the Tower: Communication Flow is from the Tower to the Base

Table 1. Bit-Time Duration Selector

DIRMD2* DIRMD1* AISG DATA RATE (kbps) UNITY BIT TIME (µs)

0 0 9.6 104.16
0 1 38.4 26.04
1 0 115.2 8.68
1 1 Not used Not used

*DIRMD1 and DIRMD2 are internally pulled down.

+5dBm

-5dBm-5dBm

-25dBm-25dBm

IDLE

f

O

200kHz

400kHz

9kHz

1MHz

1MHz

10MHz 20MHz 30MHz 400MHz 12.75GHz

Figure 3. AISG Standard Modem Spectrum Emission Mask

Applications Information

Emission Output Profile

The AISG standard defines the maximum spectrum emis­sion that all the OOK modulating devices must be compli­ant with. Such a spectrum is represented in Figure 3.

______________________________________________________________________________________ 11

-36dBm-36dBm

-67dBm

-125dBm

The MAX9947 is compliant with the AISG standard.

An external 470pF capacitor connected between RXIN
and ground is recommended for compliance above
25MHz (see the Typical Application Circuit (Connectivity

at the Base) and Typical Application Circuit (Connectivity
at the Tower)).

AISG Integrated Transceiver

External Termination and

AC-Coupling to Feeder Cable

The MAX9947 transceiver works in conjunction with an
external 50I termination. The termination is connected
serially between TXOUT and the feeder cable. It acts as
series termination for the transmitting path (data flowing
from TXIN to TXOUT) and acts as parallel termination
when data is being received on RXIN.

MAX9947

The output of the transmitter is biased at 1.5V to maxi­mize the power-supply rejection ratio and minimize
the emission. It is recommended that the device be
AC-coupled to the feeder cable through either an exter­nal RF filter or a series 100nF capacitor.

Transmission Output Power

The MAX9947 output level at TXOUT can be set by
using two external resistors that connect at the RES and
BIAS pins as shown in the Typical Application Circuit

(Connectivity at the Base) and Typical Application
Circuit (Connectivity at the Tower). The maximum volt-

age at TXOUT is 2.52V

. Assuming that the feeder

P-P

cable is terminated into a 50I impedance, the external
filter is lossless at 2.176MHz, and a series 50I termina­tion is being used as in the Typical Application Circuit

(Connectivity at the Base) and Typical Application Circuit
(Connectivity at the Tower), the output level of 2.52V

corresponds to +6dBm at the feeder cable.

The TXOUT voltage level can be varied according to the
following equations:

V

(V

TXOUT

V

TXOUT

) = (2.52V

P-P

V

(V) = 1.5V x R2/(R1 + R2)

RES

(V

) = 2.52V

P-P

x V

P-P

x R2/(R1 + R2)

P-P

(V))/1.5V

RES

Use R1 = 0I for maximum voltage level of 2.52V

The voltage at the RES pin must be between 0.84V and

1.5V. It implies that the minimum voltage level at TXOUT
is approximately 1.41V that corresponds to +1dBm at the
feeder cable. It is recommended that a 1µF capacitor be
connected between the BIAS pin and ground.

To obtain the nominal power level of +3dBm at the
feeder cable as the AISG standard requires, use R1 =

4.1kI and R2 = 10kI that provide 1.78V

The MAX9947 can provide up to 2.52V

at TXOUT.

P-P

to compensate

P-P

for potential loss within the external filter, cable, connec­tions, and termination.

P-P

Receiver-Input Range and Threshold

The maximum OOK input power at RXIN into the 50I
external termination is +5dBm. For a single-tone signal
at 2.176MHz, 5dBm corresponds to 1.12V

The MAX9947 internal threshold is -15dBm (112.4mV

P-P

.

)

P-P

with Q3dB accuracy in compliance with the AISG stan­dard specifications. This threshold sets the minimum
input signal level that is recognized as OOK carrier
being present (level logic-low).

Consider a corner case where the OOK signal at

2.176MHz present at the RXIN pin is at the minimum level
of -15dBm Q3dB. To avoid the saturation of the receiver
input stage, any other adjacent carrier with power-up to
+5dBm must be either below 1.1MHz or above 4.5MHz.

External Clock

The MAX9947 integrated AISG transceiver operates
with an external crystal at 4x the 2.176MHz frequency,
or 8.704MHz. The crystal is required to achieve the
Q100ppm frequency stability specification of the AISG
standard. A crystal with Q30ppm is recommended
along with two 40pF (Q10% tolerance) capacitors con­nected to ground as shown in Typical Application Circuit
(Connectivity at the Base) and Typical Application Circuit

P-P

the oscillation frequency.

(Connectivity at the Tower). The capacitors do not affect

Multiple MAX9947 devices can share the same crystal
by using the SYNCOUT pin. One device acts as a mas­ter and provides the 8.704MHz clock signal to the slave
device(s) through such a pin. To configure a device as a
slave, XTAL2 should be connected to ground. The exter­nal clock coming from the master device feeds the XTAL1
pin of the slave device through a series 10kI resistor.

.

Connect a 1kI pullup resistor to VCC from the SYNCOUT
pin of the master device.

12 _____________________________________________________________________________________

AISG Integrated Transceiver

Typical Application Circuit (Connectivity at the Base)

MAX9947

12V

0.1FF 0.1FF

3.3V

POWER

SUPPLY

5.0V

8.704MHz

FPGA

V

XTAL1

XTAL2

TXIN

DIRMD1

DIRMD2

DIR

RXOUT

GND

V

L

CC

DIRECTION
DETECTION

STATE MACHINE

ANALOG
SWITCH

R2

RES

REF

-15dBm

R1

BIAS

+7dBm TO +12dBm

OOK

DEMODULATOR

1FF

MAX9947

1.5V

BANDPASS FILTER

BANDPASS FILTER

TXOUT

50I

SYNCOUT

Tx POWER:

+1dBm TO

+6dBm

RXIN

C

= 470pF

F

COAX

CABLE

AC-

COUPLING

______________________________________________________________________________________ 13

AISG Integrated Transceiver

Typical Application Circuit (Connectivity at the Tower)

MAX9947

RS-485 BUS
TO TMA/RET

12V

5V

V

CC

MAX13486E
MAX13485E

A

B

GND

0.1FF 0.1FF

3.3V

POWER

SUPPLY

5.0V

8.704MHz

RO

RE

DE

DI

V

XTAL1

XTAL2

TXIN

DIRMD1

DIRMD2

DIR

RXOUT

GND

V

L

CC

DIRECTION
DETECTION

STATE MACHINE

ANALOG
SWITCH

R2

RES

REF

-15dBm

R1

BIAS

+7dBm TO +12dBm

OOK

DEMODULATOR

1FF

MAX9947

BANDPASS FILTER

1.5V

BANDPASS FILTER

TXOUT

50I

SYNCOUT

Tx POWER:

+1dBm TO

+6dBm

RXIN

CF = 470pF

COAX
CABLE

AC-

COUPLING

Chip Information

PROCESS: BiCMOS

14 _____________________________________________________________________________________

AISG Integrated Transceiver

Package Information

For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”,
or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.

PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO.

16 TQFN-EP T1633F+3

21-0136 90-0033

MAX9947

______________________________________________________________________________________ 15

AISG Integrated Transceiver

Package Information (continued)

For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”,
or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.

MAX9947

16 _____________________________________________________________________________________

AISG Integrated Transceiver

Revision History

MAX9947

REVISION

NUMBER

0 12/09 Initial release —
1 9/10 Corrected Figures 1 and 3, added soldering temperature 2, 10, 11
2 6/11 Changed top mark in Ordering Information 1
3 7/11

REVISION

DATE

DESCRIPTION

Added qJA and qJC data

PAGES

CHANGED

2

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Maxim reserves the right to change the circuitry and specifications without notice at any time.

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