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DATA

GND

XTAL0

REXT

CFSK

VCC

RFOUT

GNDRF

VCC

ENABLE

XTAL1

DATACLK

MODE

BAND

PIN CONNECTIONS

FEATURES

Selectable frequency bands:

315-434MHz and 868-928MHz

OOK and FSK modulation

Adjustable output power range

Fully integrated VCO

Supply voltage range: 1.9-3.6V

Very low standby current: 0.1nA @ T

=25

Low supply voltage shutdown

Data clock output for microcontroller

Extended temperature range: -40

C to 125

Low external component count

Typical application compliant with ETSI standard

Ordering Information

Device

Ambiant

Temperature

Range

Package

MC33493

DTB

-40

C to

125

TSSOP14

Technical Data

TANGO3
MC33493/D
Rev. 1.6, 6/2002

PLL tuned UHF
Transmitter for Data
Transfer Applications

Figure 1: Simplified block diagram

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MC33493 Technical Data

MOTOROLA

PIN FUNCTION DESCRIPTION

ABSOLUTE MAXIMUM RATINGS

Notes:
1 Human Body model, AEC-Q100-002 Rev. C.
2 Machine Model, AEC-Q100-003 Rev. E.

TRANSMITTER FUNCTIONAL DESCRIPTION

MC33493 is a PLL tuned low power UHF transmitter. The different modes of operation are controlled by the
microcontroller through several digital input pins. The power supply voltage ranges from 1.9V to 3.6V allowing
operation with a single lithium cell.

PHASE LOCKED LOOP AND LOCAL OSCILLATOR

The VCO is a completely integrated relaxation oscillator. The Phase Frequency Detector (PFD) and the loop filter
are fully integrated. The exact output frequency is equal to: f

RFOUT

= f

XTAL

x [PLL Divider Ratio]. The frequency

band of operation is selected through the BAND pin.

Table 1 provides details for each frequency band selection.

Pin

Name

Description

DATACLK

Clock output to the microcontroller

DATA

Data input

BAND

Frequency band selection

GND

Ground

XTAL1

Reference oscillator input

XTAL0

Reference oscillator output

REXT

Power amplifier output current setting input

CFSK

FSK switch output

VCC

Power supply

RFOUT

Power amplifier output

GNDRF

Power amplifier ground

VCC

Power supply

ENABLE

Enable input

MODE

Modulation type selection input

Parameter

Symbol

Value

Unit

Supply Voltage

GND

- 0.3 to 3.7

Voltage Allowed on Each Pin

GND

- 0.3

to V

+ 0.3

ESD HBM Voltage Capability on Each Pin (note 1)

2000

ESD MM Voltage Capability on Each Pin (note 2)

150

Storage Temperature

-65 to +150

Junction Temperature

+150

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RF OUTPUT STAGE

MOTOROLA

MC33493 Technical Data

Table 1: Band selection and associated divider ratios

An out-of-lock function is performed by monitoring the PFD output voltage. When it exceeds defined limits, the
RF output stage is disabled.

RF OUTPUT STAGE

The output stage is a single ended square wave switched current source. Harmonics are present in the output
current drive. Their radiated absolute level depends on the antenna characteristics and output power. Typical
application demonstrates compliance to ETSI standard.

A resistor R

ext

connected to the REXT pin controls the output power allowing a trade-off between radiated power

and current consumption.

The output voltage is internally clamped to V

(typ. V

1.5V @ T

=25

C).

MODULATION

A low logic level has to be applied on pin MODE to select the On Off Keying (OOK) modulation. This modulation
is performed by switching on/off the RF output stage. The logic level applied on pin DATA controls the output
stage state:

DATA=0

output stage off,

DATA=1

output stage on.

If a high logic level is applied on pin MODE, then Frequency Shift Keying (FSK) modulation is selected. This
modulation is achieved by crystal pulling. An internal switch connected to CFSK pin enables to switch the
external crystal load capacitors. Figure 2 shows the possible configurations: serial and parallel.
The logic level applied on pin DATA controls the state of this internal switch:

DATA=0

switch off,

DATA=1

switch on.

DATA input is internally re-synchronized by the crystal reference signal. The corresponding jitter on the data duty
cycle cannot exceed

1 reference period (

75ns for a 13.56MHz crystal).

This crystal pulling solution implies that the RF output frequency deviation equals the crystal frequency deviation
multiplied by the PLL Divider Ratio (see table 1).

BAND Input

Level

Frequency

Band (MHz)

PLL Divider

Ratio

Crystal Oscillator

Frequency (MHz)

High

315

9.84

434

13.56

Low

868

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MC33493 Technical Data

MOTOROLA

MICROCONTROLLER INTERFACE

Figure 2: Crystal pulling configurations

MICROCONTROLLER INTERFACE

Four digital input pins (ENABLE, DATA, BAND and MODE) enable the circuit to be controlled by a
microcontroller. It is recommended to configure the band frequency and the modulation type before enabling the
circuit.

One digital output (DATACLK) provides to the microcontroller a reference frequency for data clocking. This
frequency is equal to the crystal oscillator frequency divided by 64 (see table 2).

Table 2: DATACLK frequency vs crystal oscillator frequency

STATE MACHINE

Figure 3 details the state machine.

Crystal Oscillator Frequency (MHz)

DATACLK Frequency (kHz)

9.84

154

13.56

212

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STATE MACHINE

MOTOROLA

MC33493 Technical Data

Figure 3: State machine

State 1:

The circuit is in standby mode and draws only a leakage current from the power supply.

State 2:

In this state, the PLL is out of the lock-in range. Therefore the RF output stage is switched off preventing RF
transmission. Data clock is available on pin DATACLK. Each time the device is enabled, the state machine
passes through this state.

State 3:

In this state, the PLL is within the lock-in range. If t<t

PLL_lock_in

then the PLL can still be in acquisition mode. If

PLL_lock_in

, then the PLL is locked.

Data entered on pin DATA are output on pin RFOUT according to the modulation selected by the level applied on
pin MODE.

State 4:

When the supply voltage falls below the shutdown voltage threshold (V

SDWN

) the whole circuit is switched off.

Applying a low level on pin ENABLE is the only condition to get out of this state.

Figure 4 shows the waveforms of the main signals for a typical application cycle.

State 2

PLL out of lock-in range

No RF output

State 1

Standby mode

ENABLE=1

PLL in

lock-in range

battery

< V

shutdown

ENABLE=0

Power ON

AND ENABLE=0

State 3

Transmission mode

ENABLE=0

State 4

Shutdown mode

PLL out of

lock-in range

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Part Number MC33493