Motorola MC13028AD, MC13028AP Datasheet

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The MC13028A is a third generation C–QUAM stereo decoder targeted for use in low voltage, low cost AM/FM E.T.R. radio applications. Advanced features include a signal quality detector that analyzes signal strength, signal to noise ratio, and stereo pilot tone before switching to the stereo mode. A “blend function” much like FM stereo has been added to improve the transition from mono to stereo. The audio output level is adjustable to allow easy interface with a variety of AM/FM tuner chips. The external components have been minimized to keep the total system cost low.

• Adjustable Audio Output Level

• Stereo Blend Function

• Stereo Threshold Adjustment

• Operation from 2.2 V to 12 V Supply

• Precision Pilot Tone Detector

• Forced Mono Function

• Single Pinout VCO

• IF Amplifier with IF AGC Circuit

• VCO Shutdown Mode at Weak Signal Condition

The purchase of the Motorola C–QUAMAM Stereo Decoder does not carry with such purchase any license by implication, estoppel or otherwise, under any patent rights of Motorola or others covering any combination of this decoder with other elements including use in a radio receiver. Upon application by an interested party, licenses are available from Motorola on its patents applicable to AM Stereo radio receivers.

C–QUAM AM STEREO

ADVANCED WIDE VOLTAGE

IF and DECODER for E.T.R. RADIOS

SEMICONDUCTOR

TECHNICAL DATA

P SUFFIX

PLASTIC PACKAGE

CASE 648

D SUFFIX

PLASTIC PACKAGE

CASE 751B

(SO–16)

Representative Block Diagram

VCO

AM Stereo

Decoder

Amp

AGC

This device contains 679 active transistors.

B 8

Signal Quality

MOTOROLA ANALOG IC DEVICE DATA

Detector

Pilot Tone

Detector

Reg

PIN CONNECTIONS

Stereo

Filter

Bypass

Gnd

Stereo

1.0 V

Blend

1 2 3 4 5 6 7 8

Threshold Adjust

910111213141516

AGC Bypass

IF Feedback

IF Signal Input

Indicator Drive

Reference

Right Channel

Output Left Channel

Output Loop Filter

14 13

VCO Output V

Pilot Signal

Input Pilot Q Detector

Output Pilot I Detector

Output

ORDERING INFORMATION

Operating

Device

87654321

MC13028AD MC13028AP DIP–16

 Motorola, Inc. 1996 Rev 2

Temperature Range

TA = –25° to +70°C

Package

SO–16

MC13028A

MAXIMUM RATINGS (

Power Supply Input Voltage Operating Junction Temperature Operating Ambient Temperature Storage Temperature Range LED Indicator Current

ELECTRICAL CHARACTERISTICS (V

@ 50% Modulation, unless otherwise noted.)

Supply Current Drain

VCC = 2.2 V VCC = 8.0 V – 11 –

Audio Output Level, L+R, Mono Modulation V

RO = 1.8 k, VCC = 2.2 V, Input 55 dBµV 22 33 44 RO = 10 k, VCC = 8.0 V, Input 50 dBµV 150 200 250

RO = 10 k, VCC = 8.0 V, Input 40 dBµV 80 130 180 RO = 10 k, VCC = 8.0 V, Input 31 dBµV – 50 –

Audio Output Level, L or R Only, Stereo Modulation V

RO = 1.8 k, VCC = 2.2 V, 55 dBµV Input 35 80 106 RO = 10 k, VCC = 8.0 V 340 460 580

Output THD %

50% Stereo, L or R Only THD1 – 0.6 1.8 50% Mono, L+R THD2 – 0.3 0.6 90% Mono, L+R, Input 86 dBµV THD3 – – 1.5

Channel Separation L or R 23 35 – dB

50% L or R Only

Decoder Input Sensitivity V

= –10 dB

out

Force to Mono Mode, (Pin 10) – 0.25 0.3 – Vdc Stereo Threshold Adjust (Pin 1)

Pin 1 Open R1 = 15 k (Gnd) – 55 – R1 = 680 k (VCC) – 48 –

Signal to Noise Ratio, RO = 10 k S/N dB

50% Stereo, L or R Only 40 62 – 50% Mono, L+R 40 59 –

Input Impedance R

(Reference Specification) C

Maximum Input Signal Level for THD ≤ 1.5% – – – 86 dBµV Blend Voltage

Mono Mode 0.7 – 0.9 Stereo Mode 1.20 1.30 1.35 Out of Lock – 0.12 0.2

VCO Lock Range OSC AGC Range AGC Channel Balance C–B –1.0 – 1.0 dB Pilot Sensitivity – – 2.5 4.0 %

TA = 25°C, unless otherwise noted.)

Rating Symbol Value Unit

Characteristic

stg

LED

= 8.0 Vdc, TA = 25°C, Input Signal Level = 74 dBµV, Modulation = 1.0 kHz

150

–25 to +70

–55 to +150

Vdc

°C °C °C

Symbol Min Typ Max Unit

out

in in

BI Vdc

tun rng

– 9.0 11

mVrms

– 33 – dBµV

dBµV

– 50 55

– 10 – kΩ – 8.0 – pF

– ±2.5 – kHz – 44 – dB

MOTOROLA ANALOG IC DEVICE DATA

MC13028A

Standard T est Circuit

0.47

0.01

Gnd

Pilot Ind

LED

Blend

ÁÁ

MOTOROLA ANALOG IC DEVICE DATA

Symbol

ÁÁÁ

AGC

cap

ÁÁÁ

FBcap

ÁÁÁ

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10 µF

Amp

AGC

AM Stereo

Decoder

Signal Quality

Detector

Reg

Pilot Tone

Detector

PIN FUNCTION DESCRIPTION

Internal Equivalent Circuit

2.4 k

2.0 k

Right

Left

10 k

Audio Output

10 k

VCO

3.6 MHz

2.2 k

Loop

43 pF

47 µF

0.22

0.47

2.2 k

Description/External Circuit Requirements

Stereo Threshold Adjustment Pin

The function of this circuit is to provide the freedom

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to achieve a desired value of incoming IF signal level which will cause full stereo operation of the decoder.

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The level can be determined by the value of R1, a

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resistor from Pin 1 that can be connected to either VCC or to ground. This resistor may also be omitted

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in some designs (Pin 1 left open). The approximate

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dc level with the pin left open is 0.6 Vdc.

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AGC Filter Bypass Capacitor

An electrolytic capacitor is used as a bypass filter

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and it sets the time constant for the AGC circuit

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action. The recommended capacitor value is 10 µF from Pin 2 to ground. The dc level at this pin varies

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as shown in the curve in Figure 13, AGC Voltage versus Input Level.

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IF Amplifier Feedback Capacitor

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A capacitor which is specified to have a low ESR at 450 kHz is normally used at Pin 3. The value

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recommended for this capacitor is 0.47 µF from

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Pin 3 to ground. This component forms a low pass

filter which has a corner frequency around 30 kHz.

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ÁÁ

Symbol

ÁÁÁ

Gnd

ÁÁÁ

MC13028A

PIN FUNCTION DESCRIPTION

Internal Equivalent Circuit

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Gnd

10 k

ref

Substrate

Circuit

Description/External Circuit Requirements

IF Amplifier Input

Pin 4 is the IF input pin. The typical input impedance

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at this pin is 10 k. The input should be ac coupled

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through a 0.01 µF capacitor.

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Supply Ground

In the PCB layout, the ground pin should be

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connected to the chassis ground directly. This pin

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is the internal circuit ground and the silicon substrate ground.

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ÁÁ

IND

ÁÁÁ

Ref

ÁÁÁ

CAP

Blend

ÁÁÁ

Pilot

ÁÁÁ

43 k

30 k

Reference

Voltage

1.0 V

Blend Cap

Charging

Circuit

Blend

Algorithm

Circuit

Pilot Indicator Driver Circuit

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reg

Stereo Indicator Driver

This driver circuit is intended to light an LED or

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other indicator when the decoder receives the

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proper input signals and switches into the stereo mode. The maximum amount of current that the

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circuit can sink is 10 mA.

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A current limiting resistor is applied externally to

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control LED brightness versus total power supply current.

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Regulated Voltage, 1.0 V

An electrolytic capacitor used as a bypass filter is

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recommended from Pin 7 to ground. The capacitor value should be 10 µF.

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Blend Capacitor

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The value of the capacitor on this pin will effect the time constant of the decoder blend function. The

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recommended value is 10 µF from Pin 8 to ground.

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The dc level at Pin 8 is internally generated in response to input signal level and signal quality. This

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pin is a key indicator of the operational state of the IC

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(see text Functional Description). It is recommended to discharge the blend capacitor externally when

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changing stations.

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Pilot I Detector Output

The Pilot I Detector output requires a 10 µF

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electrolytic capacitor to ground. The value of this capacitor sets the pilot acquisition time. The dc

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level at Pin 9 is approximately 1.0 Vdc, unlocked,

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and 1.1 to 2.4 Vdc in the locked condition.

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MOTOROLA ANALOG IC DEVICE DATA

ÁÁ

Symbol

Pilot

ÁÁÁ

PILOT

fil

ÁÁÁ

MC13028A

PIN FUNCTION DESCRIPTION

Internal Equivalent Circuit

5.0 k

30 k

2.0 k

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Description/External Circuit Requirements

Pilot Q Detector Output

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This pin is connected to the Pilot Q detector and requires a 0.47 µF capacitor to ground to filter the

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error line voltage at the PLL pilot tone detector. If the

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value of this capacitor is made too large, the decoder may be prevented from coming back into

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stereo after a signal drop out has been experienced in the field. The force to mono function is also

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accomplished at this pin by pulling the dc voltage

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level at the pin below 1.0 V.

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Pilot Signal Input

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A capacitor to ground forms a filter for the pilot input signal. The recommended value of the capacitor is

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0.22 µF . The dc level at Pin 1 1 is approximately

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1.0 Vdc.

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Supply Voltage (VCC)

The operating supply voltage range is from 1.8 Vdc

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to 12 Vdc.

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ÁÁ

MOTOROLA ANALOG IC DEVICE DATA

OSC

ÁÁÁ

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2.2 k

reg

3.1 k

3.0 k

6.3 pF 15 k

Oscillator Input

The oscillator pin requires a ceramic resonator and

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parallel capacitor connected to ground. The

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recommended source for the ceramic resonator is Murata, part number CSA 3.60MGF108.

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A 43 pF NPO capacitor is in parallel with the resonator. The dc level at Pin 13 is approximately

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1.1 Vdc.

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ÁÁ

Symbol

LOOP

Filter

ÁÁÁ

MC13028A

PIN FUNCTION DESCRIPTION

Internal Equivalent Circuit

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10 k

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390

drive

Fast

Lock

High

Fast

Lock

Low

Description/External Circuit Requirements

Loop Filter

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A capacitor which forms the loop filter is connected from Pin 14 to ground. The recommended value is

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47 µF in series with 47 Ω. This capacitor should be of

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good construction quality so it will have a very low specification for leakage current in order to prevent

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stereo distortion. The 47 Ω resistor in series with the capacitor controls the PLL corner frequency

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response, keeping the response shape critically

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damped and not peaked up. The dc level at Pin 14 is approximately 0.6 Vdc in the locked condition.

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ÁÁ

LEFT

out

ÁÁÁ

RIGHT

out

ÁÁÁ

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1.0 k

Left Channel Audio Output

This is the left channel audio output pin from which

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the IC can provide 1.3 µApp drive current for each

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percent of mono modulation. A resistor to ground sets the level of the audio output.

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For example,

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drive per % mod) = 130 µApp flowing through the

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load resistor. (For a 2.2 k load, 286 mVpp is then the output signal voltage.) When dealing with

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stereo signals, multiply the mod level by 2; i.e. (left only mod) x 2 (stereo factor) x 1.3 µApp (IC

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drive per % mod) = 130 µApp flowing through the

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load resistor.

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Right Channel Audio Output

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This is the right channel audio output pin. A resistor to ground sets the level of the audio output. See the

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explanation under the Left Channel Audio Output

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description above.

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100%

(mono mod) x 1.3 µApp (IC

50%

MOTOROLA ANALOG IC DEVICE DATA

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