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U2510B

Rev. A3, 23-Feb-01 1 (15)

All-Band AM/FM Receiver and Audio Amplifier

Description

The U2510B is an integrated bipolar one-chip AM/FM radio circuit. It contains an FM front end with preamplifier, FM IF and demodulator, a complete AM

receiver, an AF amplifier and a mode switch for AM, FM and tape. This circuit is designed for clock radios and portable radio-cassette recorders.

Features

D Superior FM strong signal behavior by using RF AGC D Soft mute and HCC for decreasing interstation noise in FM mode D Excellent AFC performance (level controlled, both polarities available)D Level indicator (LED drive) for AM and FM

D DC mode control: AM, FM and tape

D Wide supply-voltage range and low quiescent current D High AF output power: 1 W D Electronic volume control

D Electronic AF bandwidth control (treble and high cut)D Output stage for headphone and speaker drive

Block Diagram

13912

Figure 1. Block diagram

Rev. A3, 23-Feb-01

2 (15)Order Information

Pin Description

123

45678109

272221

2018

191712

1128

2526

2324

FM-AFC FMOsc

V Ref FMtank

AMtank

FM-AGC

V ol ctrl in AMOsc

FMin

FM-discr

Mute AM/FM detect V AGC/AFC AFC switch IF-GND

LED drive

V Treble in Ripple in

AFin FM-IFin

V S AFout AF-GND

1615

1314812

FE-GND AM/FM IFout

AM-IFin Mode ctrl switch

Figure 2. Pinning

Rev. A3, 23-Feb-01 3 (15)

Terminal Voltages

Test circuit: V in = 0

Rev. A3, 23-Feb-01

4 (15)Absolute Maximum Ratings

Electrical Characteristics

V S = 6 V , T amb = 25°C, test circuit (figure 16), unless otherwise specified

U2510B-M__T: max. 6 V

Rev. A3, 23-Feb-01 5 (15)

Electrical Characteristics (continued)

V S = 6 V , T amb = 25°C, test circuit (figure 16), unless otherwise specified

Rev. A3, 23-Feb-01

6 (15)2

46810024

I ( m A )

S V S ( V )

9510396

Figure 3. Quiescent current

0.01

0.1

110

102030

4050V ( d B )

U f ( kHz )

100

95 10397

Figure 4. AF section

1010010000246810d ( % )

P o ( mW )

1000095 10398

Figure 5. AF section: Distortion

100

1000

10000

P ( m W )o

V S ( V )

9510399

Figure 6. AF section: Max. output power

810

3240

P ( m W )o

V S ( V )

95 10400

Figure 7. AF section: Supply-voltage rejection ratio

–20

02040600

0.40.8

1.2

1.6

2.0

V ( d B V )o

V i ( dB m V )

120

95 10403

100Figure 8. FM section: Mute voltage

Rev. A3, 23-Feb-017 (15)

–100

–80

–60–40–20

V ( d B V )

D V i ( dB m V )

95 10404

Figure 9. AM section: Demodulator output level

0.5

1.52

–80

–60

–40–200

V ( d B V )

O V 4 ( V )

2.5

95 10406

Figure 10. V olume control range characteristics 0

2346

I ( m A )L E D

V i ( dB m V )

120

95 10407

100

Figure 11. AM/FM level indicator current

2002040600

0.4

0.8

1.2

2.0

V ( V )A

G C V i ( dB m V )

120

95 10408

80100Figure 12. AM section: AGC voltage (at Pin 22)

Rev. A3, 23-Feb-01

8 (15)–20

0204060–100

–80–60–40–200

V ( d B V )

D V i ( dB m V )

8095 10401

120

100

Figure 13. FM section: Demodulator output level

–20

0204060

V ( d B V )o

V i ( dB m V )

120

95 10402

80100

68k W 100k W Figure 14. FM section: Audio output level

–20

0204060–100

–80–60–40

–200

V ( d B V )

O V i ( dB m V )

120

95 10405

100

S+N

Figure 15. AM section: Audio output level

Rev. A3, 23-Feb-019 (15)

Test Circuit

Figure 16. Test circuit

Application

General

The U2510B is a bipolar monolithic IC for use in radio sets, for example, headphone receivers, radio recorders and clock radios. The IC contains all AM, FM, AF and switching function blocks necessary to construct these kinds of radio receivers using only few components around the IC. In the design, special efforts were made to get good performance for all AM bands (short and long wave).

The implementation of enhanced functions (options)makes it possible to improve the radio’s performance and to produce radios with interesting features. In this case few (external) parts have to be changed or added. By using all or some of the options offered by the U2510B different types or classes of radios can be designed to the customer’s requirements with the same IC.

One of the general advantages of using the U2510B is the fact that all receiver functions (including the options) are integrated and tested on a system level. Therefore, two additional cost-savings are achieved by:

1.Shorter development time through less technical

problems and

2.Higher reproductivity and low reject level in the set

production line.

Another advantage, due to the technology of the U2510B, is the wide operating voltage range, espe-cially the upper limit (13 V). This feature allows the use of soft power supply for line powered radios which can also reduce the set’s total cost.

Rev. A3, 23-Feb-01

10 (15)Circuit Example

Figure 17 shows a circuit diagram for low end AM/AF radios using the U2510B. Figure 18 shows a circuit diagram of AM/AF radio for higher class designs using all possible options of the U2510B. The layout of the PC board, shown in figure 19, is suitable for both the circuit example shown in figure 17 and the circuit example shown in figure 18. The associated coil, varicon and filter specifications are listed in the table: COIL DATA and SPECIAL COMPONENT PARTS. The circuit diagram (figure 18), has the following options compared to the circuit diagram (figure 17) (the additional parts, which have to be provided, are listed in parentheses):

a)Soft mute and high cut control in FM mode (1 cap.)b)Electronic treble control in AM, FM and TAPE mode

(1 pot.)

c)On-chip mode control for TAPE application d)RF AGC in FM mode (1 capacitor)

e)AFC, adjustable to the correct polarity and slope

(1 cap.)

f)Tuning indication using LED as an indicator

(1 LED, 1 cap.)Option a) reduces the interstation noise by the two functions: soft mute and HCC. Both are controlled by the mute voltage (Pin 1). The soft mute reduces the loudness only, while the HCC reduces the high-end audio cut-off frequency of the audio preamplifier, when the signal level falls below a given threshold. This signal level threshold as well as the mute depth can be reduced by adding a resistor (R 3) or by increasing the FM front–end gain.Option b) allows the treble control for all operating modes without the need of an additional capacitor. This concept leads to a smooth and correct treble control behavior which is an improvement compared to the controlled RC network normally used.

Option c) is very useful for application in radio cassette-recorders, for instance. In TAPE mode, the AM/FM receiver blocks are completely switched off and the signal from the tape recorder can be fed to the audio amplifier ’s input directly. This saves quiescent current and makes the TAPE switching easy. However, to minimize switching noise by the mode switch, the following switch sequence should be chosen: AM, FM,TAPE.

Option d) improves the strong signal behavior by protecting the FM mixer against overload. This is provided by the integrated broad-band-width RF AGC. If necessary, the AGC threshold can be decreased by a resistor, loading Pin 11 to GND (not shown).

Option e) improves the tuning behavior substantially. The special design of the on-chip AFC function means that common disadvantages such as asymmetrical slope,(chip-) temperature effects and unlimited holding range are avoided. As mentioned in the “Pinning Description Table”, the AFC slope has to be inverted when the local oscillator (LO) frequency has to be below the receiving frequency. This can be achieved by connecting Pin 21 to the potential of Pin 8. In addition to the options described above, the following proposals are implemented in the circuit diagram (figure 18), too:

D An FM IFT is applied. This improves the channel selectivity and minimizes substantially the spurious responses caused by the FM ceramic filter (CF 2). With the choice of the winding ratio of this IFT, the FM front end gain can be matched to other values if neces-sary.D In the FM RF input section, the low cost antenna filter (L 5, C 15) is replaced by a special band pass filter (PFWE8). Such a BPF protects the FM front end against the out-off-band interference signals (TV channels, etc.) which could disturb the FM reception.

Design Hints

The value of the power supply blocking capacitor C 13should not be below 470 m F. In addition, this capacitor should be placed near Pin 26. This will help to avoid unacceptable noise generated by noise-radiation from the audio amplifier via the bar-antenna. In designs, where the supply voltage goes below 2.5 V , the value of the blocking capacitor (C 7) should be chosen as 47 m F or even higher.To achieve a high rejection of short wave reception in medium wave operation, the LO amplitude at Pin 5should not exceed approximately 200 mV. This LO amplitude depends on the LO transformer’s Q and its turns ratio. For the LO transformer type described in the “Coil Data Table”, a resistor R 4 (2.2 k W for example) in parallel to the secondary side of the AM LO transformer T 2 is recommended. To minimize feedback effects in the RF/IF part in FM mode, the capacitor C 6 should be placed as near to Pins 8 and 20 as possible.

As shown in the application circuit diagrams (figures 17and 18), in FM mode ceramic filter devices are used for channel selection (CF 2) while for FM, demodulation in LC-discriminator circuit (T 4, C 24, C 25) is used instead of a ceramic discriminator device.

Such an LC discriminator circuit can be easily matched to the FM IF selectivity block by its alignment. The zero-crossing of the discriminator can be detected at the demodulator output (Pin 23). The zero-crossing voltage is equal to half of the regulated voltage at Pin 8.

Rev. A3, 23-Feb-0111 (15)

The alignment of the LC-discriminator circuit should be done with little or no effect on the AFC function. This can be realized by:–switching Pin 21 to open-circuit –connecting Pin 1 to a voltage source of 2 V –using a low signal level for alignment.

In general, ceramic discriminator devices can be used,

too. In this case, the effect of unavoidable spreads in the frequency characteristics of these case ceramic devices in conjunction with the IC characteristic has to be consid-ered. For example, mismatches of the characteristics between selectivity block and FM discriminator will lead to an increased signal-to-noise ratio at low signal level as well as to a higher demodulation distortion level or to an asymmetrical AFC.

Application Circuits

Figure 17. Application circuit (low cost)

Rev. A3, 23-Feb-01

12 (15)

Figure 18. Application circuit (upgraded) R 2 only if V S > 8 V

Figure 19. PC-board

Rev. A3, 23-Feb-0113 (15)

Coil Data and Special Component Part

6324

Coil, bottom view Air coil

AM bar antenna

13931

Figure 20.

Rev. A3, 23-Feb-01

14 (15)Package Information

10.2613044

Package SDIP28

Dimensions in mm

27.5

Rev. A3, 23-Feb-0115 (15)

Ozone Depleting Substances Policy Statement

It is the policy of Atmel Germany GmbH to

1.Meet all present and future national and international statutory requirements.

2.Regularly and continuously improve the performance of our products, processes, distribution and operating systems with respect to their impact on the health and safety of our employees and the public, as well as their impact on the environment.It is particular concern to control or eliminate releases of those substances into the atmosphere which are known as ozone depleting substances (ODSs).

The Montreal Protocol (1987) and its London Amendments (1990) intend to severely restrict the use of ODSs and forbid their use within the next ten years. V arious national and international initiatives are pressing for an earlier ban on these substances.

Atmel Germany GmbH has been able to use its policy of continuous improvements to eliminate the use of ODSs listed in the following documents.

1.Annex A, B and list of transitional substances of the Montreal Protocol and the London Amendments respectively

2.Class I and II ozone depleting substances in the Clean Air Act Amendments of 1990 by the Environmental Protection Agency (EPA) in the USA

3.Council Decision 88/540/EEC and 91/690/EEC Annex A, B and C (transitional substances) respectively.Atmel Germany GmbH can certify that our semiconductors are not manufactured with ozone depleting substances and do not contain such substances.

We reserve the right to make changes to improve technical design and may do so without further notice .Parameters can vary in different applications. All operating parameters must be validated for each customer application by the customer. Should the buyer use Atmel Wireless & Microcontrollers products for any unintended or unauthorized application, the buyer shall indemnify Atmel Wireless & Microcontrollers against all claims,costs, damages, and expenses, arising out of, directly or indirectly, any claim of personal damage, injury or death

associated with such unintended or unauthorized use.

Data sheets can also be retrieved from the Internet: http://www.atmel–https://www.wendangku.net/doc/f81577730.html,

Atmel Germany GmbH, P.O.B. 3535, D-74025 Heilbronn, Germany Telephone: 49 (0)7131 67 2594, Fax number: 49 (0)7131 67 2423