U4254BM-M ATMEL | Alldatasheet
Document overview
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Technical content
Features
High Dynamic Range for AM and FM Integrated AGC for FM High Intercept Point 3rd-order for FM FM Amplifier Adjustable to Various Cable Impedances High Intercept Point 2nd-order for AM Low-noise Output Voltage Low-power Consumption Electrostatic sensitive device. Observe precautions for handling.
Description
The U4254BM-M is an integrated low-noise AM/FM antenna impedance matching cir- cuit in BiCMOS technology. The device is designed specifically for car applications and is suitable for windshield and roof antennas. Figure 1. Block Diagram
2 U4254BM-M
Figure 2. Pinning SO16
1 FMIN FM input
2 GND1 Ground for FM part
3 FMGAIN FM gain adjustment
5 VREF2 Reference voltage 2 output
6 NC Not connected
7 GND2 Ground for AM part
8 AMIN AM input
9 NC Not connected
10 AMOUT AM output
11 AMOUT1 AM output
12 VREF1 Reference voltage 1 output
13 AGCADJ Adjustment FM wide-band AGC threshold
14 VS Supply voltage
15 FMOUT FM output
16 NC Not connected
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Figure 5. Internal Circuit at Pin AGC Figure 6. Internal Circuit at Pin AGCADJ Figure 7. Internal Circuit at Pin FMOUT
15 FMOUT
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Figure 10. Internal Circuit at Pin VREF1 VREF2 For the DC biasing of the FM amplifier, a second voltage reference circuit is integrated. capacitor to ground of a few nF is recommended. Figure 11. Internal Circuit at Pin VREF2 GND2 GND2 is the ground for the AM amplifier.
4772B–AUDR–11/03 Functional Description The U4254BM-M is an integrated AM/FM antenna impedance matching circuit. It com- pensates cable losses between the antenna (for example windshield, roof or bumper antennas) and the car radio which is usually placed far away from the antenna. The FM amplifier provides excellent noise performance. External components are used to adjust the gain and the input-output matching impedance. Therefore, it is possible to adjust the amplifier to various cable impedances (usually 50, 75 or 150 Ω). To protect the amplifier against input overload, an Automatic Gain Control (AGC) is included on the chip. The AGC observes the AC voltage at the FM amplifier output, rectifies this signal, and delivers DC current to dampen the input antenna signal via an external PIN diode. The threshold for the AGC is adjustable. Simple and temperature-compensated biasing is possible due to the integrated voltage reference V Ref2. The AM part consists of a buffer amplifier. The voltage gain of this stage is approxi- mately one. The input resistance is 470 k Ω, the input capacitance less than 10 pF. The output resistance is 125 Ω. An excellent dynamic range is achieved due to the comple- mentary CMOS source follower stage. Absolute Maximum Ratings Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Reference point is ground (pins 2 and 7) Parameters Symbol Value Unit Supply voltage V S 8.8 V Power dissipation, Ptot at Tamb = 85° CP tot 460 mW Junction temperature T j 150 ° C Ambient temperature T amb -40 to +85 ° C Storage temperature T stg -50 to +150 ° C Electrostatic handling (HBM at ESD S.5.1) ±V ESD ±1000 V Thermal Resistance Parameters Symbol Value Unit Junction ambient R thJA 140 K/W
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4772B–AUDR–11/03
Electrical Characteristics
VS = 8 V, Tamb = 25° C, unless otherwise specified (see Figure 12 on page 9). Parameters Test Conditions Pin Symbol Min. Typ. Max. Unit Supply voltage 14 V S 7 . 288 . 8V Supply currents 14 I S 3.5 4.8 5.6 mA Reference voltage 1 output (I12 =0 ) 1 2 V Ref1 5.1 5.4 5.7 V Reference voltage 2 output (I5 =0 ) 5 V Ref2 2.3 2.6 2.8 V Temperature dependence of VREF2 5 V Ref2/∆T- 1 m V / K AM Amplifier Input resistance 8 R AMIN 470 k Ω Input capacitance 8 C AMIN 10 pF Output resistance 10 R OUT 125 Ω Voltage gain 8, 10 a 0.85 Output noise voltage (rms value) S1 switched to 2 B=6k H z 150 kHz to 300 kHz 500 kHz to 6.5 kHz 10 V VN2 dBµV dBµV 2nd harmonic S2 switched to 1 fAMIN =5 0 0k H z Output voltage = 110 dBµV 10 -65 dBc FM Amplifier Supply current limit I AGC, IAGCADJ =0A 1 5 I 15 33 35 mA Input resistance f = 100 MHz 1 R FMIN 50 Ω Output resistance f = 100 MHz 15 R FMOUT 50 Ω Power gain f = 100 MHz 1, 15 G 5 dB Output noise voltage f = 100 MHz B = 120 kHz 15 V N 0d B µ V 3rd-order output intercept f = 100 MHz 15 132 dBµV AGC AGC input voltage threshold f = 100 MHz S2 switched to 1; AGC threshold DC current is 10 µA at pin 4 V th1 96 dBµV AGC input voltage threshold f = 100 MHz, S2 switched to 2; AGC threshold DC current is 10 µA at pin 4 V th2 106 dBµV AGC output current AGC active I AGC 1.2 mA
Figure 12. Test Circuit
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Figure 13. FM Intermodulation Distortion
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Figure 16. Application Circuit
4772B–AUDR–11/03
Package Information
Ordering Information
Extended Type Number Package Remarks U4254BM-MFP SO16 – U4254BM-MPG3 SO16 Taping corresponding, ICE-286-3 technical drawings according to DIN specifications Dimensions in mm 10.0 9.85 8.89 0.4 1.27 1.4 0.25 0.10 5.2 4.8 3.7 3.8 6.15 5.85 0.2 16 9
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