SA9614 RF AMPLIFIER FOR DIGITAL SERVO SYSTEM DESCRIPTION SA9614 is a RF amplifier, used for signal conversion and auto laser power control (ALPC) between the CD optical pickup head and decoding chip. SA9614 includes interface of CD optical diode, RF signal amplifier and equalizer, VREF generation circuit, automatic optical power switching circuit (it suits for CD-A/V, CD-R, CD-R/W, CD-ROM). SOP-16-225-1.27 FEATURES * RF amplitude automatic adjustment circuit (it suits for CD-A/V, CDR, CD-R/W, CD-ROM). * RF signal equalizer (including VCA). * Auto laser power control circuit (ALPC). ORDERING INFORMATION * Operating voltage: 3V -7V, power dissipation (150mW @5V). APPLICATIONS Device Package SA9614 SOP-16-225-1.27 * CD Players * VCD Players BLOCK DIAGRAM HANGZHOU SILAN MICROELECTRONICS CO.,LTD Http: www.silan.com.cn REV:1.0 2006.07.28 Page 1 of 8 SA9614 ABSOLUTE MAXIMUM RATING (Tamb=25°C) Characteristics Symbol Rating Unit Power Supply Voltage VDD -0.5 ~ +9 V Operating Temperature Tmax -20 ~ +75 °C Max. Power Dissipation Pmax 500 mW DC ELECTRICAL CHARACTERISTICS Characteristics Symbol Power Supply Voltage Test conditions VDD Photo-Electrical Bias Output Voltage VREF Min. Typ. Max. Unit 3.0 5.0 7.0 V VDD=5V 30 mA VDD=5V 2.5 V AC electrical characteristics (VDD=5V) Characteristics Symbol Diode Monitor signal Input MON Photoelectric Signal Input PD RF Signal Gain GAIN Test conditions Min. Typ. Max. 0.13 Unit V DA11 0 0.60 V KSS213 0 0.15 V PD is input pins, RFO is 15 output pin dB RFG=VREF+1V RFG=VREF-1V VCA Gain Control Range VGA Adjust RFC to make1.6MHz as the maximum advance 1.40 14.55 dB 0.4 2.4 MHZ 1.10 11.80 dB frequency, and BST is no connection. VFC=VREF, RFC=300K Equalizer Center Frequency 1 FC1 VFC=VREF, RFC=50K Input 1.6MHz BST=VREF+1V, BST=VREF-1V, Adjust RFC to Boost Of Equalizer Frequency Center GFC make1.6MHz as the maximum advance frequency, and BST is no connection. HANGZHOU SILAN MICROELECTRONICS CO.,LTD Http: www.silan.com.cn REV:1.0 2006.07.28 Page 2 of 8 SA9614 PIN CONFIGURATION PIN DESCRIPTION Pin no. Pin name I/O 1 RFC I Input for setting the EQ center frequency Pin descriptions 2 LD O APC circuit output pin. 3 MON I Diode monitor signal feedback pin.. 4 PD I Photoelectric signal Input 5 RFM I 6 GND I Ground 7 VREF O OEIC bias output pin.. 8 RFG I Equalizer gain setting pin.. 9 RFAC O Equalizer output pin.. 10 EQIN I Equalizer input pin.. 11 RFO O RF signal amplifier output pin. 12 RFI I RF signal amplitude detect input pin (coupling from RFO). 13 RFRC O 14 BST I Equalizer center frequency setting. pin.. 15 LD_ON I APC circuit switch ON/OFF, low active. 16 VCC I Power supply pin.. RF amplifier inverted side output pin. RF amplifier gain is determined by the resistor connected between RFO pin and RFM pin. RF signal amplitude detect HANGZHOU SILAN MICROELECTRONICS CO.,LTD Http: www.silan.com.cn voltage generate pin (connect RC components). REV:1.0 2006.07.28 Page 3 of 8 SA9614 FUNCTION DESCRIPTION SA9614 includes RF signal amplifier, RF equalizer, RF amplitude detector, auto laser power controller, etc. + - + - RF amplifier The above figure is RF signal channel diagram. PD is input pin of laser pickup head. RFO is the output pin., RFM is the feedback input pin of the amplifier. The feedback resistor of PD input amplifier is designed as 58kΩ, so the low frequency gain of first amplifier is AV1=58K/RIN. The gain of the second amplifier is determined by the resistor Rf connected between RFO pin and RFM pin . AV2=Rf /2K. Then the low frequency gain of RF amplifier is: AV=AV1*AV2=Rf*58K/(RIN*2). Frequency response is determined by the capacitor paralleled with input adder, and the bandwidth of -3dB is 1.8MHz. RF SIGNAL AMPLITUDE DETECTOR The input signal of RF amplitude detector is from the RF amplifier output pin RFO. In order to enlarge the linear range of detect, this circuit adopts DC coupling input and AC coupling input, which refers to the above figure. RFRC connects with RC filter components which determine the filter time constant. RFRC pin will obtain a DC voltage correlated with RF amplitude according to the RFO input signal. HANGZHOU SILAN MICROELECTRONICS CO.,LTD Http: www.silan.com.cn REV:1.0 2006.07.28 Page 4 of 8 SA9614 APC CIRCUIT The constant power circuit is used to generate the constant power when diode is in the different state. APC circuit realizes the constant power by monitoring the receiving power of diode, thereby to stabilize the RF input amplitude. In order to adapt to RF input signal of different disks, APC circuit adds the auto power adjusting function. It is to adjust the output power by detecting the RF input signals and thus to adapt to various disks. In the above figure, MON pin is the constant power monitor pin, LD is driver output pin which connects with a PNP transistor. LD_ON is the enable port of APC circuit, high level active. EQUALIZER (INCLUDE VCA AND OUTPUT STAGE) BST 14 RFC 1 EQ 9 RFAC EQIN 10 RFG VCA 8 VREF EQ circuit EQ curve The equalizer includes controllable gain amplifier VCA , equalizer circuit and signal amplifier. HANGZHOU SILAN MICROELECTRONICS CO.,LTD Http: www.silan.com.cn REV:1.0 2006.07.28 Page 5 of 8 SA9614 RFG is the gain control port of VCA, and EQ_IN is signal input port. When the voltage of RFG is equal to VREF, the low frequency gain is 0dB; when the voltage of RFG is equal to VREF+1V, the gain of VCA is +8dB; when the voltage of RFG is equal to VREF-1V, the gain of VCA is -8dB. In the actual applications, it can adjust the output amplitude through adjusting the voltage of RFG. The signal enters the equalizer after passing through the control gain amplifier. The main parameter center frequency and boost gain can be set by RFC and BST. The center frequency of the equalizer curve can be adjusted by changing the ground resistance of RFC, and the external resistor is usually between 50 KHz and 200 KHz. The center frequency is between 1MHz and 5MHz. Setting the voltage of BST can regulate the boost gain of center frequency. When BST is equal to VREF, the gain is set at +5dB; when BST is equal to VREF+1, the gain is set at +8dB; when BST is equal to VREF-1; the gain is set at -1dB. You will get the needed equalizer curve to satisfy the system design by adjusting RFC and BST. The signal amplitude reduced after equalizing, so we need to add an amplifier to compensate the gain, increase the drive capability and reduce the output resistance. RFAC is the output port of the amplifier. After the signal passing through the last amplifier, the output amplitude is adjusted to the same as before equalizing. HANGZHOU SILAN MICROELECTRONICS CO.,LTD Http: www.silan.com.cn REV:1.0 2006.07.28 Page 6 of 8 SA9614 TEST CIRCUIT 9 RFAC RFG 8 EQIN 10 VREF 7 V CC GND 6 RFO 11 RFM 5 I_V I_V I_V 500 I_V 100 1 /6.3V HANGZHOU SILAN MICROELECTRONICS CO.,LTD Http: www.silan.com.cn RFI 12 RFRC 13 PD 4 14 BST MON 3 LD_ON 15 2 LD 100 /6.3V 1 RFC VCC VCC 16 MICROCOMPUTER TYPICAL APPLICATION CIRCUIT REV:1.0 2006.07.28 Page 7 of 8 SA9614 PACKAGE OUTLINE HANGZHOU SILAN MICROELECTRONICS CO.,LTD Http: www.silan.com.cn 3.9±0.3 5.72±0.25 UNIT: mm 6.0±0.4 SOP-16-225-1.27 REV:1.0 2006.07.28 Page 8 of 8