SM8613AV Laser Switching Driver IC OVERVIEW The SM8613AV is a portable CD player laser diode (LD) driver IC. Conventional portable CD players use a fixed-current LD drive method, but this increases the power dissipation and limits battery life. The SM8613AV employs an intermittent LD driver duty operation to reduce the laser power dissipation, which greatly reduces the current consumption when reading data and extends battery driver life. FEATURES ■ ■ ■ ■ ■ ■ ■ ■ PINOUT 2.3V low-voltage supply operation Intermittent-duty laser driver built-in (4-times speed read, 38MHz max. intermittent output) Laser switching frequency range: 8.6 to 38MHz Fixed-current drive/intermittent-duty drive switch function Intermittent current duty ratio adjust function Automatic power control (APC) function using luminosity-monitoring photodiode (PD) Low power dissipation Package: 16-pin VSOP (lead-free) (Top view) LDISET 1 16 NC NC MUTE CGAIN PCK VDD LDIOUT DUTY PLSON LDON NC APPLICATIONS NC 8 VSS 9 PDVIN Portable CD player Package SM8613AV 16-pin VSOP (Unit: mm) Weight: 0.07g + 0.1 0.05 0.275typ 5.1 0.2 0.15 - 0.10 0.05 Device PACKAGE DIMENSIONS 4.4 0.2 6.4 0.2 ORDERING INFORMATION 1.15 0.1 ■ RGAIN 0 to 10 0.65 0.10 + 0.1 0.22 - 0.05 0.12 M 0.5 0.2 NIPPON PRECISION CIRCUITS INC.—1 SM8613AV BLOCK DIAGRAM VDD LDISET LDON RLD PLSON Pick-up MUTE Processor PCK DUTY 2 multiplier Pulse control logic Duty rate adjustor Laser diode driver Feedback V-I amplifier RDUTY LDIOUT PDVIN VSS RGAIN CGAIN RG CG NIPPON PRECISION CIRCUITS INC.—2 SM8613AV PIN DESCRIPTION Number Name i/o Description 1 LDISET o LD drive maximum current setting resistor connection 2 NC – No connection (must be open) Intermittent-drive stop signal MUTE 3 MUTE ip Laser drive state L LD intermittent drive control (PLSON = H) H LD constant-current drive 4 PCK i Intermittent control reference pulse input 5 DUTY o Intermittent-duty ratio adjust resistor connection Intermittent-drive control signal PLSON 6 PLSON ip Laser drive state L LD constant-current drive H LD intermittent drive control 7 NC – No connection (must be open) 8 VSS – Ground (0V DC) 9 PDVIN i Laser luminosity monitor voltage input 10 NC – No connection (must be open) LD drive current control signal LDON 11 LDON ip Laser drive state L LD drive stop control (sleep mode) H LD drive ON 12 LDIOUT o LD drive current output 13 VDD – Supply voltage (2.5V DC) 14 CGAIN o APC frequency response control capacitor connection 15 NC – No connection (must be open) 16 RGAIN o APC loop gain control resistor connection ip: Built-in pull-down resistor NIPPON PRECISION CIRCUITS INC.—3 SM8613AV SPECIFICATIONS Absolute Maximum Ratings Parameter Symbol Rating Unit Supply voltage VDD − 0.5 to 7.0 V Input voltage VIN − 0.5 to VDD + 0.5 V Input current IIN − 3.0 to + 3.0 mA Operating temperature TOPR − 20 to 70 °C Storage temperature TSTG − 40 to 125 °C PW 96 mW Power dissipation DC Electrical Characteristics VDD = 2.5V, Ta = + 25 °C unless otherwise noted Rating Parameter Guaranteed operating supply voltage Current consumption Symbol Unit Test level 3.3 V I 1.7 2.3 mA I – 30 µA I Unit Test level Condition VDD IDD1 PDVIN–LDIOUT short, RLDIOUT = 4Ω, LDON = HIGH, Excluding LDIOUT current IDD2 LDON = LOW min typ max 2.3 2.5 1.0 – Input Specifications VDD = 2.5V, Ta = + 25 °C unless otherwise noted Rating Parameter Symbol Condition min typ max PCK HIGH-level voltage VIHPCK VDD × 0.7 – – V I PCK LOW-level voltage VILPCK – – VDD × 0.3 V I PCK HIGH-level sink current IHPCK – – 20 µA I LDON HIGH-level voltage VIHLDON VDD × 0.7 – – V I LDON LOW-level voltage VILLDON – – VDD × 0.3 V I LDON HIGH-level sink current IHLDON – – 20 µA I PLSON HIGH-level voltage VIHPLSON VDD × 0.7 – – V I PLSON LOW-level voltage VILPLSON – – VDD × 0.3 V I PLSON HIGH-level sink current IHPLSON – – 20 µA I MUTE HIGH-level voltage VIHMUTE VDD × 0.7 – – V I MUTE LOW-level voltage VILMUTE – – VDD × 0.3 V I MUTE HIGH-level sink current IHMUTE – – 20 µA I NIPPON PRECISION CIRCUITS INC.—4 SM8613AV Electrical Characteristics VDD = 2.5V, Ta = + 25 °C unless otherwise noted Rating Parameter Symbol Condition min typ max Unit Test level PCK minimum input frequency fPCKMIN – – 4.3 MHz I PCK maximum input frequency fPCKMAX 19 – – MHz I fLD 8.6 – 38 MHz I LDON = LOW to HIGH, I(LDIOUT) to 90%, CG = 6800pF – – 110 µs II Intermittent current output frequency range LDON response time tLDON PLSON, MUTE response time 1 tPLSON1 PLSON = LOW to HIGH (MUTE: LOW), MUTE = HIGH to LOW (PLSON: HIGH), until the duty ratio stabilizes – – 20 µs II PLSON, MUTE response time 2 tPLSON2 PLSON = HIGH to LOW (MUTE: LOW), MUTE = LOW to HIGH (PLSON: HIGH) – – 25 ns II LDIOUT maximum output current ILDMAX PDVIN = 0V 40 – – mA I LDIOUT intermittent current rise time tLDIR – – 10 ns II LDIOUT intermittent current fall time tLDIF – – 10 ns II LDISET voltage VLDISET 1/3VDD 0.75 0.83 0.92 V I PDVIN convergence voltage VPDVIN RG = 33kΩ, VDD = 2.5V, PDVIN–LDIOUT short, RLDIOUT = 20Ω 145 160 175 mV I PDVIN input impedance ZPDVIN 1 – – MΩ II CG = 6800pF – 25 100 kHz I APC loop cutoff frequency fAPC Minimum duty ratio DRMIN PCK = 4.3MHz, RDUTY = 15kΩ 20 – 40 % I Maximum duty ratio DRMAX PCK = 4.3MHz, RDUTY = 5kΩ 55 – 85 % I Minimum LD current ON time tLDION – 14 – ns II Note 1) LDON has internal pull-down resistor. Note 2) PLSON has internal pull-down resistor. Note 3) MUTE has internal pull-down resistor. Note 4) LDISET is in high-impedance state when LDON is HIGH. Note 5) DUTY is in high-impedance state when LDON is HIGH. Test level description Test level I 100% of devices tested at + 25°C Test level II Specifications guaranteed according to design and evaluation tests. NIPPON PRECISION CIRCUITS INC.—5 SM8613AV FUNCTIONAL DESCRIPTION LD Driver Control The LD is controlled by the 3 logic-level signals on LDON, PLSON, and MUTE. When LDON is HIGH, the LD is in drive mode and the drive current is output on LDIOUT. When LDON is LOW (sleep mode), the LD drive mode stops (LDIOUT output current = 0mA). Also when LDON is HIGH, LD intermittent drive mode operation occurs when PLSON is HIGH and MUTE is LOW. Table 1. Control signals and laser drive states LDON PLSON MUTE Laser drive state H L L LDIOUT constant-current output H L H LDIOUT constant-current output H H L LDIOUT intermittent current output H H H LDIOUT constant-current output L × × LDIOUT = 0mA (sleep mode) Note) × : Don’t care. Frequency Multiplier Function and LD Drive Current Duty Ratio Setting The SM8613AV multiplies the PCK input frequency by 2, which is then used as the intermittent-drive reference frequency. The intermittent drive LD current ON time is shown in the following figure. PCK large current I(LDIOUT) time a b duty ratio (a/b) control The intermittent current output from LDIOUT is automatically adjusted as the frequency changes to maintain the duty ratio almost constant. The intermittent current duty ratio is set by resistor RDUTY connected between DUTY and VSS pins, and is given by the following equation. 3 V(DUTY) dutyratio = 1− 2 1 VDD 2 V(DUTY) = × 100 = 44[kΩ] − 2 × RDUTY × 100 [%] RDUTY + 44[kΩ] RDUTY × VDD [V] RDUTY + 44[kΩ] RDUTY : resistor connected to DUTY pin [kΩ] NIPPON PRECISION CIRCUITS INC.—6 SM8613AV Laser Diode Drive Current Mid-value Set Function The laser diode drive current mid-value can be adjusted by changing the resistance RLD connected between the LDISET and VSS pins. The laser diode drive current mid-value reference value ILD0, given by the following equation, is set to the LDIOUT output current when the PDVIN voltage is in balance state (147 to 193mV). Note that the actual LDIOUT current may change due to feedback gain, and laser diode/photo diode tolerance variations. If RG is not connected, the output current has no relationship to the reference current value, but is determined by the PDVIN convergence voltage. ILD0 = ILDSET × 120 = 40VDD [A] RLD RLD : LDISET connected resistor [Ω] APC Loop Gain Setting The APC loop gain can be adjusted using an external resistor RG. The gain set resistor, RG, is connected between RGAIN and CGAIN. The PDVIN voltage to laser drive current open-loop gain is given approximately by the following equation. GmPDVIN = 1.15 × 10 −4 RG [S] ∆LDIOUT current /∆PDVIN voltage ratio [S] RG : RGAIN–CGAIN resistor [Ω] If the external resistor RG is removed, the maximum gain Gm = 26 [S] is selected. APC Loop Cutoff Frequency Setting The APC loop cutoff frequency fAPC is determined by the capacitor CG connected between CGAIN and VSS pins. The same result occurs if CG is connected between RGAIN and CGAIN pins. fAPC = 1 2π950CG [Hz] NIPPON PRECISION CIRCUITS INC.—7 SM8613AV Laser APC Convergence Current External Signal Adjustment The LD convergence current is determined by the internal bias voltage. However, if the APC loop gain resistor RG is small, the convergence current can be adjusted externally. The convergence current is adjusted by the LDISET current, shown in the figure below. With VCTR in the range 0 to 1/3VDD, the LDISET current decreases with increasing VCTR, and the laser convergence current center point also decreases in response. RLD LDISET VCTR (0 to VDD/3) RGAIN RG → small (approximately 3kΩ) CGAIN CG NIPPON PRECISION CIRCUITS INC. reserves the right to make changes to the products described in this data sheet in order to improve the design or performance and to supply the best possible products. Nippon Precision Circuits Inc. assumes no responsibility for the use of any circuits shown in this data sheet, conveys no license under any patent or other rights, and makes no claim that the circuits are free from patent infringement. Applications for any devices shown in this data sheet are for illustration only and Nippon Precision Circuits Inc. makes no claim or warranty that such applications will be suitable for the use specified without further testing or modification. The products described in this data sheet are not intended to use for the apparatus which influence human lives due to the failure or malfunction of the products. Customers are requested to comply with applicable laws and regulations in effect now and hereinafter, including compliance with export controls on the distribution or dissemination of the products. Customers shall not export, directly or indirectly, any products without first obtaining required licenses and approvals from appropriate government agencies. NIPPON PRECISION CIRCUITS INC. 4-3, Fukuzumi 2-chome, Koto-ku, Tokyo 135-8430, Japan Telephone: +81-3-3642-6661 Facsimile: +81-3-3642-6698 http://www.npc.co.jp/ Email: [email protected] NC0112AE 2001.12 NIPPON PRECISION CIRCUITS INC.—8