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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
I I
PINOUT
(Top view)
I I
I I
I I
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)
LDISET NC MUTE PCK DUTY PLSON NC VSS
1
16
RGAIN NC CGAIN VDD LDIOUT LDON NC
APPLICATIONS
I
8
9
PDVIN
Portable CD player
ORDERING INFORMATION
Device SM8613AV Package 16-pin VSOP
PACKAGE DIMENSIONS
(Unit: mm) Weight: 0.07g
4.4 0.2 6.4 0.2
0.10 0.05
5.1 0.2
1.15 0.1
0.275typ
0.15 -
+ 0.1 5 0.0
0 to 10
0.65
0.10 0.22 - 0.05
+ 0.1
0.12 M
0.5 0.2
NIPPON PRECISION CIRCUITS INC.--1
SM8613AV
BLOCK DIAGRAM
VDD LDISET LDON PLSON MUTE Processor LDIOUT RLD Pick-up
PCK
2 multiplier
Pulse control logic
Laser diode driver
DUTY RDUTY
Duty rate adjustor
Feedback V-I amplifier
PDVIN
VSS RGAIN RG CGAIN CG
NIPPON PRECISION CIRCUITS INC.--2
SM8613AV
PIN DESCRIPTION
Number 1 2 Name LDISET NC i/o o - Description LD drive maximum current setting resistor connection No connection (must be open) Intermittent-drive stop signal MUTE 3 MUTE ip L H 4 5 PCK DUTY i o Laser drive state LD intermittent drive control (PLSON = H) LD constant-current drive
Intermittent control reference pulse input Intermittent-duty ratio adjust resistor connection Intermittent-drive control signal PLSON Laser drive state LD constant-current drive LD intermittent drive control
6
PLSON
ip
L H
7 8 9 10
NC VSS PDVIN NC
- - i -
No connection (must be open) Ground (0V DC) Laser luminosity monitor voltage input No connection (must be open) LD drive current control signal LDON Laser drive state LD drive stop control (sleep mode) LD drive ON
11
LDON
ip
L H
12 13 14 15 16
LDIOUT VDD CGAIN NC RGAIN
o - o - o
LD drive current output Supply voltage (2.5V DC) APC frequency response control capacitor connection No connection (must be open) APC loop gain control resistor connection
ip: Built-in pull-down resistor
NIPPON PRECISION CIRCUITS INC.--3
SM8613AV
SPECIFICATIONS
Absolute Maximum Ratings
Parameter Supply voltage Input voltage Input current Operating temperature Storage temperature Power dissipation Symbol VDD VIN IIN TOPR TSTG PW Rating - 0.5 to 7.0 - 0.5 to VDD + 0.5 - 3.0 to + 3.0 - 20 to 70 - 40 to 125 96 Unit V V mA C C mW
DC Electrical Characteristics
VDD = 2.5V, Ta = + 25 C unless otherwise noted
Rating Parameter Guaranteed operating supply voltage Symbol Condition min VDD PDVIN-LDIOUT short, RLDIOUT = 4, LDON = HIGH, Excluding LDIOUT current LDON = LOW 2.3 typ 2.5 max 3.3 V Unit Test level I
Current consumption
IDD1 IDD2
1.0 -
1.7 -
2.3 30
mA A
I I
Input Specifications
VDD = 2.5V, Ta = + 25 C unless otherwise noted
Rating Parameter PCK HIGH-level voltage PCK LOW-level voltage PCK HIGH-level sink current LDON HIGH-level voltage LDON LOW-level voltage LDON HIGH-level sink current PLSON HIGH-level voltage PLSON LOW-level voltage PLSON HIGH-level sink current MUTE HIGH-level voltage MUTE LOW-level voltage MUTE HIGH-level sink current Symbol VIHPCK VILPCK IHPCK VIHLDON VILLDON IHLDON VIHPLSON VILPLSON IHPLSON VIHMUTE VILMUTE IHMUTE Condition min VDD x 0.7 - - VDD x 0.7 - - VDD x 0.7 - - VDD x 0.7 - - typ - - - - - - - - - - - - max - VDD x 0.3 20 - VDD x 0.3 20 - VDD x 0.3 20 - VDD x 0.3 20 V V A V V A V V A V V A Unit Test level I I I I I I I I I I I I
NIPPON PRECISION CIRCUITS INC.--4
SM8613AV
Electrical Characteristics
VDD = 2.5V, Ta = + 25 C unless otherwise noted
Rating Parameter PCK minimum input frequency PCK maximum input frequency Intermittent current output frequency range LDON response time Symbol fPCKMIN fPCKMAX fLD tLDON LDON = LOW to HIGH, I(LDIOUT) to 90%, CG = 6800pF PLSON = LOW to HIGH (MUTE: LOW), MUTE = HIGH to LOW (PLSON: HIGH), until the duty ratio stabilizes PLSON = HIGH to LOW (MUTE: LOW), MUTE = LOW to HIGH (PLSON: HIGH) PDVIN = 0V Condition min - 19 8.6 - typ - - - - max 4.3 - 38 110 MHz MHz MHz s s Unit Test level I I I II
PLSON, MUTE response time 1
tPLSON1
-
-
20
II
PLSON, MUTE response time 2 LDIOUT maximum output current LDIOUT intermittent current rise time LDIOUT intermittent current fall time LDISET voltage PDVIN convergence voltage PDVIN input impedance APC loop cutoff frequency Minimum duty ratio Maximum duty ratio Minimum LD current ON time
tPLSON2 ILDMAX tLDIR tLDIF VLDISET VPDVIN ZPDVIN fAPC DRMIN DRMAX tLDION
- 40 - -
- - - - 0.83 160 - 25 - - 14
25 - 10 10 0.92 175 - 100 40 85 -
ns mA ns ns V mV M kHz % % ns
II I II II I I II I I I II
1/3VDD RG = 33k, VDD = 2.5V, PDVIN-LDIOUT short, RLDIOUT = 20
0.75 145 1
CG = 6800pF PCK = 4.3MHz, RDUTY = 15k PCK = 4.3MHz, RDUTY = 5k
- 20 55 -
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 Test level II 100% of devices tested at + 25C 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 H H H H L Note) x : Don't care. PLSON L L H H x MUTE L H L H x Laser drive state LDIOUT constant-current output LDIOUT constant-current output LDIOUT intermittent current output LDIOUT constant-current output LDIOUT = 0mA (sleep mode)
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) a b duty ratio (a/b) control time
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) =
x 100 =
44[k] - 2 x RDUTY x 100 [%] RDUTY + 44[k]
RDUTY x VDD [V] RDUTY + 44[k]
RDUTY : resistor connected to DUTY pin [k]
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 x 120 =
40VDD [A] RLD
RLD : LDISET connected resistor []
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 x 10 -4 RG [S]
LDIOUT current /PDVIN voltage ratio [S] RG : RGAIN-CGAIN resistor []
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 2950CG
[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 3k) 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: sales@npc.co.jp
NC0112AE 2001.12
NIPPON PRECISION CIRCUITS INC.--8

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