general description the ds1181l is a spread-spectrum clock modulator ic that reduces emi in high clock-frequency-based, digital electronic equipment. using an integrated phase-locked loop (pll), the ds1181l accepts an input clock signal in the range of 20mhz to 134mhz and delivers a spread-spectrum mod - ulated output clock signal. the pll modulates, or dithers, the output clock about the center input frequency at a pin-selectable magnitude, allowing direct emi control and optimization. in addition, through an enable pin the dith - ering can be enabled or disabled for easy comparison of system performance during emi testing. this same input pin also allows the ds1181l output to be three-stated. by dithering the system clock, all the address, data, and timing signals generated from this signal are also dith - ered so that the measured emi at the fundamental and harmonic frequencies is greatly reduced. this is accom - plished without changing clock rise/fall times or adding the space, weight, design time, and cost associated with mechanical shielding. the ds1181l is provided in an 8-pin tssop package and operates over a full automotive temperature range of -40c to +125c. applications lcd panels for tvs, desktop monitors, and notebook and tablet pcs printers features modulates a 20mhz to 134mhz clock with center spread-spectrum dithering selectable spread-spectrum modulation magnitudes of: 0.5% 1.0% 1.5% 2.0% low 75ps cycle-to-cycle jitter spread-spectrum disable mode pin compatible with alliance/pulsecore semiconductor p2040 series devices clock output disable low cost low power consumption 3.3v single voltage supply -40c to +125c temperature range small 8-pin tssop package 19-7502; rev 2; 2/15 typical o perating circuit appears at end of data sheet. +denotes a lead(pb)-free/rohs-compliant package. t = tape and reel. part temp range pin-package DS1181LE+ -40c to +125c 8 tssop DS1181LE+t -40c to +125c 8 tssop sso gnd 12 8 7 crsel smsel1 smsel2 clkin tssop top view 3 4 6 5 v cc ssen ds1181l + gnd sso pll with center- dithered spread- spectrum configuration decode and control smsel1 clkin smsel2 f sso = 20mhz to 134mhz (dithered) v cc v cc f in = 20mhz to 134mhz crsel ssen enable logic ds1181l pin coniguration ordering information block diagram ds1181l 20mhz to 134mhz spread-spectrum clock modulator for lcd panels downloaded from: http:///
stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. voltage range on v cc relative to gnd ............. -0.5v to +4.3v voltage range on any lead relative to gnd ................ -0.5v to (v cc + 0.5v), not to exceed +4.3v operating temperature range ......................... -40c to +125c storage temperature range ............................ -55c to +125c soldering temperature .................. see j-std-020 specification note 1: all voltages referenced to ground. currents into the ic are positive and out of the ic are negative. note 2: time between power applied to device and stable output. (v cc = +3.0v to +3.6v, t a = -40c to +125c, unless otherwise noted.) (v cc = +3.0v to +3.6v, t a = -40c to +125c, unless otherwise noted.) (t a = -40c to +125c, unless otherwise noted.) parameter symbol conditions min typ max units sso duty cycle f ssodc measured at v cc /2 40 60 % sso rise time t r c l = 7pf 1 ns sso fall time t f c l = 7pf 1 ns peak cycle-to-cycle jitter t j t a = -40c to +85c, 10,000 cycles 75 ps power-up time t por (note 2) 50 ms parameter symbol conditions min typ max units supply current i cc c l = 7pf, f in = 134mhz 18 ma smsel1/smsel2/clkin input leakage i il:1 0v < v in < v cc -1 +1 a crsel/ ssen input leakage i il:2 0v < v in < v cc -100 +100 a output leakage (sso) i oz ssen = float -1 +1 a low-level output voltage (sso) v ol i ol = 4ma 0.4 v high-level output voltage (sso) v oh i oh = -4ma 2.4 v parameter symbol conditions min typ max units supply voltage v cc (note 1) 3.0 3.6 v input logic 1 v ih 0.8 x v cc v cc + 0.3 v input logic 0 v il -0.3 0.2 x v cc v input logic float ( ssen , crsel) i float 0v < v in < v cc 1 a sso load c l sso < 80mhz 15 pf 80mhz sso < 134mhz 7 clkin frequency f in 20 134 mhz clkin duty cycle f indc 40 60 % ac electrical characteristics dc electrical characteristics recommended operating conditions absolute maximum ratings ds1181l 20mhz to 134mhz spread-spectrum clock modulator for lcd panels www.maximintegrated.com maxim integrated 2 downloaded from: http:///
spectrum attenuation vs. frequency at different dither amplitudes ds1181l toc06 frequency (mhz) attenuation (db) f out = 72mhz f rbw = 120khz center dither 2% 1.5% 1% 0.5% 10db 13db 15db 17db duty cycle vs. temperature ds1181l toc05 temperature (c) duty cycle (%) 110 60 10 42 44 46 48 50 52 54 56 58 6040 -40 f clkin = 72mhz duty cycle vs. supply voltage ds1181l toc04 v cc (v) duty cycle (%) 3.5 3.4 3.3 3.2 3.1 42 44 46 48 50 52 54 56 58 6040 3.0 3.6 f clkin = 72mhz supply current vs. frequency ds1181l toc03 frequency (mhz) i cc (ma) 120 100 80 60 40 2 4 6 8 10 12 0 20 c l = 7pf v cc = 3.6v v cc = 3.0v supply current vs. temperature ds1181l toc02 temperature (c) i cc (ma) 110 60 10 2 4 6 8 10 12 0 -40 f clkin = 134mhz f clkin = 20mhz c l = 7pf f clkin = 66mhz supply current vs. supply voltage ds1181l toc01 v cc (v) i cc (ma) 3.5 3.4 3.3 3.2 3.1 2 4 6 8 10 12 0 3.0 3.6 f clkin = 134mhz f clkin = 20mhz c l = 7pf f clkin = 66mhz typical operating characteristics (t a = +25c, unless otherwise noted.) ds1181l 20mhz to 134mhz spread-spectrum clock modulator for lcd panels maxim integrated 3 www.maximintegrated.com downloaded from: http:///
detailed description the ds1181l modulates an input clock to generate a cen - ter-dithered spread-spectrum output. a 20mhz to 134mhz clock is applied to the clkin pin. an internal pll dithers the output clock about its center frequency at a user-se - lectable magnitude.spread-spectrum dither magnitude the ds1181l can generate dither magnitudes up to 2%. the desired magnitude is selected using input pins smsel1 and smsel2 as shown in table 1. spread-spectrum dither ratethe output spread-spectrum dither rate is fixed at f in /832. table 2. dither rate table 1. dither magnitude crsel clkin range (mhz) dither rate 0 66 to 134 f in /832 float 33 to 80 1 20 to 38 smsel2 smsel1 magnitude selected (%) 0 0 2.0 0 1 1.5 1 0 1.0 1 1 0.5 pin name function 1 clkin clock input. 20mhz to 134mhz clock input (f in ). 2 smsel1 spread-spectrum magnitude select inputs. these digital inputs select the desired spread-spectrum magnitude as shown in the table below. smsel2 smsel1 magnitude selected (%) 0 0 2.0 3 smsel2 0 1 1.5 1 0 1.0 1 1 0.5 4 gnd ground 5 ssen spread-spectrum enable. three-level input to enable/disable spread-spectrum and to three-state the output. 0 = power-up/spread-spectrum enabled float = sso three-stated 1 = power-up/spread-spectrum disabled (not a bypass mode). 6 sso spread-spectrum clock output. outputs a center-dithered spread-spectrum version of the clock input at clkin. 7 crsel clock range and dither rate select. three-level input that determines the dither rate. see the detailed description section for details. crsel clkin range (mhz) dither rate 0 66 to 134 f in /832 float 33 to 80 1 20 to 38 8 v cc supply voltage pin description ds1181l 20mhz to 134mhz spread-spectrum clock modulator for lcd panels www.maximintegrated.com maxim integrated 4 downloaded from: http:///
spread-spectrum enableon power-up, the output clock (sso) remains three-stat - ed until the internal pll reaches a stable frequency. the ssen input can be used to disable the spread-spectrum modulation and to three-state the sso output. if the ssen pin is pulled high, the spread-spectrum modulation is turned off, but the device still uses the internal pll to gen - erate the clock signal at sso. if the ssen pin is floated, the output is three-stated. applications information power-supply decoupling to achieve best results, it is highly recommended that a decoupling capacitor is used on the ic power-supply pins. typical values of decoupling capacitors are 0.01f and 0.1f. use a high-quality, ceramic, surface-mount capaci - tor, and mount it as close as possible to the v cc and gnd pins of the ic to minimize lead inductance. figure 1. ds1181l spread-spectrum frequency modulation package type package code document no. land pattern no. 8 tssop h8+3 21-0175 90-0248 clkinsmsel1 smsel2 gnd crsel v cc decoupling capacitor v cc sso f in = 20mhz to 134mhz note: in the above configuration with smsel1, smsel2, and ssen connected to gnd as well as crsel connected to v cc , the device is configured with a spread-spectrum magnitude of 2.0%, and allows a clkin between 20mhz and 38mhz. f sso dithered ssen ds1181l f in + (0.5%, 1.0%, 1.5%, or 2.0% of f in ) f in f in - (0.5%, 1.0%, 1.5%, or 2.0% of f in ) f sso time 1 dither cycle rate dither amount(0.5%, 1.0%, 1.5%, or 2.0%) clkin range (mhz) dither rate 20 to 134 f in /832 if ssen = 1 package information for the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages . note that a +, #, or - in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. typical operating circuit ds1181l 20mhz to 134mhz spread-spectrum clock modulator for lcd panels www.maximintegrated.com maxim integrated 5 downloaded from: http:///
revision number revision date description pages changed 0 11/07 initial release. 1 8/08 increased the absolute maximum ratings range from +3.63v to +4.3v. 2 2 2/15 removed automotive reference from data sheet 1 revision history maxim integrated and the maxim integrated logo are trademarks of maxim integrated products, inc. ? 2015 maxim integrated products, inc. 6 maxim integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim integrated product. no circuit patent licenses are implied. maxim integrated reserves the right to change the circuitry and speciications without n otice at any time. the parametric values (min and max limits) shown in the electrical characteristics table are guaranteed. other parametric values quoted in this data sheet are provided for guidance. ds1181l 20mhz to 134mhz spread-spectrum clock modulator for lcd panels for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim integrateds website at www.maximintegrated.com. downloaded from: http:///
|
