ICS1574B Integrated Circuit Systems, Inc. User Programmable Laser Engine Pixel Clock Generator Description Features The ICS1574B is a very high performance monolithic phaselocked loop (PLL) frequency synthesizer designed for laser engine applications. Utilizing ICS’s advanced CMOS mixedmode technology, the ICS1574B provides a low cost solution for high-end pixel clock generation for a variety of laser engine product applications. • Supports high resolution laser graphics. PLL/VCO frequency re-programmable through serial interface port to 400 MHz; allows less than ±1.5ns pixel clock resolution. • Laser pixel clock output is synchronized with conditioned beam detect input The pixel clock output (PCLK) frequency is derived from the main clock by a programmable resettable divider. • Ideal for laser printer, copier and FAX pixel clock applications Operating frequencies are fully programmable with direct control provided for reference divider, feedback divider and post-scaler. • • • On-chip PLL with internal loop filter • • • • Single 5 volt power supply Block Diagram On-chip XTAL oscillator frequency reference Resettable, programmable counter gives glitch-free clock alignment Low power CMOS technology Compact – 16-pin 0.150" skinny SOIC package User re-programmable clock frequency supports zoom and gray scale functions Figure 1 1574B 8/31/00 ICS1574B Pin Configuration 1 16 DATA XTAL1 2 15 HOLD 14 TEST (Connect to VSS)) 13 VDD 12 VDDO 11 Reserved (Do Not Connect) ICS1574B PCLKEN XTAL2 3 DATCLK 4 VSS 5 VSS 6 PCLK 7 10 Reserved (Do Not Connect) (Do Not Connect) Reserved 8 9 Reserved (Do Not Connect) 16-Pin Skinny SOIC Pin Descriptions PIN NUMBER 7 1 2 3 4 16 15 14 8, 9, 10, 11 13 12 5, 6 P I N NA M E PCLK PCLKEN X TA L 1 X TA L 2 DAT C L K DATA HOLD Te s t R e s e r ve d VDD VDDO VSS DESCRIPTION P i xe l c l o c k o u t p u t . PCLK Enable (Input). Q u a r t z c r y s t a l c o n n e c t i o n 1 / ex t e r n a l r e f e r e n c e f r e q u e n cy i n p u t . Quartz crystal connection 2. Data Clock (Input). S e r i a l R eg i s t e r D a t a ( I n p u t ) . HOLD (Input). Test. (Must be connected to VSS.) R e s e r ve d . ( D o N o t C o n n e c t . ) PLL system power (+5V. See application diagram). Output stage power (+5V). Device ground. (Both pins must be connected.) 2 ICS1574B PCLK Programmable Divider The ICS1574B has a programmable divider (referred to in Figure 1 as the PCLK divider) that is used to generate the PCLK clock frequency for the pixel clock output. The modulus of this divider may be set to 3, 4, 5, 6, 8, 10, 12, 16 or 20 under register control. The design of this divider permits the output duty factor to be 50/50, even when an odd modulus is selected. The input frequency to this divider is the output of the PLL post-scaler described below: The phase of the PCLK output is aligned with the internal high frequency PLL clock (FVCO) immediately after the assertion of the PCLKEN input pulse (active low if PCLKEN_POL bit is 0 or active high if PCLKEN_POL bit is 1). TK = K • TVCO When PCLKEN is deasserted, the PCLK output will complete its current cycle and remain at VDD until the next PCLKEN pulse. The minimum time PCLKEN must be disabled (TPULSE) is 1/FPCLK. Td = LOGIC PROP.DELAY TIME (typically 9ns with a 10pF load on PCLK) TVCO = 1/FVCO Figure 2b See Figure 2a for an example of PCLKEN enable (negative polarity) vs. PCLK timing sequences. The resolution of Ton is one VCO cycle. The time required for a PCLK cycle start following a PCLKEN enable is described by Figure 2b and the following table: K Va l u e s Figure 2a P C L K D iv i d e r K 3 4a 4b 5 6 8a 8b 10 12 16a 16b 20 2 3.5 3 4.5 3.5 5.5 5 7 6.5 9.5 9 12 Typical values for Tr and Tf with a 10pF load on PCLK are 1ns. 3 ICS1574B PLL Post-Scaler back divider makes use of a dual-modulus prescaler technique that allows the programmable counters to operate at low speed without sacrificing resolution. This is an improvement over conventional fixed prescaler architectures that typically impose a factor-of-four (or larger) penalty in this respect. A programmable post-scaler may be inserted between the VCO and the PCLK divider of the ICS1574B. This is useful in generating lower frequencies, as the VCO has been optimized for high-frequency operation. The post-scaler is not affected by the PCLKEN input. Table 1 permits the derivation of “A” & “M” converter programming directly from desired modulus. The post-scaler allows the selection of: • VCO frequency Digital Inputs • VCO frequency divided by 2 The programming of the ICS1574B is performed serially by using the DATCLK, DATA, and HOLD pins to load an internal shift register. • VCO frequency divided by 4 • AUX-EN Test Mode PLL Synthesizer Description — Ratiometric Mode DATA is shifted into the register on the rising edge of DATCLK. The logic value on the HOLD pin is latched at the same time. When HOLD is low, the shift register may be loaded without disturbing the operation of the ICS1574B. When high, the shift register outputs are transferred to the control registers, and the new programming information becomes active. Ordinarily, a high level should be placed on the HOLD pin when the last data bit is presented. See Figure 3 for the programming sequence. The ICS1574B generates its output frequencies using phaselocked loop techniques. The phase-locked loop (or PLL) is a closed-loop feedback system that drives the output frequency to be ratiometrically related to the reference frequency provided to the PLL (see Figure 1). The reference frequency is generated by an on-chip crystal oscillator or the reference frequency may be applied to the ICS1574B from an external frequency source. The PCLKEN input polarity may be programmed under register control via Bit 39. The phase-frequency detector shown in the block diagram drives the voltage-controlled oscillator, or VCO, to a frequency that will cause the two inputs to the phase-frequency detector to be matched in frequency and phase. This occurs when: F(VCO): = F(XTAL1) • Feedback Divider Reference Divider This expression is exact; that is, the accuracy of the output frequency depends solely on the reference frequency provided to the part (assuming correctly programmed dividers). Figure 3 The VCO gain is programmable, permitting the ICS1574B to be optimized for best performance at all operating frequencies. Output Description The PCLK output is a high-current CMOS type drive whose frequency is controlled by a programmable divider that may be selected for a modulus of 3, 4, 5, 6, 8, 10, 12, 16 or 20. It may also be suppressed under register control via Bit 46. The reference divider may be programmed for any modulus from 1 to 128 in steps of one. The feedback divider may be programmed for any modulus from 37 through 392 in steps of one. Any even modulus from 392 through 784 can also be achieved by setting the “double” bit which doubles the feedback divider modulus. The feed- 4 ICS1574B Programming Notes Reference Oscillator and Crystal Selection The ICS1574B has circuitry on-board to implement a Pierce oscillator with the addition of only one external component, a quartz crystal. Pierce oscillators operate the crystal in anti- (also called parallel-) resonant mode. See the AC Characteristics for the effective capacitive loading to specify when ordering crystals. Series-resonant crystals may also be used with the ICS1574B. Be aware that the oscillation frequency will be slightly higher than the frequency that is stamped on the can (typically 0.025 – 0.05%). • VCO Frequency Range: Use the post-divider to keep the VCO frequency as high as possible within its operating range. • Divider Range: For best results in normal situations keep the reference divider modulus as short as possible (for a frequency at the output of the reference divider in the few hundred kHz to several MHz range). If you need to go to a lower phase comparator reference frequency (usually required for increased frequency accuracy), that is acceptable, but jitter performance will suffer somewhat. • VCO Gain Programming: Use the minimum gain which can reliably achieve the VCO frequency desired, as shown here: As the entire operation of the phase-locked loop depends on having a stable reference frequency, we recommend that the crystal be mounted as closely as possible to the package. Avoid routing digital signals or the ICS1574B outputs underneath or near these traces. It is also desirable to ground the crystal can to the ground plane, if possible. If an external reference frequency source is to be used with the ICS1574B, it is important that it be jitter-free. The rising and falling edges of that signal should be fast and free of noise for best results. • The loop phase can be locked to either the rising or falling edges of the XTAL1 input signals, and is controlled by Bit 56. Power-On Initialization The ICS1574B has an internal power-on reset circuit that performs the following functions: VCO GAI N MA X F R E QU E N C Y 4 5 6 7 100 MHz 200 MHz 300 MHz 400 MHz Phase Detector Gain: For most applications and divider ranges, set P [1, 0] = 10 and set P[2] = 1. Under some circumstances, setting the P [2] bit “on” can reduce jitter. During operation at exact multiples of the crystal frequency, P[2] bit = 0 may provide the best jitter performance. Board Test Support It is often desirable to statically control the levels of the output pins for circuit board test. The ICS1574B supports this through a register programmable mode, AUX-EN. When this mode is set, a register bit directly controls the logic level of the PCLK pin. This mode is activated when the S[0] and S[1] bits are both set to logic 1. See Register Mapping for details. 1) Selects the modulus of the PCLK divider to be four (4). 2) Sets the multiplexer to pass the reference frequency to PCLK divider input. These functions should allow initialization for most applications that cannot immediately provide for register programming upon system power-up. Because the power-on reset circuit is on the VDD supply, and because that supply is filtered, care must be taken to allow the reset to de-assert before programming. A safe guideline is to allow 20 microseconds after the VDD supply reaches 4 volts. 5 ICS1574B Power Supplies and Decoupling The ICS1574B has two VSS pins to reduce the effects of package inductance. Both pins are connected to the same potential on the die (the ground bus). BOTH of these pins should connect to the ground plane of the PCB as close to the package as is possible. should have low series inductance and be mounted close to the ICS1574B. The VDD pin is the power supply pin for the PLL synthesizer circuitry and other lower current digital functions. We recommend that RC decoupling or zener regulation be provided for this pin (as shown in the recommended application circuitry). This will allow the PLL to “track” through power supply fluctuations without visible effects. See Figure 4 for typical external circuitry. The ICS1574B has a VDDO pin which is the supply of +5 volt power to the output driver. This pin should be connected to the power plane (or bus) using standard high-frequency decoupling practice. That is, capacitors Figure 4 6 ICS1574B Register Mapping — ICS1574B NOTE: It is not necessary to understand the function of these bits to use the ICS1574B. PC Software is available from ICS to automatically generate all register values based on requirements. Contact factory for details. BIT(S) BIT REF. DESCRIPTION 1–4 PCLK[0]..PCLK[3] Sets PCLK divider modulus according to this table. These bits are set to implement a divide-by-four on power-up. PCLK[ 3] 0 0 0 0 0 0 0 0 1 1 1 1 PCLK[ 2] 0 0 0 0 1 1 1 1 X X X X PCLK[ 1] 0 0 1 1 0 0 1 1 0 0 1 1 PCLK[ 0] 0 1 0 1 0 1 0 1 0 1 0 1 MODUL US 3 4( a ) 4( b) 5 6 8( a ) 8( b) 10 12 16( a ) 16( b) 20 (X = Don't Care) 5, 6 Reserved Must be set to 0. 7 Reserved Must be set to 1. 8 SELXTAL Normally set to 0. When set to logic 1, passes the reference frequency to the post-scaler instead of the PLL output (defaults to 1 on power-up). 9 Reserved Must be set to 0. 10 Reserved Must be set to 1. 11, 12 Reserved Must be set to 0. 13 – 14 S[0]..S[1] PLL post-scaler / test mode select bits. S[1] S[0] 0 0 0 1 1 0 1 1 7 DESCRI PTI ON Post-scaler = 1. F(CLK) = F(PLL). The output of the PCLK divider drives the PCLK output. Post-scaler = 2. F(CLK) = F(PLL)/2. The output of the PCLK divider drives the PCLK output. Post-scaler = 4. F(CLK) = F(PLL)/4. The output of the PCLK divider drives the PCLK output. AUX-EN TEST MODE. The AUX_PCLK bit drives the PCLK output. ICS1574B BIT(S) BIT REF. DESCRIPTION 15 Reserved Must be set to 0. 16 AUX_PCLK Must be set to 0 except when in the AUX-EN test mode. When in the AUX-EN test mode, this bit controls the PCLK output. 17 – 24 Reserved Must be set to 0. 25 – 27 V[0]..V[2] Sets the gain of VCO V[ 2] V[ 1] V[ 0] 1 1 1 1 0 0 1 1 0 1 0 1 VCO GAI N ( MHz / Vo l t ) 30 45 60 80 28 Reserved Must be set to 1. 29 – 30 P[0]..P[1] Sets the gain of the phase detector according to this table: P[1] P[0] 0 0 1 1 0 1 0 1 GAI N ( µA/ r a di a n) 0. 05 0. 15 0. 5 1. 5 31 Reserved Must be set to 0. 32 P[2] See text. Phase detector tuning bit. Should normally be set to one. 33 – 38 M[0]..M[5] M counter control bits. Modulus = value + 1. 39 PCLKEN_POL When = 0, PCLK output enabled when PCLKEN input is low. When = 1, PCLK output enabled when PCLKEN input is high. 40 DBLFREQ 12 /14). Doubles modulus of dual-modulus prescaler (from 6 / 7 to 41 – 44 A[0]..A[3] Controls A counter. When set to zero, modulus = 7. Otherwise, modulus = 7 for "value" underflows of the prescaler, and modulus = 6 thereafter until M counter underflows. 8 ICS1574B BIT(S) BIT REF. DESCRIPTION 45 Reserved Must be set to 1. 46 PCLK_EN Must be set to 0. Disables the PCLK divider when set to 1 regardless of PCLKEN input state. 47, 48 Reserved Must be set to 0. 49 – 55 R[0]..R[6] Reference divider modulus control bits. Modulus = value +1. 56 REF_POL PLL locks to rising edge of XTAL1 input when REFPOL = 1, falling edge of XTAL1 when REFPOL = 0. 9 ICS1574B Table 1 — "A" & "M" Divider Programming Feedback Divider Modulus Table A[2]..A[0]- 001 010 011 100 101 110 111 000 A[2]..A[0]- 001 M[5]..M[0] 010 011 100 101 110 111 000 M[5]..M[0] 000000 000001 13 000010 19 20 000011 25 26 27 000100 31 32 33 34 7 100000 199 200 201 202 203 204 205 231 14 100001 205 206 207 208 209 210 211 238 21 100010 211 212 213 214 215 216 217 245 28 100011 217 218 219 220 221 222 223 252 35 100100 223 224 225 226 227 228 229 259 42 100101 229 230 231 232 233 234 235 266 49 100110 235 236 237 238 239 240 241 273 56 100111 241 242 243 244 245 246 247 280 000101 37 38 39 40 41 000110 43 44 45 46 47 48 000111 49 50 51 52 53 54 001000 55 56 57 58 59 60 61 63 101000 247 248 249 250 251 252 253 287 001001 61 62 63 64 65 66 67 70 101001 253 254 255 256 257 258 259 294 001010 67 68 69 70 71 72 73 77 101010 259 260 261 262 263 264 265 301 55 001011 73 74 75 76 77 78 79 84 101011 265 266 267 268 269 270 271 308 001100 79 80 81 82 83 84 85 91 101100 271 272 273 274 275 276 277 315 001101 85 86 87 88 89 90 91 98 101101 277 278 279 280 281 282 283 322 001110 91 92 93 94 95 96 97 105 101110 283 284 285 286 287 288 289 329 001111 97 98 99 100 101 102 103 112 101111 289 290 291 292 293 294 295 336 010000 103 104 105 106 107 108 109 119 110000 295 296 297 298 299 300 301 343 010001 109 110 111 112 113 114 115 126 110001 301 302 303 304 305 306 307 350 010010 115 116 117 118 119 120 121 133 110010 307 308 309 310 311 312 313 357 010011 121 122 123 124 125 126 127 140 110011 313 314 315 316 317 318 319 364 010100 127 128 129 130 131 132 133 147 110100 319 320 321 322 323 324 325 371 010101 133 134 135 136 137 138 139 154 110101 325 326 327 328 329 330 331 378 010110 139 140 141 142 143 144 145 161 110110 331 332 333 334 335 336 337 385 010111 145 146 147 148 149 150 151 168 110111 337 338 339 340 341 342 343 392 011000 151 152 153 154 155 156 157 175 111000 343 344 345 346 347 348 349 399 406 011001 157 158 159 160 161 162 163 182 111001 349 350 351 352 353 354 355 011010 163 164 165 166 167 168 169 189 111010 355 356 357 358 359 360 361 413 011011 169 170 171 172 173 174 175 196 111011 361 362 363 364 365 366 367 011100 175 176 177 178 179 180 181 203 111100 367 368 369 370 371 372 373 427 011101 181 182 183 184 185 186 187 210 111101 373 374 375 376 377 378 379 434 011110 187 188 189 190 191 192 193 217 111110 379 380 381 382 383 384 385 441 011111 193 194 195 196 197 199 224 111111 385 386 387 389 390 391 448 198 388 420 Notes: To use this table, find the desired modulus in the table. Follow the column up to find the A divider programming values. Follow the row to the left to find the M divider programming. Some feedback divisors can be achieved with two or three combinations of divider settings. Any are acceptable for use. The formula for the effective feedback modulus is: except when A=0, then: Under all circumstances: N =[(M +1) • 6] +A N=(M +1) • 7 A≤M 10 ICS1574B Absolute Maximum Ratings VDD, VDDO (measured to VSS) . . . . . . . . Digital Inputs . . . . . . . . . . . . . . . . . . . . . . . Digital Outputs . . . . . . . . . . . . . . . . . . . . . . Ambient Operating Temperature . . . . . . . Storage Temperature . . . . . . . . . . . . . . . . . Junction Temperature . . . . . . . . . . . . . . . . . Soldering Temperature . . . . . . . . . . . . . . . . 7.0 V VSS – 0.5 V to VDD +0.5V VSS – 0.5V to VDD O +0.5V – 55° C to +125° C – 65° C to +150° C 175° C 260° C Recommended Operating Conditions VDD, VDDO (measured to VSS) . . . . . . . . 4.75 to 5.25 V Operating Temperature (Ambient) . . . . . . 0 to +70°C DC Electrical Characteristics TTL-Compatible Inputs (DATCLK, DATA, HOLD, PCLKEN) PARAME T E R Input High Voltage Input Low Voltage Input High Current Input Low Current Input Capacitance Hysterisis (DATCLK input) S YMB OL VIH VIL I IH I IL CIN V HYS CONDI TI ONS VIH = VDD VIL = 0 . 0 VDD = 5 V MI N 2. 0 VSS – 0 . 5 — — — . 20 MAX V DD + 0 . 5 0. 8 10 200 8 . 60 UNI TS V V µA µA pF V XTAL1 Input (External Reference Frequency) PARAME T E R Input High Voltage Input Low Voltage S YMB OL V XH V XL CONDI TI ONS MI N 3. 75 VSS – 0 . 5 MAX V DD + 0 . 5 1. 25 UNI TS V V S YMB OL CONDI TI ONS MI N 2. 4 — MAX — 0. 4 UNI TS V V PCLK PARAME T E R Output High Voltage (IOH = 4.0mA) Output Low Voltage (IOL = 8.0mA) 11 ICS1574B AC Electrical Characteristics PARAME T E R VCO Frequency Crystal Frequency Crystal Oscillator Loading Capacitance XTAL1 High Time (when driven externally) XTAL1 Low Time (when driven externally) PLL Acquire Time (to within 1%) VDD Supply Current VDDO Supply Current S YMB OL F VCO FXTAL CPAR T XHI T XLO T LOCK I DD I DDO MI N 40 5 TYP MAX 400 20 20 8 8 500 15 20 t . b. d. t . b. d. UNI TS MHz MHz pF ns ns µs mA mA Digital Inputs DATA/HOLD ~Setup Time DATA/HOLD ~Hold Time DATCLK Pulse Width (Thi or Tlo) 10 10 20 ns ns ns Digital Output PCLK output rate 130 F P CLOCK 16-Pin Skinny SOIC Package Ordering Information ICS1574BM / ICS1574BEB Example: ICS 1574B M Package Type M = SOIC • Device Type EB = Evaluation Board Prefix ICS, AV = Standard Device • GSP = Genlock Device 12 MHz