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| Integrated Circuit Systems, Inc. ICS9161A Dual Programmable Graphics Frequency Generator General Description The ICS9161A is a fully programmable graphics clock generator. It can generate user-specified clock frequencies using an externally generated input reference or a single crystal. The output frequency is programmed by entering a 24-bit digital word through the serial port. Two fully userprogrammable phase-locked loops are offered in a single package. One PLL is designed to drive the memory clock, while the second drives the video clock. The outputs may be changed on-the-fly to any desired frequency between 390 kHz and 120 MHz. The ICS9161A is ideally suited for any design where multiple or varying frequencies are required. This part is ideal for graphics applications. It generates low jitter, high speed pixel clocks. It can be used to replace multiple, expensive high speed crystal oscillators. The flexibility of the device allows it to generate non-standard graphics clocks. The ICS9161A is also ideal in disk drives. It can generate zone clocks for constant density recording schemes. The low profile, 16-pin SOIC or PDIP package and low jitter outputs are especially attractive in board space critical disk drives. The leader in the area of multiple output clocks on a single chip, ICS has been shipping graphics frequency generators since October, 1990, and is constantly improving the phaselocked loop. The ICS9161A incorporates a patented fourth generation PLL that offers the best jitter performance available. Features * * * * * * * * * * * Pin-for-pin and function compatible with ICD2061A Dual programmable graphics clock generator Memory and video clocks are individually programmable on-the-fly Ideal for designs where multiple or varying frequencies are required Increased frequency resolution from optional predivide by 2 on the M counter Output enable feature available for tristating outputs Independent clock outputs range from 390 kHz to 120 MHz for VDD >4.75V Power-down capabilities Low power, high speed 0.8 CMOS technology Glitch-free transitions Available in 16-pin, 300-mil SOIC or PDIP package Block Diagram EXTCLK EXTSEL D14-D20 7 REF fREF DIVIDE (M/) D4-D10 7 24 24 DECODE LOGIC ADDRESS 3 DATA 21 CONTROL REG 21 21 21 VCLK (D0-D20) VCO DIVIDE (N/) D0-D3 4 D11-D13 3 CMOS OUTPUT DRIVER X1 X2 XTAL OSC VCO VCO OUTPUT DIVIDER R=1,2,4,8,16 32,64,128 MUX VCLK SEL0-CLK SEL1-DATA REGISTERS 3-TO-1 MUX 21 Pscale P= 2 or 4 OE 21 MCLK (D0-D20) D14-D20 7 REF DIVIDE (M/) D4-D10 7 D0-D3 4 D11-D13 3 INIT1 INIT2 INIT ROM VCO VCO OUTPUT DIVIDER R=1,2,4,8,16 32,64,128 CMOS OUTPUT DRIVER MCLK POR PD VCO DIVIDE (N/) Pscale P= 2 9161-A RevG 10/04/00 9161 ICS reserves the right to make changes in the device data identified in this publication without further notice. ICS advises its customers to obtain the latest version of all device data to verify that any information being relied upon by the customer is current and accurate. ICS9161A Pin Configuration 16-Pin 300- mil SOIC or PDIP Pin Descriptions PIN NUMBER 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 PIN NAME SEL0-CLK SEL1-DATA AVDD OE GND X1 X2 MCLK VCLK ERROUT# EXTCLK INIT0 VDD INIT1 EXTSEL PD# TYPE IN IN PWR IN PWR IN OUT OUT OUT OUT IN IN PWR IN IN IN DESCRIPTION Clock input in serial programming mode. Clock select pin in operating mode. Has internal pull-down to GND. Data input in serial programming mode. Clock select pin in operating mode. Has internal pull-down to GND. Power. Tristates outputs when low. Has internal pull-up to VDD. Ground. Crystal input. This input includes XTAL load capacitance and feedback bias for the crystal. Crystal output which includes internal XTAL load capacitance. Memory clock output. Video clock output. Output low signals an error in the serially programmed word. External clock input. Has internal pull-up to VDD. Selects initial power-up conditions, LSB. Has internal pull-down to GND. Power. Selects initial power-up conditions, MSB. Has internal pull-down to GND. Selects external clock input (EXTCLK) as VCLK output. Has internal pull-up to VDD. Power-down pin, active low. Has internal pull-up to VDD. 2 ICS9161A Register Definitions The register file consists of the following six registers: Register Addressing Address (A2 - A0) 000 001 010 011 100 110 Register REG0 REG1 REG2 MREG PWRDWN CNTL REG Definition Video Clock Register 1 Video Clock Register 2 Video Clock Register 3 Memory Register Divisor for Power-down mode Control Register As seen in the VCLK Selection table, OE acts to tristate the output. The PD# pin forces the VCLK signal high while powering down the part. The EXTCLK pin will only be multiplexed in when EXTSEL and SEL0 are logic 0 and SEL1 is a logic 1. The memory clock outputs are controlled by PD# and OE as follows: MCLK Selection OE 0 1 1 PD# x 1 0 MCLK Tristate MREG PWRDWN The ICS9161A places the three video clock registers and the memory clock register in a known state upon power-up. The registers are initialized based on the state of the INIT1 and INIT0 pins at application of power to the device. The INIT pins must ramp up with VDD if a logical 1 on either pin is required. These input pins are internally pulled down and will default to a logical 0 if left unconnected. The registers are initialized as follows: Register Initialization INIT1 0 0 1 1 INIT0 0 1 0 1 MREG 32.500 40.000 50.350 56.644 REG0 25.175 25.175 40.000 40.000 REG1 28.322 28.322 28.322 50.350 REG2 28.322 28.322 28.322 50.350 The Clock Select pins SEL0 and SEL1 have two purposes. In serial programming mode, these pins act as the clock and data pins. New data bits come in on SEL1 and these bits are clocked in by a signal on SEL0. While these pins are acquiring new information, the VCLK signal remains unchanged. When SEL0 and SEL1 are acting as register selects, a time-out interval is required to determine whether the user is selecting a new register or wants to program the part. During this initial time-out, the VCLK signal remains at its previous frequency. At the end of this time-out interval, a new register is selected. A second time-out interval is required to allow the VCO to settle to its new value. During this period of time, typically 5ms, the input reference signal is multiplexed to the VCLK signal. When MCLK or the active VCLK register is being reprogrammed, then the reference signal is multiplexed glitchfree to the output during the first time-out interval. A second time-Register out interval is also required to allow the VCO to settle. During this period, the reference signal is multiplexed to the appropriate output signal. Register Selection When the ICS9161A is operating, the video clock output is controlled with a combination of the SEL0, SEL1, PD# and OE pins. The video clock is also multiplexed to an external clock (EXTCLK) which can be selected with the EXTSEL pin. The VCLK Selection Table shows how VCLK is selected. VCLK Selection OE 0 1 1 1 1 1 1 PD# x 0 1 1 1 1 1 EXTSEL x x x x 0 1 x SEL1 SEL0 x x 0 0 1 1 1 x x 0 1 0 x 1 VCLK Tristate Forced High REG0 REG1 EXTCLK REG2 REG2 3 ICS9161A Control Register Definitions The control register allows the user to adjust various internal options. The register is defined as follows: Bit Bit Name Default Value Description This bit determines which power-down mode the PD# pin will implement. Power-down mode 1, C5=0, forces the MCLK signals to be a function of the power-down register. Power-down mode 2, C5=1, turns off the crystal and disables all outputs. This bit determines which clock is multiplexed to VCLK during frequency changes. C4=0 multiplexes the reference frequency to the VCLK output. C4=1 multiplexes MCLK to the VCLK output for applications where the graphics controller cannot run as slow as fREF. This bit determines the length of the time-out interval. The time-out interval is derived from the MCLK VCO. If this VCO is programmed to certain extremes, the time-out interval may be too short. C3=0, normal time-out. C3=1, doubled time-out interval. Reserved, must be set to 0. This bit adjusts the duty cycle. C1=0 causes a 1ns decrease in output high time. C1=1 causes no adjustment. If the load capacitance is high, the adjustment can bring the duty cycle closer to 50%. Reserved, must be set to 0. Acts on register 2. NS2=0 prescales the N counter by 2. NS2=1 prescales the P counter value to 4. Acts on register 1. NS1=0 prescales the N counter by 2. NS1=1 prescales the P counter value to 4. Acts on register 0. NS1=0 prescales the N counter by 2. NS0=1 prescales the P counter value to 4. 21 C5 0 20 C4 0 19 18 17 16 15 14 13 C3 C2 C1 C0 NS2 NS1 NS0 0 0 1 0 0 0 0 4 ICS9161A Serial Programming Architecture The pins SEL0 and SEL1 perform the dual functions of selecting registers and serial programming. In serial programming mode, SEL0 acts as a clock pin while SEL1 acts as the data pin. The ICS9161A-01 may not be serially programmed when in power-down mode. In order to program a particular register, an unlocking sequence must occur. The unlocking sequence is detailed in the following timing diagram: Since the VCLK registers are selected by the SEL0 and SEL1 pins, and since any change in their state may affect the output frequency, new data input on the selection bits is only permitted to pass through the decode logic after the watchdog timer has timed out. This delay of SEL0 or SEL1 data permits a serial program cycle to occur without affecting the current register selection. Serial Data Register The serial data is clocked into the serial data register in the order described in Figure 1 below (Serial Data Timing). The serial data is sent as follows: An individual data bit is sampled on the rising edge of CLK. The complement of the data bit must be sampled on the previous falling edge of CLK. The setup and hold time requirements must be met on both CLK edges. For specifics on timing, see the timing diagrams on pages 10, 11 and 12. The unlock sequence consists of at least five low-to-high transitions of CLK while data is high, followed immediately by a single low-to-high transition while data is low. Following this unlock sequence, data can be loaded into the serial data register. This programming must include the start bit, shown in Figure 1. Following any transition of CLK or DATA, the watchdog timer is reset and begins counting. The watchdog timer ensures that successive rising edges of CLK and DATA do not violate the time-out specification of 2ms. If a time-out occurs, the lock mechanism is reset and the data in the serial data register is ignored. The bits are shifted in this order: a start bit, 21 data bits, 3 address bits (which designate the desired register), and a stop bit. A total of 24 bits must always be loaded into the serial data register or an error is issued. Following the entry of the last data bit, a stop bit or load command is issued by bringing DATA high and toggling CLK high-to-low and low-to-high. The unlocking mechanism then resets itself following the load. Only after a time-out period are the SEL0 and SEL1 pins allowed to return to a register selection function. Figure 1: Serial Data Timing 5 ICS9161A The serial data register is exactly 24 bits long, enough to accept the data being sent. The stop bit acts as a load command that passes the contents of the Serial Data Register into the register indicated by the three address bits. If a stop bit is not received after the serial register is full, and more data is sent, all data in the register is ignored and an error issued. If correct data is received, then the unlocking mechanism re-arms, all data in the serial data register is ignored, and an error is issued. The equations used to determine the oscillator frequency are: N=N' + 3 M=M' + 2 FVCO=Prescale * N/M * FREF where 3 M 129 and 4 N 130 and prescale=2 or 4, as set in the control register (Where N is the VCO divider & M is the reference divider) The value of FVCO must remain between 50 MHz and 120 MHz. As a result, for output frequencies below 50 MHz, FVCO must be brought into range. To achieve this, an output divisor is selected by setting the values of the Mux Field (R) as follows: Output Divisor R 000 001 010 011 100 101 110 111 Divisor 1 2 4 8 16 32 64 128 ERROUT# Operation Any error in programming the ICS9161A is signaled by ERROUT#. When the pin goes low, an error has been detected. It stays low until the next unlock sequence. The signal is invoked for any of the following errors: incorrect start bit, incorrect data encoding, incorrect length of data word, and incorrect stop bit. Programming the ICS9161A The ICS9161A has a wide operating range, but it is recommended that it is operated within the following limits: 3.15V< VDD <5.25V 1 MHz I VCLK FVCO Turn off VCLK Mux MCLK to VLCK MCLK FVCO 50 - 120 MHz 50 - 120 MHz The frequency of the programmable oscillator FVCO is determined by the following fields: Field Index (I) N counter value (N') Mux (R) M counter value (M') # of Bits 4 7 3 7 1110 1111 Where the least significant bit is the last bit of M and the most significant bit is the first bit of I. When the index field is set to 1111, VCLK is turned off and both channels run from the same MCLK VCO. This is done in an effort to reduce jitter, which may increase when VCOs run at 2n multiples of one another. If the two outputs have to be multiples of one another, it is best to mux MCLK over to the output of the VCLK VCO and to power-down the VCLK VCO. The multiplexed frequency will be divided down by the correct divisor (M) and output on VCLK. 6 ICS9161A Power Management Issues Power-down mode 1 The ICS9161A contains a mechanism to reduce the quiescent power when stand-by operation is desired. Power-down mode 1 is invoked by polling PD# low and having the proper CNTL register bit set to zero. In this mode, VCOs are shut down, the VCLK output is forced high, and the MCLK output is set to a user-defined low frequency value to refresh dynamic RAM. The power-down MCLK value is determined by the following equation: MCLKPD = FREF/(PWRDWN register divisor value) The power-down register divisor is determined according to the 4-bit word programmed into the PWRDWN register (see table below). Power-down mode 2 When there is no need for any output during power-down, an alternate mode is available which will completely shut down all outputs and the reference oscillator, but still preserves all register contents. Power-down mode 2 in invoked by first programming the power-down bit in the CNTL register and then pulling the PD# pin low. The PD# pin The PD# pin has a standard internal pull-up resistor during normal operation. When the chip goes into power-down mode 1 or 2, the normal pull-up resistor is dynamically switched to a weak pull-up, which reduces power consumption. If the PD# pin is allowed to float after it has been pulled down, the weak pull-up will bring the signal high and allow the device to resume operation. Power-Down Register Table PWRDWN bits P3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 P2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 P1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 P0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 PWRDWN Register Value 0 1 2 3 4 5 6 7 8 (default) 9 A B C D E F Power-down Divisor n/a 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 MCLKPD (fREF=14.31818) n/a 447.4 kHz 477.3 kHz 511.4 kHz 550.7 kHz 596.6 kHz 650.8 kHz 715.9 kHz 795.5 kHz 894.9 kHz 1.02 MHz 1.19 MHz 1.43 MHz 1.79 MHz 2.39 MHz 3.58 MHz 7 ICS9161A Absolute Maximum Ratings VDD referenced to GND ............................................... 7V Operating temperature under bias (TOPER) .................... 0C to 70C Storage temperature ...................................................... -40C to +150C Max. soldering temperature (10 sec) (TSOL) ................ +260C Voltage on I/O pins referenced to GND ........................ GND -0.5V to VDD +0.5V Junction temperature (Tj) .............................................. +125C Power dissipation ........................................................... 0.35 Watts Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect product reliability. Electrical Characteristics at 5.0V VDD = +5V 5%, 0C TAMBIENT +70C DC Characteristics PARAMETER High level input voltage Low level input voltage High level CMOS output voltage1 Low level output voltage1 Input high current Input low current Output leakage current Power supply current Power supply current (typical) Analog power supply current Power-down current (Mode 1) Power-down current (Mode 2) Input capacitance1 SYMBOL VIH VIL VOH VOL IIH IIL IOZ IDD IDD-TYP IADD IPD1 IPD2 CIN @60 MHz IOH=-4mA IOL=4mA VDD=VIH=5.25V for pulldowns VIL=0V for pull-ups (tristate) TEST CONDITIONS MIN 2.0 3.84 -250 -10 15 TYP 35 6 25 MAX 0.8 0.4 100 10 65 20 7.5 50 10 UNITS V V V V A A A mA mA mA mA A pF Note 1: Parameter is guaranteed by design and characterization. Not 100% tested in production. 8 ICS9161A Electrical Characteristics at 5.0V (continued) AC Characteristics DESCRIPTION Reference oscillator value2 1/fREF Duty cycle for the input oscillator defined as t1/tREF Output oscillator values Duty cycle for the output oscillators3 Rise time for the output oscillators into a 25pF load Fall time for the output oscillators into a 25pF load Old frequency output New frequency output Time clock output remains high while output muxes to reference frequency Interval for serial programming and for VCO changes to settle4 Time clock output remains high while output muxes to new frequency value Time for the output oscillators to go into tristate mode after OUTDIS-signal assertion Time for the output oscillators to recover from tristate mode after OUTDIS-signal goes high Time for power-down mode of operation to take effect Time for recovery from power-down mode to a valid CLK Time for MCLK to go high after PWRDWN is asserted high Delay of MCLK prior to fMCLK signal at output Clock period of serial clock Set-up time Hold time Load command NAME Reference frequency Reference period Input duty cycle Output clock periods Output duty cycle Rise times Fall times freq1 output freq2 output fREF mux time Time-out interval tfreq2muxtime SYMBOL fREF tREF t1 t2 t3 t4 t5 tfreq1 tfreq2 tA ttime-out tB MIN 1 16.6 25% 8.33 (120 MHz) 45% 0.5 tREF 2 0.5 tREF TYP 14.31818 69.8408 5 1.5 tREF MAX 60 1000 75% 2564 (390 kHz) 55% 3 3 1.5tREF 10 UNITS MHz ns ns ns ns ns ms ns Tristate t6 - 25 - ns CLK valid t7 - 12 - ns Power-down Power-up MCLKOUT high MCLKOUT delay t8 t9 t10 t11 tserclk tSU tHD tldcmd 0 0.5 tMCLK 2 * tREF 20 10 0 25 12 - tPWRDWN 1.5 tMCLK 2 t1+30 ns ns ns ns ms ns ns ns Notes: 1. Parameter guaranteed by design and characterization. Not 100% tested in production. 2. For reference frequencies other than 14.81818 MHz, the pre-loaded ROM frequencies will shift proportionally. 3. Duty cycle is measured at CMOS threshold levels. At 5 volts, VTH=2.5 volts. 4. If the interval is too short, see the time-out interval section in the control register definition. 9 ICS9161A Rise and Fall Times Tristated Timing 10 ICS9161A Selection Timing MCLK and Active VCLK Register Programming Timing 11 ICS9161A Soft Power-Down Timing (Mode 2) Serial Programming Timing 12 ICS9161A General Layout Precautions: 1) Use a ground plane on the top layer of the PCB in all areas not used by traces. 2) Make all power traces and vias as wide as possible to lower inductance. Notes: 1) All clock outputs should have series terminating resistor. Not shown in all places to improve readibility of diagram. 2) 47 ohm / 56pf RC termination should be used on all over 50MHz outputs. 3) Optional crystal load capacitors are recommended. Capacitor Values: C1, C2 : Crystal load values determined by user C3 : 100pF ceramic All unmarked capacitors are 0.01F ceramic Connections to VDD: 13 ICS9161A 16-Pin PDIP Package Ordering Information ICS9161A-01CN16 Example: ICS XXXX - PPP M X#W Lead Count & Package Width Lead Count=1, 2 or 3 digits W=.3" SOIC or .6" DIP; None=Standard Width Package Type N=DIP (Plastic) Pattern Number (2 or 3 digit number for parts with ROM code patterns, if applicable) Device Type (consists of 3 or 4 digit numbers) Prefix ICS, AV=Standard Device 14 ICS9161A LEAD COUNT DIMENSION L 16L 0.404 SOIC Package (wide body) Ordering Information ICS9161A-01CW16 Example: ICS XXXX - PPP M X#W Lead Count & Package Width Lead Count=1, 2 or 3 digits W=.3" SOIC or .6" DIP; None=Standard Width Package Type W=SOIC Pattern Number (2 or 3 digit number for parts with ROM code patterns, if applicable) Device Type (consists of 3 or 4 digit numbers) Prefix ICS, AV = Standard Device 15 ICS reserves the right to make changes in the device data identified in this publication without further notice. ICS advises its customers to obtain the latest version of all device data to verify that any information being relied upon by the customer is current and accurate. |
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