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| Integrated Circuit Systems, Inc. ICS90C65 Dual Voltage Video/Memory Clock Generator Introduction The Integrated Circuit Systems ICS90C65 is a dual clock generator for VGA applications. It simultaneously generates two clocks. One clock is for the video memory, and the other is the video dot clock. The ICS90C65 has been specifically designed to serve the portable PC market with operation at either 3.3V or 5V with a comprehensive power-saving shut-down mode. This data sheet supplies sales order information, a functional overview, signal pin details, a block diagram, AC/DC characteristics, timing diagrams, and package mechanical information. Features * * * * * * * * * * Specified for dual voltage operation (VDD=3.3V or 5V), but operates continuously from 3.0V to 5.25V Designed to be powered-down for extended battery life Backward compatibility to the ICS90C64 and ICS90C63 Dual Clock generator for the IBM-compatible Western Digital Imaging Video Graphics Array (VGA) LSI devices, and 8514/A chip sets Integral loop filter components, reduce cost and phase jitter Generates fifteen video clock frequencies (including 25.175 and 28.322 MHz) derived from a 14.318 MHz system clock reference frequency On-chip generation of eight memory clock frequencies Video clock is selectable among the 15 internally generated clocks and one external clock CMOS technology Available in 20-pin PLCC, SOIC and DIP packages Description The Integrated Circuit Systems Video Graphics Array Clock Generator (ICS90C65) is capable of producing different output frequencies under firmware control. The video output frequency is derived from a 14.318 MHz system clock available in IBM PC/XT/AT and Personal System/2 computers. It is designed to work with Western Digital Imaging Video Graphics Array and 8514/A devices to optimize video subsystem performance. The video dot clock output may be one of 15 internallygenerated frequencies or one external input. The selection of the video dot clock frequency is done through four inputs. * * * * VSEL0 VSEL1 VSEL2 VSEL3 VSEL0 and VSEL1 are latched by the SELEN signal. VSEL2 and VSEL3 are used as direct inputs to the VCLK selection. Table 1-1 is the truth table for VCLK selection. The input and truth table have been designed to allow a direct connection to one of the many Western Digital Imaging VGA controllers or 8514/A chip sets. The MCLK output is one of eight internally-generated frequencies as shown in Table 1-2. The various VCLK and MCLK frequencies are derived from the 14.318 MHz input frequency. The VCLKE and MCLKE input can tristate the VCLK and MCLK outputs to facilitate board level testing. Note:ICS90C65N (DIP) pin-out is identical to ICS90C65M (SOIC) pin-out. 90C65ARevA111095 ICS90C65 ICS90C65 VGA Interface The ICS90C65 has two system interfaces: System Bus and VGA Controller, as well as other programmable inputs. Figure 1 shows how the Integrated Circuit Systems's VGA Clock ICS90C65 is connected to a VGA controller. Western Digital Imaging VGA controllers normally have a status bit that indicates to the VGA controller that it is working with a clock chip. When working with a clock chip the VGA controller changes t wo of i ts cl ock inputs to outputs. They are theVCLK1/VCSLD/VCSEL and VCLK2/VCSEL/VCSELH outputs and they are used to select the required video frequency. When the power-down capabilities are used, the control signal for PWRDN is normally held in one of a group of latches. If the power-down function is not to be used, PWRDN must be tied to VDD, otherwise the internal pull-down will place the chip in the power-down mode. WD90C26 pull-up at reset and PR15(5)=0 AMD(3) LATCH VCS VCSEL VCKIN MCLK ICS90C65 SD2 SD3 VSEL0 VSEL1 VSEL2 SELEN 14.318 MHz CLK1 MC PWRDN VCLK Figure 1 2 ICS90C65 System Bus Inputs The system bus inputs are: * * * CLKI VSEL0 VSEL1 User-Definable Inputs The user definable inputs are: * * * * * EXTCLK VLCKE, MCLKE MSELO-2 VSEL2, VSEL3 PWRDN The ICS90C65 uses the system bus 14.318 MHz clock as a reference to generate all its frequencies for both video and memory clocks. Data lines D2 and D3 are commonly used as inputs to VSEL0 and VSEL1 for video frequency selection. EXTCLK is an additional input that may be internally routed to the VCLK output. This additional input is useful for supporting modes that require frequencies not provided by the ICS90C65 or for use during board test. VCLKE and MCLKE are the output enable signals for VCLK and MCLK. When low the respective output is tristated. MSEL0-2 are the memory clock (MCLK) select lines. Table 1-2 shows how MCLK frequencies are selected. All signals in this group have internal pull-up resistors. VSEL2 and VSEL3 are video clock (VCLK) select lines that can select additional VCLK frequencies. See Table 1-1. VSEL2 and VSEL3 have internal pull-ups. PWRDN can place the ICS90C65 in a power-down mode which drops its supply current requirement below 1 microamp. When placed in this mode, the digital inputs may be either high or low or floating without causing an increase in the ICS90C65 supply current. The PWRDN pin must be low (It has an internal pull-down.) in order to place the device in its low power state. The output pins (VCLK and MCLK) are driven high by the ICS90C65 when it is in its low power state. If CLKI is being driven by an external source, it may be driven low or high without a power penalty. If CLKI is at an intermediate voltage (VSS+0.5 < VIN Inputs from VGA Controller The VGA controller input to the ICS90C65 is: * SELEN The ICS90C65 is programmed to generate different video clock frequencies using the inputs of VSEL0, VSEL1, VSEL2, and VSEL3. The signals VSEL2 and VSEL3 may be supplied by the VGA controller as is the case in Western Digital Imaging VGA controllers. The inputs VSEL0-1 are latched with the signal SELEN. The SELEN input should be an active low pulse. This active low pulse is generated in Western Digital Imaging VGA controllers during I/O writes to internal register 3C2h. Note: Only VSEL0 and VSEL1 are latched with signal SELEN. Outputs to VGA Controller The outputs from the ICS90C65 to the VGA controller are: * * MCLK VCLK MCLK and VCLK are the two clock outputs to the VGA controller. Analog Filters The analog filters are integral to the ICS90C65 device. No external components are required. This feature reduces PC board space requirements and component costs. Phase-jitter is reduced as externally-generated noise cannot easily influence the phase-locked loop filter. 3 ICS90C65 Power Considerations The ICS90C65 product requires an AVDD supply free of fast rise time transients. This requirement may be met in several ways and is highly dependent on the characteristics of the host system. A VGA adapter card is unique in that it must function in an unknown environment. +5 volt power quality is dependent not only on the quality of the power supply resident in the host system, but also on the other cards plugged into the host's backplane. Power supply noise ranges from fair to terrible. As the VGA adapter manufacturer has no control over this, he must assume the worst. The best solution is to create a clean +5 volts by deriving it from the +12 volt supply by using a zener diode and dropping resistor. A 470 Ohm resistor and 5.1 volt Zener diode are the least costly way to accomplish this. A .047 to .1 microfarad bypass capacitor tied from AVDD to AvSS insures good high- frequency decoupling of this point. Laptop and notebook computers have entirely different problems with power. Typically they have no +12 volt supply; however, they are much quieter electrically. Because the designer has complete control of the system architecture, he can place sensitive components and systems such as the RAMDAC and Dual Video/Memory Clock away from DRAM and other noise-generating components. Most systems provide power that is clean enough to allow for jitter-free Dual Video/Memory Clock performance if the +5 volt supply is decoupled with a resistor and 22 microfarad Tantalum capacitor. Digital inputs that are desired to be held at a static logical high level should not be tied to +5 volts as this may result in excessive current drain through the ESD protection diode. The internal pull-up resistors will adequately keep these inputs high. 4 ICS90C65 Pin Descriptions The following table provides the pin descriptions for the 20-pin ICS90C65 packages. PIN NUMBER 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 PIN SYMBOL CLKI MSEL2 EXTCLK VSEL1 VSEL0 SELEN VSEL2 VSEL3 MSEL0 DVSS MSEL1 MCLK PWRDN MCLKE AVDD AVSS NC VCLKE VCLK DVDD TYPE IN IN IN IN IN IN IN IN IN IN OUT IN IN IN OUT - DESCRIPTION Reference input clock from system. Select input for MCLK selection. External clock input for an additional frequency. Control input for VCLK selection. Control input for VCLK selection. Strobe for latching VSEL(0,1) (low enable). Control input for VCLK selection. Control input for VCLK selection. Select input for MCLK selection. Ground for Digital Circuit. Select input for MCLK selection. Memory Clock Output. Power Down Control. Enable input for MCLK output (high enables output). Power supply for analog circuit. Ground for analog circuit. No connection. Enable input for VCLK output (high enables output). Video Clock Output. Power supply for Digital Circuit. Note: CLKI, EXTCLK,VSEL0, VSEL1,VSEL2, VSEL3, SELEN, MSEL0, MSEL1, MSEL2, VCLKE, and MCLKE - input pins have internal pull-up resistors. PWRDN has an internal pull-down resistor. 5 ICS90C65 Absolute Maximum Ratings Ambient Temperature under bias Storage temperature Voltage on all inputs and outputs with respect to VSS 0C to 70C -40C to 125C 0.3 to 7 volts Standard Test Conditions The characteristics below apply for the following standard test conditions, unless otherwise noted. All voltages are referenced to VSS (OV Ground). Positive current flows into the referenced pin. Operating Temperature range Power supply voltage 0C to 70C 3.0 to 5.25 volts Note: 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. AC Timing Characteristics The following notes apply to all of the parameters presented in this section: 1. 2. 3. 4. 5. 6. 7. REFCLK = 14.318 MHz TC = 1/FC All units are in nanoseconds (ns). Maximum jitter is within a range of 30 s after triggering on a 400 MHz scope. Rise and fall time is between 0.8 and 2.0 VDC unless otherwise stated. Output pin loading = 15pF Duty cycle is measured at VDD/2 unless otherwise stated. SYMBOL Tpw Tsu Thd Tr Tf - Tr Tf - MIN MAX STROBE TIMING Strobe Pulse Width 20 Setup Time Data to Strobe 20 Hold Time Data to Strobe 10 MCLK and VCLK TIMINGS @ 5.0V 2 Rise Time 2 Fall Time 0.5 Frequency Error 135 Maximum Frequency 20 Propagation Delay for Pass Through Frequency 15 Output Enable to Tristate (into and out of) time MCLK and VCLK TIMINGS @ 3.3V 3 Rise Time 3 Fall Time .5 Frequency Error 110 Maximum Frequency 30 Propagation Delay for Pass Through Frequency 20 Output Enable to Tristate (into and out of) time PARAMETER NOTES Duty Cycle 40% min. to 60% max. % MHz ns ns Duty Cycle 40% min. to 60% max. % MHz ns ns 6 ICS90C65 DC Characteristics at 5 Volts VDD SYMBOL VDD VIL VIH IIH VOL VOH IDD RUP Cin Cout IPN RDN PARAMETER Operating Voltage Range Input Low Voltage Input High Voltage Input Leakage Current Output Low Voltage Output High Voltage Supply Current Internal Pull-up Resistors Input Pin Capacitance Output Pin Capacitance Power-down Supply Current Internal Pull-down Equivalent MIN 4.75 VSS 2.0 2.4 50 20 MAX 5.25 0.8 VDD 10 0.4 30 8 12 1.0 UNITS V V V A V V mA K ohms pF pF A K ohms CONDITIONS VDD = 5V VDD = 5V VIN = VCC IOL = 8.0 mA IOH = 8.0 mA VDD = 5V VIN = 0.0V FC = 1 MHz FC = 1 MHz VDD=3.3V VIN=VDD=5V DC Characteristics at 3.3 Volts VDD SYMBOL VDD VIL VIH IIH VOL VOH IDD RUP Cin Cout IPN RDN PARAMETER Operating Voltage Range Input Low Voltage Input High Voltage Input Leakage Current Output Low Voltage Output High Voltage Supply Current Internal Pull-up Resistors Input Pin Capacitance Output Pin Capacitance Power-down Supply Current Internal Pull-down Equivalent MIN 3.0 VSS 2.0 2.4 100 50 MAX 3.6 0.8 VDD 10 0.4 20 8 12 1.0 UNITS V V V A V V mA K ohms pF pF A K ohms CONDITIONS VDD = 3.3V VDD = 3.3V Vin = VDD IOL = 3.0 mA IOH = 3.0 mA VDD = 3.3V VIN = 0.0V FC = 1 MHz FC = 1 MHz VDD =3.3V VIN =VDD =3.3V 7 ICS90C65 ICS90C65 Timing 8 ICS90C65 Table 1-1 VCLK SELECTION VSEL 3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 VCLK FREQUENCY (MHz) Pattern 951 30.0 77.25 EXTCLK 80.0 31.5 36.0 75.0 50.0 40.0 50.0 32.0 44.9 25.175 28.322 65.0 36.0 Table 1-2 MCLK SELECTION MSEL 2 0 0 0 0 1 1 1 1 1 0 0 1 1 0 0 1 1 0 0 1 0 1 0 1 0 1 MCLK FREQUENCIES (MHz) Pattern 951 33.0 49.218 60.0 30.5 41.612 37.5 36.0 44.296 9 ICS90C65 20-Pin DIP Package 20-Pin SOIC Package PLCC Package Ordering Information ICS90C65N or ICS90C65M or ICS90C65V Example: ICS XXXX- XXX N Package Type N=DIP (Plastic) M=SOIC V=PLCC Pattern Number (2 or 3 digit number for parts with ROM code patterns) Device Type (consists of 3-6 digit numbers) Prefix ICS, AV=Standard Device; GSP=Genlock Device 10 |
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