82C284 Clock Generator and Ready Interface for 80C286 Processors March 1997 Features Description • Generates System Clock for 80C286 Processors The Intersil 82C284 is a clock generator/driver which provides clock signals for 80C286 processors and support components. It also contains logic to supply READY to the CPU from either asynchronous or synchronous sources and synchronous RESET from an asynchronous input with hysteresis. • Generates System Reset Output from Schmitt Trigger Input - Improved Hysteresis • Uses Crystal or External Signal for Frequency Source • Dynamically Switchable between Two Input Frequencies • Provides Local READY and MULTIBUS READY Ordering Information PART NUMBER Synchronization • Static CMOS Technology • Single +5V Power Supply • Available in 18 Lead CerDIP Package Pinout TEMP. RANGE PACKAGE PKG. NO. CD82C284-12 0oC to +70oC 18 Ld CERDIP F18.3 ID82C284-10 -40oC to +85oC 18 Ld CERDIP F18.3 ID82C284-12 -40oC to +85oC 18 Ld CERDIP F18.3 Functional Diagram 82C284 (CERDIP) TOP VIEW RESET ARDY 1 18 VCC RESET RES SRDY 2 17 ARDYEN SRDYEN 3 16 S1 READY 4 15 S0 X1 EFI 5 14 NC X2 F/C 6 13 PCLK X1 7 12 RESET X2 8 11 RES F/C GND 9 10 CLK ARDYEN SYNCHRONIZER XTAL OSC CLK MUX EFI ARDY SRDYEN SRDY S1 S0 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. http://www.intersil.com or 407-727-9207 | Copyright © Intersil Corporation 1999 is a patented Intel bus. MULTIBUS 1 SYNCHRONIZER READY LOGIC READY PCLK GENERATOR File Number PCLK 2966.1 82C284 Pin Description The following pin function descriptions are for the 82C284 clock generator. PIN SYMBOL NUMBER TYPE DESCRIPTION CLK 10 O SYSTEM CLOCK: the signal used by the processor and support devices which must be synchronous with the processor. The frequency of the CLK output has twice the desired internal processor clock frequency. CLK can drive both TTL and CMOS level inputs. F/C 6 I FREQUENCY/CRYSTAL SELECT: this pin selects the source for the CLK output. When there is a LOW level on this input, the internal crystal oscillator drives CLK. When there is a HIGH level on F/C, the EFI input drives the CLK input. This pin can be dynamically switched, which allows changing the processor CLK frequency while running for low-power operation, etc. X1, X2 7, 8 I CRYSTAL IN: the pin stop which parallel resonant, fundamental mode crystal is attached for the internal oscillator. When F/C is LOW, the internal oscillator will drive the CLK output at the crystal frequency. The crystal frequency must be twice the desired internal processor clock frequency. EFI 5 I EXTERNAL FREQUENCY IN: drives CLK when the F/C input is HIGH. The EFI input frequency must be twice the desired internal processor clock frequency. PCLK 13 O PERIPHERAL CLOCK: the output which provides a 50% duty cycle clock with one-half the frequency of CLK. PCLK will be in phase with the internal processor clock following the first bus cycle after the processor has been reset. ARDYEN 17 I ASYNCHRONOUS READY ENABLE: an active LOW input which qualifies the ARDY input. ARDYEN selects ARDY as the source of READY for the current bus cycle. Inputs to ARDYEN may be applied asynchronously to CLK. Setup and hold times are given to assure a guaranteed response to synchronous outputs. ARDY 1 I ASYNCHRONOUS READY: an active LOW input used to terminate the current bus cycle. The ARDY input is qualified by ARDYEN. Inputs to ARDY may be applied asynchronously to CLK. Setup and hold times are given to assure a guaranteed response to synchronous outputs. SRDYEN 3 I SYNCHRONOUS READY ENABLE: an active LOW input which qualifies SRDY. SRDYEN selects SRDY as the source for READY to the CPU for the current bus cycle. Setup and hold time must be satisfied for proper operation. SRDY 2 I SYNCHRONOUS READY: an active LOW input used to terminate the current bus cycle. The SRDY input is qualified by the SRDYEN input. Setup and hold time must be satisfied for proper operation. READY 4 O READY: an active LOW output which signals to the processor that the current bus cycle is to be completed. The SRDY SRDYEN, ARDY, ARDYEN, S1, S0, and RES inputs control READY as explained later in the READY generator section. READY is an open drain output requiring an external pull-up resistor. S0, S1 15,16 I STATUS: these inputs prepare the 82C284 for a subsequent bus cycle. S0 and S1 synchronize PCLK to the internal processor clock and control READY. Setup and hold times must be satisfied for proper operation RESET 12 O RESET: an active HIGH output which is derived from the RES input RESET is used to force the system into an initial state. When RESET is active, READY will be active (LOW). RES 11 I RESET IN: an active LOW input which generates the system reset signal (RESET). Signals to RES may be applied asynchronously to CLK. A Schmitt trigger input is provided on RES, so that an RC circuit can be used to provide a time delay. Setup and hold times are given to assure a guaranteed response to synchronous inputs. VCC 18 SYSTEM POWER: The +5V Power Supply Pin. A 0.1µF capacitor between VCC and GND is recommended for decoupling. GND 9 SYSTEM GROUND: 0V 2 82C284 Functional Description 2) When switching CLK frequency sources, there is a maximum transition latency of 2.5 clock cycles of the frequency being switched to, from the time CLK freezes low, until CLK restarts at the new frequency (see Waveforms). 3) The maximum latency from the time F/C is dynamically switched, to the time CLK freezes low, is 4 CLK cycles (see Waveforms). Introduction The 82C284 generates the clock, ready, and reset signals required for 80C286 processors and support components. The 82C284 is packaged in an 18-pin DIP and contains a crystal controlled oscillator, clock generator, peripheral clock generator, MULTIBUS® ready synchronization logic, and system reset generation logic. The following steps describe the sequence of events that transpire when F/C is dynamically switched: Clock Generator A) The CLK output provides the basic timing control for an 80C286 system. CLK has output characteristics sufficient to drive CMOS devices. CLK is generated by either an internal crystal oscillator, or an external source as selected by the F/C input pin. When F/C is LOW, the crystal oscillator drives the CLK output. When F/C is HIGH, the EFI input drives the CLK output. 1) The state of F/C is sampled when both CLK and PCLK are high until a change is detected. 2) On the second following falling edge of PCLK, CLK is frozen low. 3) CLK restarts at the crystal frequency on the rising edge of Xl, after the second falling edge of X1. The F/C pin on the Intersil 82C284 is dynamically switchable. This allows the CLK frequency to the processor to be changed from one frequency to another in a running system. With this feature, a system can be designed which operates at maximum speed when needed, and then dynamically switched to a lower frequency to implement a low-power mode. The lower frequency can be anything down to, but excluding, DC. The following 3 conditions apply when dynamically switching the F/C pin (see Figure 1): 1) B) φ2 F/C switched from low (using the crystal input Xl) to high (using the EFI input - see Figure 1B). 1) The state of F/C is sampled when both CLK and PCLK are high until a change is detected. 2) On the second following falling edge of PCLK, CLK is frozen low. The CLK is stretched in the low portion of the φ2 phase of its cycle during transition from one CLK frequency to the other (see Waveforms). φ1 F/C switched from high (using EFI input) to low (using the crystal input X1 - see Figure 1A). 3) CLK restarts at the EFI input frequency on the falling edge of EFl after the second rising edge of EFI. φ1 φ2 φ1 φ2 1 CLK 2 PCLK F/C X1 3 FIGURE 1A. F/C SWITCHED FROM HIGH (USING EFI INPUT) TO LOW (USING THE CRYSTAL INPUT X1) 3 82C284 1 CLK φ1 φ2 φ1 φ2 φ1 φ2 2 PCLK F/C 3 EFI FIGURE 1B. F/C SWITCHED FROM LOW (USING THE CRYSTAL INPUT X1) TO HIGH (USING THE EFI INPUT) FIGURE 1. DYNAMICALLY SWITCHING THE F/C PIN The 82C284 provides a second clock output, PCLK, for peripheral devices. PCLK is CLK divided by two. PCLK has a duty cycle of 50% and CMOS output drive characteristics. PCLK is normally synchronized to the internal processor clock. CLK Termination Due to the CLK output having a very fast rise and fall time, it is recommended to properly terminate the CLK line at frequencies above 10MHz to avoid signal reflections and ringing. Termination is accomplished by inserting a small resistor (typically 10-74Ω) in series with the output, as shown in Figure 2. This is known as series termination. The resistor value plus the circuit output impedance (approximately 25Ω) should be made equal to the impedance of the transmission line. After reset, the PCLK signal may be out of phase with the internal processor clock. The S1 and S0 signals of the first bus cycle are used to synchronize PCLK to the internal processor clock. The phase of the PCLK output changes by extending its HIGH time beyond one system clock (see waveforms). PCLK is forced HIGH whenever either S0 or S1 were active (LOW) for the two previous CLK cycles. PCLK continues to oscillate when both S0 and S1 are HIGH. CLK OUT Z Since the phase of the internal processor clock will not change except during reset, the phase of PCLK will not change except during the first bus cycle after reset. RO ≈ 25 Oscillator Reset Operation The reset logic provides the RESET output to force the system into a known, initial state. When the RES input is active (LOW), the RESET output becomes active (HIGH), RES is synchronized internally at the falling edge of CLK before generating the RESET output (see waveforms). Synchronization of the RES input introduces a one or two CLK delay before affecting the RESET Output. At power up, a system does not have a stable VCC and CLK. To prevent spurious activity, RES should be asserted until VCC and CLK stabilize at their operating values. 80C286 processors and support components also require their RESET inputs be HIGH a minimum of 16 CLK cycles. An RC network, as shown in Figure 3, will keep RES LOW long enough to satisfy both needs. TABLE 1. 82C284 CRYSTAL LOADING CAPACITANCE VALUES C2 CAPACITANCE (PIN 8) 1MHz to 8MHz 60pF 40pF 8MHz to 20MHz 25pF 15pF 20MHz to 25MHz 15pF 15pF CLOSELY PLACED LOADS FIGURE 2. SERIES TERMINATION X1 and X2 are the oscillator crystal connections. For stable operation of the oscillator, two loading capacitors are recommended, as shown in Table 1. The sum of the board capacitance and loading capacitance should equal the values shown. It is advisable to limit stray board capacitances (not including the effect of the loading capacitors or crystal capacitance) to less than 10pF between the X1 and X2 pins. Decouple VCC and GND as close to the 82C284 as possible with a 0.1µF polycarbonate capacitor. Cl CAPACITANCE (PIN 7) CLOSELY PLACED LOADS TRANSMISSION LINE Z The oscillator circuit of the 82C284 is a linear Pierce oscillator which requires an external parallel resonant, fundamental mode, crystal. The output of the oscillator is internally buffered. The crystal frequency chosen should be twice the required internal processor clock frequency. The crystal should have a typical load capacitance of 32pF. CRYSTAL FREQUENCY R A Schmitt trigger input with hysteresis on RES assures a single transition of RESET with an RC circuit on RES. The hysteresis separates the input voltage level at which the circuit output switches from HIGH to LOW from the input voltage level at which the circuit output switches from LOW to HIGH. The RES HIGH to LOW input transition voltage is lower than the RES 4 82C284 LOW to HIGH input transition voltage. As long as the slope of the RES input voltage remains in the same direction (increasing or decreasing) around the RES input transition voltage, the RESET output will make a single transition. 7 10 X1 8 VCC CLK CLK VCC X2 82C284 C1 80C286 CPU OR SUPPORT COMPONENT 4 1N914 10kΩ F/C 11 47Ω RES + READY 6 82C284 VCC 18 READY VCC DECOUPLING CAPACITOR 10µF FIGURE 4. RECOMMENDED CRYSTAL AND READY CONDITIONS Figure 5 illustrates the operation of SRDY and SRDYEN. These inputs are sampled on the falling edge of CLK when S1 and S0 are inactive and PCLK is HIGH. READY is forced active when both SRDY and SRDYEN are sampled as LOW. FIGURE 3. TYPICAL RC RES TIMING CIRCUIT Ready Operation The 82C284 accepts two ready sources for the system ready signal which terminates the current bus cycle. Either a synchronous (SRDY) or asynchronous ready (ARDY) source may be used. Each ready input has an enable (SRDYEN and ARDYEN) for selecting the type of ready source required to terminate the current bus cycle. An address decoder would normally select one of the enable inputs. Figure 6 shows the operation of ARDY and ARDYEN These inputs are sampled by an internal synchronizer at each falling edge of CLK. The output of the synchronizer is then sampled when PCLK is HIGH. If the synchronizer resolved both the ARDY and ARDYEN as active, the SRDY and SRDYEN inputs are ignored. Either ARDY or ARDYEN must be HIGH at the end of TS, therefore, at least one wait state is required when using the ARDY and ARDYEN inputs as a basis for generating READY. READY is enabled (LOW), if either SRDY + SRDYEN = 0 or ARDY + ARDYEN = 0 when sampled by the 82C284 READY generation logic. READY will remain active for at least two CLK cycles. READY remains active until either S1 or S0 are sampled LOW, or the ready inputs are sampled as inactive. The READY output has an open-drain driver allowing other ready circuits to be wired with it, as shown in Figure 4. The READY signal of an 80C286 system requires an external pull-up resistor. To force the READY signal inactive (HIGH) at the start of a bus cycle, the READY output floats when either S1 or S0 are sampled LOW at the falling edge of CLK. Two system clock periods are allowed for the pull-up resistor to pull the READY signal to VlH . When RESET is active, READY is forced active one CLK later (see Waveforms). 5 82C284 TS TC TC T1 CLK PCLK S1 * S0 VIH ARDYEN SRDYEN + SRDY READY FIGURE 5. SYNCHRONOUS READY OPERATION TS TC TC CLK PCLK S1 * S0 VIH SRDYEN ARDY + ARDYEN READY FIGURE 6. ASYNCHRONOUS READY OPERATION 6 T1 82C284 Absolute Maximum Ratings Thermal Information Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +8.0V Input, Output or I/O Voltage Applied. . . . . GND -0.5V to VCC +0.5V Storage Temperature Range . . . . . . . . . . . . . . . . . -65oC to +150oC Thermal Resistance θJA (oC/W) θJC (oC/W) CERDIP Package . . . . . . . . . . . . . . . . 80 20 Gate Count . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 Gates Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +175oC Lead Temperature (Soldering, 10s). . . . . . . . . . . . . . . . . . . . +300oC ESD Classification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Class 2 Operating Conditions Operating Temperature Range C82C284. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0oC to +70oC I82C284 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40oC to +85oC Operating Supply Voltage . . . . . . . . . . . . . . . . . . . . . +4.5V to +5.5V EFI Rise Time (from 0.8V to 3.2V) . . . . . . . . . . . . . . . . . . 8ns (Max) EFI Fall Time (from 3.2 to 0.8V) . . . . . . . . . . . . . . . . . . . . 8ns (Max) CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. DC Electrical Specifications SYMBOL TA = 0oC to +70oC (CD82C284); VCC = 5V ± 10% TA = -40oC to +85oC (ID82C284) PARAMETER MIN MAX UNITS TEST CONDITIONS VIL Input LOW Voltage - 0.8 V VCC = 4.5V VIH Input HIGH Voltage 2.2 - V VCC = 5.5V VIHC EFI, F/C Input HIGH Voltage 3.2 - V VCC = 5.5V VIHR RES HIGH Voltage VCC-0.8 - V VCC = 5.5V VHYS RES Input Hysteresis 0.5 - V VCC = 5.5V VOL RESET, PCLK Output LOW Voltage - 0.4 V IOL = 5mA, VCC = 4.5V, Note 2 VOH RESET, PCLK Output HIGH Voltage VCC-0.4 - V IOH = -1mA, VCC = 4.5V, Note 2 VOLR READY Output LOW Voltage - 0.4 V IOL = 10mA, VCC = 4.5V, Note 2 VOLC CLK Output LOW Voltage - 0.4 V IOL = 5mA, VCC = 4.5V, Note 2 VOHC CLK Output HIGH Voltage VCC-0.4 - V IOH = -5mA, VCC = 4.5V, Note 2 -10 10 µA VIN = VCC or GND, VCC = 5.5V - 60 mA 82C284-12 (Note 1) - 48 mA 82C284-10 (Note 1) IIL ICCOP Input Leakage Current Active Power Supply Current NOTES: 1. ICCOP measured at 10MHz for 82C284-10 and at 12.5MHz for the 82C284-12. VIN = GND or VCC, VCC = 5.5V outputs unloaded. 2. Interchanging of force and sense conditions is permitted. AC Electrical Specifications TA = 0oC to +70oC (CD82C284); VCC = 5V ±10% TA = -40oC to +85oC (lD82C284) AC Timings are Referenced to 0.8V and 2.0V Points of the Signals as Illustrated in Waveforms, Unless Otherwise Noted. 10MHz SYMBOL PARAMETER 12.5MHz MIN MAX MIN MAX UNIT TEST CONDITIONS t1 EFl LOW Time 20 - 16 - ns At VCC/2 (Note 8) t2 EFI HIGH Time 20 - 20 - ns At VCC/2 (Note 8) 5A Status Setup Time for Status Going Active 20 - 18 - ns 5B Status Setup Time for Status Going Inactive 20 - 16 - ns 7 82C284 AC Electrical Specifications TA = 0oC to +70oC (CD82C284); VCC = 5V ±10% (Continued) TA = -40oC to +85oC (lD82C284) AC Timings are Referenced to 0.8V and 2.0V Points of the Signals as Illustrated in Waveforms, Unless Otherwise Noted. 10MHz SYMBOL PARAMETER 12.5MHz MIN MAX MIN MAX UNIT ns TEST CONDITIONS t6 Status Hold Time 1 - 1 - t7 F/C Setup Time 15 - 15 - t8 F/C Hold Time 15 - 15 - t9 SRDY or SRDYEN Setup Time 15 - 15 - ns t10 SRDY or SRDYEN Hold Time 2 - 2 - ns t11 ARDY or ARDYEN Setup Time 5 - 5 - ns (Note 3) t12 ARDY or ARDYEN Hold Time 30 - 25 - ns (Note 3) t13 RES Setup Time 20 - 18 - ns (Notes 3, 7) t14 RES Hold Time 10 - 8 - ns (Notes 3, 7) t16 CLK Period 50 - 40 - t17 CLK LOW Time 12 - 11 - ns (Notes 2, 6) t18 CLK HIGH Time 16 - 13 - ns (Notes 2, 6) t21 READY Inactive Delay 5 - 5 - ns At 0.8V (Note 4), Test Condition 2 t22 READY Active Delay - 24 - 18 ns At 0.8V (Note 4) t23 PCLK Delay - 20 - 16 ns CL = 75pF, Test Condition 1 t24 RESET Delay - 27 - 26 ns CL = 75pF, Test Condition 3 t25 PCLK LOW Time t16 -10 - t16 -10 - na CL = 75pF (Note 5) t26 PCLK HIGH Time t16 -10 - t16 -10 - ns CL= 75pF (Note 5) NOTES: 1. VCC = 4.5V and 5.5V unless otherwise specified. CLK loading: CL = 100pF. 2. With the internal crystal oscillator using recommended crystal and capacitive loading; or with the EFI input meeting specifications t1 and t2. The recommended crystal loading for CLK frequencies of 8MHz to 20MHz are 25pF from pin X1 to ground, and 15pF from pin X2 to ground; for CLK frequencies from 20MHz to 25MHz the recommended loading is 15pF from pin X1 to GND. These recommended values are +5pF and include all stray capacitance. Decouple VCC and GND as close to the 82C284 as possible. 3. This is an asynchronous input. This specification is given for testing purposes only, to assure recognition at a specific CLK edge. 4. The pull-up resistor value for the READY pin is 620Ω with the rated 150pF load. 5. t16 refers to any allowable CLK period. 6. When using a crystal with the recommended capacitive loading, CLK output HIGH and LOW times are guaranteed to meet 80C286 requirements. 7. Measured from 1.0V on the CLK to 0.8V on the RES waveform for RES waveform for RES active and to 4.2V on the RES waveform for RES inactive. 8. Input test waveform characteristics: VIL = 0V, VlH = 4.5V. UNTESTED SPECIFICATIONS 10MHz SYMBOL PARAMETER 12.5MHz MIN MAX MIN MAX UNITS CONDlTIONS (NOTE 1) CIN Input Capacitance - 10 - 10 pF FREQ = 1MHz, All measurements are referenced to device GND, TA = +25oC t15A EFI HIGH to CLK LOW Delay - 30 - 25 ns (Note 2) t15B EFI LOW to CLK HIGH Delay - 35 - 30 ns (Note 3) 8 82C284 UNTESTED SPECIFICATIONS (Continued) 10MHz SYMBOL PARAMETER 12.5MHz MIN MAX MIN MAX UNITS CONDlTIONS (NOTE 1) t19 CLK Rise Time - 8 - 8 ns 1.0V to 3.6V, CL = 100pF t20 CLK Fall Time - 8 - 8 ns 3.6V to 1.0V, CL = 100pF t27 X1 HIGH to CLK - 35 - 30 ns (Note 4) NOTES: 1. The parameters listed in this table are controlled via design or, process parameters and are not directly tested. These parameters are characterized upon initial design and after major process and/or design changes. 2. Measured from 3.2V on the EFI waveform to 1.0V on the CLK. 3. Measured from 0.8V on the EFI waveform to 3.6V on the CLK. 4. Measured from 3.6V on the X1 input to 3.6V on the CLK. AC Specifications EFI INPUT AC Test Condition 3.8V 3.2V 0.8V VCC 0.4V RL tDELAY (MAX) VCC - 0.4V 3.6V 1.0V CLK OUTPUT DEVICE OUTPUT 3.6V 1.0V 0.4V CL tSETUP tHOLD F/C INPUT RES INPUT 3.8V 3.2V 3.2V 0.8V 0.8V FIGURE 8. 0.4V VCC - 0.4V VCC - 0.8V 0.8V 0.8V 0.4V 2.4 OTHER DEVICE INPUT 2.0V 2.0V 0.8V 0.8V 0.4V tDELAY (MAX) tDELAY (MIN) DEVICE OUTPUT 2.0V 0.8V FIGURE 7. A.C. DRIVE, SETUP, HOLD AND DELAY TIME MEASUREMENT POINTS 9 TEST CONDITION RL CL 1 750Ω 75pF 2 620Ω 150pF 3 ∞ 75pF 82C284 Waveforms t2 t1 t16 EFI t15B t19 t18 CLK t20 t17 t15A NOTE: 1. The EFI input LOW and HIGH times as shown are required to guarantee the CLK LOW and HIGH times shown. FIGURE 9. CLK AS A FUNCTION OF EFI t16 CLK SEE NOTE t14 t13 t14 t13 RES t24 t24 RESET DEPENDS ON STATE OF PREVIOUS RES t22 t21 READY NOTE: 1. This is an asynchronous input. The setup and hold times shown are required to guarantee the response shown. FIGURE 10. RESET AND READY TIMING AS A FUNCTION OF RES WITH S1, S0, ARDY + ARDYEN, AND SRDY + SRDYEN HIGH TS φ1 φ2 TC φ1 φ2 CLK t6 t5B t6 S1 • S0 t23 t23 t5A t26 t25 PCLK UNDEFINED IF THIS IS FIRST BUS CYCLE SRDY + SRDYEN t9 t10 NOTE 1 t12 t11 t11 t12 ARDY + ARDYEN t21 READY t21 t22 NOTE 2 NOTES: 1. This is an asynchronous input. The setup and hold times shown are required to guarantee the response shown. 2. If SRDY + SRDYEN or ARDYEN are active before and/or during the first bus cycle after RESET, READY may not be deasserted until the falling edge of φ2 of TS. FIGURE 11. READY AND PCLK TIMING WITH RES HIGH 10 82C284 Waveforms (Continued) φ1 φ2 φ1 φ2 φ1 φ2 CLK PCLK t7 t8 F/C t27 X1 CLK φ1 φ2 φ1 φ2 φ1 φ2 PCLK F/C t7 t15B t8 EFI NOTE: 1. This is an asynchronous input. The setup and hold times are required to guarantee the response shown. FIGURE 12. CLK AS A FUNCTION OF F/C, PCLK, X1, AND EFI DURING DYNAMIC FREQUENCY SWITCHING All Intersil semiconductor products are manufactured, assembled and tested under ISO9000 quality systems certification. Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries. 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