CDC2536 3.3-V PHASE-LOCK LOOP CLOCK DRIVER WITH 3-STATE OUTPUTS SCAS377D – APRIL 1994 – REVISED OCTOBER 1998 D D D D D D D D D D D D D DB PACKAGE (TOP VIEW) Low Output Skew for Clock-Distribution and Clock-Generation Applications Operates at 3.3-V VCC Distributes One Clock Input to Six Outputs One Select Input Configures Three Outputs to Operate at One-Half or Double the Input Frequency No External RC Network Required On-Chip Series Damping Resistors External Feedback Pin (FBIN) Is Used to Synchronize the Outputs to the Clock Input Application for Synchronous DRAM, High-Speed Microprocessor TTL-Compatible Inputs and Outputs Outputs Drive 50-Ω Parallel-Terminated Transmission Lines State-of-the-Art EPIC-ΙΙB BiCMOS Design Significantly Reduces Power Dissipation Distributed VCC and Ground Pins Reduce Switching Noise Packaged in Plastic 28-Pin Shrink Small-Outline Package AVCC AGND CLKIN SEL OE GND 1Y1 VCC GND 1Y2 VCC GND 1Y3 VCC 1 28 2 27 3 26 4 25 5 24 6 23 7 22 8 21 9 20 10 19 11 18 12 17 13 16 14 15 AVCC AGND FBIN TEST CLR VCC 2Y1 GND VCC 2Y2 GND VCC 2Y3 GND description The CDC2536 is a high-performance, low-skew, low-jitter clock driver. It uses a phase-lock loop (PLL) to precisely align, in both frequency and phase, the clock output signals to the clock input (CLKIN) signal. It is specifically designed for use with synchronous DRAMs and popular microprocessors operating at speeds from 50 MHz to 100 MHz or down to 25 MHz on outputs configured as half-frequency outputs. The CDC2536 operates at 3.3-V VCC and is designed to drive a 50-W transmission line. The CDC2536 also provides on-chip series-damping resistors, eliminating the need for external termination components. The feedback (FBIN) input is used to synchronize the output clocks in frequency and phase to the input clock (CLKIN). One of the six output clocks must be fed back to FBIN for the PLL to maintain synchronization between CLKIN and the outputs. The output used as the feedback pin is synchronized to the same frequency as CLKIN. The Y outputs can be configured to switch in phase and at the same frequency as CLKIN. The select (SEL) input configures three Y outputs to operate at one-half or double the CLKIN frequency, depending on which pin is fed back to FBIN (see Tables 1 and 2). All output signal duty cycles are adjusted to 50% independent of the duty cycle at the input clock. Output-enable (OE) is provided for output control. When OE is high, the outputs are in the high-impedance state. When OE is low, the outputs are active. TEST is used for factory testing of the device and can be use to bypass the PLL. TEST should be strapped to GND for normal operation. Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. EPIC-ΙΙB is a trademark of Texas Instruments Incorporated. Copyright 1998, Texas Instruments Incorporated PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 1 CDC2536 3.3-V PHASE-LOCK LOOP CLOCK DRIVER WITH 3-STATE OUTPUTS SCAS377D – APRIL 1994 – REVISED OCTOBER 1998 description (continued) Unlike many products containing PLLs, the CDC2536 does not require external RC networks. The loop filter for the PLL is included on-chip, minimizing component count, board space, and cost. Because it is based on PLL circuitry, the CDC2536 requires a stabilization time to achieve phase lock of the feedback signal to the reference signal. This stabilization time is required following power up and application of a fixed-frequency, fixed-phase signal at CLKIN, as well as following any changes to the PLL reference or feedback signals. Such changes occur upon change of SEL, enabling the PLL via TEST, and upon enable of all outputs via OE. The CDC2536 is characterized for operation from 0°C to 70°C. detailed description of output configurations The voltage-controlled oscillator (VCO) used in the CDC2536 has a frequency range of 100 MHz to 200 MHz, twice the operating frequency of the CDC2536 outputs. The output of the VCO is divided by two and by four to provide reference frequencies with a 50% duty cycle of one-half and one-fourth the VCO frequency. SEL determines which of the two signals is buffered to each bank of device outputs. One device output must be externally wired to FBIN to complete the PLL. The VCO operates such that the frequency of the output matches that of CLKIN. In the case that a VCO/2 output is wired to FBIN, the VCO must operate at twice the CLKIN frequency resulting in device outputs that operate at either the same or one-half the CLKIN frequency. If a VCO/4 output is wired to FBIN, the device outputs operate at the same or twice the CLKIN frequency. output configuration A Output configuration A is valid when any output configured as a 1× frequency output in Table 1 is fed back to FBIN. The input frequency range for CLKIN is 50 MHz to 100 MHz when using output configuration A. Outputs configured as 1/2× outputs operate at half the CLKIN frequency, while outputs configured as 1× outputs operate at the same frequency as CLKIN. Table 1. Output Configuration A INPUT OUTPUTS SEL 1/2× FREQUENCY 1× FREQUENCY L None All H 1Yn 2Yn NOTE: n = 1, 2, 3 output configuration B Output configuration B is valid when any output configured as a 1× frequency output in Table 2 is fed back to FBIN. The input frequency range for CLKIN is 25 MHz to 50 MHz when using output configuration B. Outputs configured as 1× outputs operate at the CLKIN frequency, while outputs configured as 2× outputs operate at double the frequency of CLKIN. Table 2. Output Configuration B INPUT OUTPUTS SEL 1× FREQUENCY 2× FREQUENCY H 1Yn 2Yn L All None NOTE: n = 1, 2, 3 2 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 CDC2536 3.3-V PHASE-LOCK LOOP CLOCK DRIVER WITH 3-STATE OUTPUTS SCAS377D – APRIL 1994 – REVISED OCTOBER 1998 functional block diagram OE 5 24 CLR FBIN 26 ÎÎÎÎÎÎÎ ÁÁÁ ÎÎÎÎÎÎÎ ÁÁÁ B ÁÁÁÁÁÁ ÎÎÎÎÎÎÎ ÁÁÁ ÎÎÎÎÎÎÎ ÎÎÎÎÎÎÎ Phase-Lock Loop 3 CLKIN TEST SEL 25 2 ÁÁÁ B ÁÁÁ ÁÁÁ 2 4 7 10 13 22 19 16 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 1Y1 1Y2 1Y3 2Y1 2Y2 2Y3 3 CDC2536 3.3-V PHASE-LOCK LOOP CLOCK DRIVER WITH 3-STATE OUTPUTS SCAS377D – APRIL 1994 – REVISED OCTOBER 1998 Terminal Functions TERMINAL NAME I/O DESCRIPTION CLKIN 3 I Clock input. CLKIN provides the clock signal to be distributed by the CDC2536 clock-driver circuit. CLKIN provides the reference signal to the integrated PLL that generates the clock output signals. CLKIN must have a fixed frequency and fixed phase for the phase-lock loop to obtain phase lock. Once the circuit is powered up and a valid CLKIN signal is applied, a stabilization time is required for the PLL to phase lock the feedback signal to its reference signal. CLR 24 I CLR is used for testing purposes only. FBIN 26 I Feedback input. FBIN provides the feedback signal to the internal PLL. FBIN must be hardwired to one of the six clock outputs to provide frequency and phase lock. The internal PLL adjusts the output clocks to obtain zero phase delay between the FBIN and differential CLKIN inputs. OE 5 I Output enable. OE is the output enable for all outputs. When OE is low, all outputs are enabled. When OE is high, all outputs are in the high-impedance state. Since the feedback signal for the PLL is taken directly from an output, placing the outputs in the high-impedance state interrupts the feedback loop; therefore, when a high-to-low transition occurs at OE, enabling the output buffers, a stabilization time is required before the PLL obtains phase lock. SEL 4 I Output configuration select. SEL selects the output configuration for each output bank (e.g. 1×, 1/2×, or 2×). (see Tables 1 and 2). TEST 25 I TEST is used to bypass the PLL circuitry for factory testing of the device. When TEST is low, all outputs operate using the PLL circuitry. When TEST is high, the outputs are placed in a test mode that bypasses the PLL circuitry. TEST should be grounded for normal operation. O These outputs are configured by SEL to transmit one-half or one-fourth the frequency of the VCO. The relationship between the CLKIN frequency and the output frequency is dependent on SEL. The duty cycle of the Y output signals is nominally 50%, independent of the duty cycle of the CLKIN signal. Each output has an internal series resistor to dampen transmission-line effects and improve the signal integrity at the load. O These outputs transmit one-half the frequency of the VCO. The relationship between the CLKIN frequency and the output frequency is dependent on the frequency of the output being fed back to FBIN. The duty cycle of the Y output signals is nominally 50%, independent of the duty cycle of the CLKIN signal. Each output has an internal series resistor to dampen transmission-line effects and improve the signal integrity at the load. 1Y1 – 1Y3 2Y1 – 2Y3 4 NO. 7, 10, 13 22, 19, 16 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 CDC2536 3.3-V PHASE-LOCK LOOP CLOCK DRIVER WITH 3-STATE OUTPUTS SCAS377D – APRIL 1994 – REVISED OCTOBER 1998 absolute maximum ratings over operating free-air temperature range (unless otherwise noted)† Supply voltage range, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 0.5 V to 4.6 V Input voltage range, VI (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 0.5 V to 7 V Voltage range applied to any output in the high state or power-off state, VO (see Note 1) . . . – 0.5 V to 5.5 V Current into any output in the low state, IO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 mA Input clamp current, IIK (VI < 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 20 mA Output clamp current, IOK (VO < 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 50 mA Maximum power dissipation at TA = 55°C (in still air) (see Note 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.68 W Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 65°C to 150°C † 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 under “recommended operating conditions” is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. NOTES: 1. The input and output negative-voltage ratings may be exceeded if the input and output clamp-current ratings are observed. 2. The maximum package power dissipation is calculated using a junction temperature of 150°C and a board trace length of 75 mils. For more information, refer to the Package Thermal Considerations application note in the 1994 ABT Advanced BiCMOS Technology Data Book, literature number SCBD002B. recommended operating conditions (see Note 3) MIN MAX 3.6 UNIT VCC VIH Supply voltage 3 High-level input voltage 2 VIL VI Low-level input voltage 5.5 V IOH IOL High-level output current – 12 mA Low-level output current 12 mA 70 °C V 0.8 Input voltage 0 TA Operating free-air temperature NOTE 3: Unused inputs must be held high or low to prevent them from floating. 0 V V electrical characteristics over recommended operating free-air temperature range (unless otherwise noted) PARAMETER VIK VOH VOL II IOZH IOZL ICC Ci TA = 25°C MIN MAX TEST CONDITIONS VCC = 3 V, VCC = MIN to MAX‡, II = –18 mA IOH = – 100 µA VCC = 3 V, VCC = 3 V, IOH = – 12 mA IOL = 100 µA VCC = 3 V, VCC = 0 or MAX‡, IOL = 12 mA VI = 3.6 V VCC = 3.6 V, VCC = 3.6 V, VI = VCC or GND VO = 3 V VCC = 3.6 V, VO = 0 VCC = 3.6 3 6 V, V VI = VCC or GND IO = 0 0, –1.2 VCC – 0.2 2 0.8 ±10 ±1 POST OFFICE BOX 655303 µA 10 µA µA 2 Outputs low 2 Outputs disabled 2 • DALLAS, TEXAS 75265 V – 10 Outputs high Co ‡ For conditions shown as MIN or MAX, use the appropriate value specified under recommended operating conditions. V V 0.2 VI = VCC or GND VO = VCC or GND UNIT mA 6 pF 9 pF 5 CDC2536 3.3-V PHASE-LOCK LOOP CLOCK DRIVER WITH 3-STATE OUTPUTS SCAS377D – APRIL 1994 – REVISED OCTOBER 1998 timing requirements over recommended ranges of supply voltage and operating free-air temperature fclock l k Clock frequency MIN MAX When VCO is operating at four times the CLKIN frequency 25 50 When VCO is operating at double the CLKIN frequency 50 100 40% 60% Duty cycle, CLKIN Stabilization time† After SEL 50 After OE↓ 50 After power up 50 UNIT MHz µs After CLKIN 50 † Time required for the integrated PLL circuit to obtain phase lock of its feedback signal to its reference signal. For phase lock to be obtained, a fixed-frequency, fixed-phase reference signal must be present at CLKIN. Until phase lock is obtained, the specifications for propagation delay and skew parameters given in the switching characteristics table are not applicable. switching characteristics over recommended ranges of supply voltage and operating free-air temperature, CL = 15 pF (see Note 4 and Figures 1, 2 and 3) FROM (INPUT) PARAMETER TO (OUTPUT) MIN Y 45% 55% CLKIN↑ Y↑ –500 +500 ps CLKIN↑ Y↑ 200 ps 0.5 ns 1 ns 1.4 ns fmax Duty cycle MAX 100 tphase error‡ tjitter (RMS) tsk(o)‡ UNIT MHz tsk(pr)‡ tr tf 1.4 ns ‡ The propagation delay, tphase error, is dependent on the feedback path from any output to FBIN. The tphase error, tsk(o), and tsk(pr) specfications are only valid for equal loading of all outputs. NOTE 4: The specifications for parameters in this table are applicable only after any appropriate stabilization time has elapsed. PARAMETER MEASUREMENT INFORMATION 3V Input 1.5 V 1.5 V 0V tphase error From Output Under Test CL = 15pF (see Note A) 500 W Output 2V 0.8 V tr LOAD CIRCUIT FOR OUTPUTS VOH 2V 1.5 V 0.8 V VOL tf VOLTAGE WAVEFORMS PROPAGATION DELAY TIMES NOTES: A. CL includes probe and jig capacitance. B. All input pulses are supplied by generators having the following characteristics: PRR ≤ 100 MHz, ZO = 50 Ω, tr ≤ 2.5 ns, tf ≤ 2.5 ns. C. The outputs are measured one at a time with one transition per measurement. Figure 1. Load Circuit and Voltage Waveforms 6 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 CDC2536 3.3-V PHASE-LOCK LOOP CLOCK DRIVER WITH 3-STATE OUTPUTS SCAS377D – APRIL 1994 – REVISED OCTOBER 1998 PARAMETER MEASUREMENT INFORMATION CLKIN tphase error 1 Outputs Operating at 1/2 CLKIN Frequency tphase error 2 tphase error 3 Outputs Operating at CLKIN Frequency tphase error 4 tphase error 7 tphase error 5 tphase error 8 tphase error 6 tphase error 9 NOTES: A. Output skew, tsk(o), is calculated as the greater of: – The difference between the fastest and slowest of tphase error n (n = 1, 2, . . . 6) – The difference between the fastest and slowest of tphase error n (n = 7, 8, 9) B. Process skew, tsk(pr), is calculated as the greater of: – The difference between the maximum and minimum tphase error n (n = 1, 2, . . . 6) across multiple devices under identical operating conditions – The difference between the maximum and minimum tphase error n (n = 7, 8, 9) across multiple devices under identical operating conditions Figure 2. Waveforms for Calculations of tsk(o) and tsk(pr) POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 7 CDC2536 3.3-V PHASE-LOCK LOOP CLOCK DRIVER WITH 3-STATE OUTPUTS SCAS377D – APRIL 1994 – REVISED OCTOBER 1998 PARAMETER MEASUREMENT INFORMATION CLKIN tphase error 10 Outputs Operating at CLKIN Frequency tphase error 11 tphase error 12 tphase error 13 Outputs Operating at 2X CLKIN Frequency tphase error 14 tphase error 15 NOTES: A. Output skew, tsk(o), is calculated as the greater of:. – The difference between the fastest and slowest of tphase error n (n = 10, 11, . . . 15) B. Process skew, tsk(pr), is calculated as the greater of: – The difference between the maximum and minimum tphase error n (n = 10, 11, . . . 15) across multiple devices under identical operating conditions. Figure 3. Waveforms for Calculation of tsk(o) and tsk(pr) 8 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 CDC2536 3.3-V PHASE-LOCK LOOP CLOCK DRIVER WITH 3-STATE OUTPUTS SCAS377D – APRIL 1994 – REVISED OCTOBER 1998 MECHANICAL INFORMATION DB (R-PDSO-G**) PLASTIC SMALL-OUTLINE PACKAGE 28 PIN SHOWN 0,38 0,22 0,65 28 0,15 M 15 0,15 NOM 8,20 7,40 5,60 5,00 Gage Plane 1 14 0,25 A 0°– 8° 1,03 0,63 Seating Plane 2,00 MAX 0,10 0,05 MIN PINS ** 8 14 16 20 24 28 30 38 A MAX 3,30 6,50 6,50 7,50 8,50 10,50 10,50 12,90 A MIN 2,70 5,90 5,90 6,90 7,90 9,90 9,90 12,30 DIM 4040065 / C 10/95 NOTES: A. B. C. D. All linear dimensions are in millimeters. This drawing is subject to change without notice. Body dimensions do not include mold flash or protrusion not to exceed 0,15. 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