Sample & Buy Product Folder Support & Community Tools & Software Technical Documents CDCM1802 SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 CDCM1802 Clock Buffer With Programmable Divider, LVPECL I/O + Additional LVCMOS Output 1 Features 3 Description • The CDCM1802 clock driver distributes one pair of differential clock input to one LVPECL differential clock output pair, Y0 and Y0, and one single-ended LVCMOS output, Y1. It is specifically designed for driving 50-Ω transmission lines. The LVCMOS output is delayed by 1.6 ns over the PECL output stage to minimize noise impact during signal transitions. 1 • • • • • • • Distributes One Differential Clock Input to One LVPECL Differential Clock Output and One LVCMOS Single-Ended Output Programmable Output Divider for Both LVPECL and LVCMOS Outputs 1.6-ns Output Skew Between LVCMOS and LVPECL Transitions Minimizing Noise 3.3-V Power Supply (2.5-V Functional) Signaling Rate Up to 800-MHz LVPECL and 200-MHz LVCMOS Differential Input Stage for Wide Common-Mode Range Also Provides VBB Bias Voltage Output for Single-Ended Input Signals Receiver Input Threshold ±75 mV 16-Pin VQFN Package (3.00 mm × 3.00 mm) The CDCM1802 has two control pins, S0 and S1, to select different output mode settings. The S[1:0] pins are 3-level inputs. Additionally, an enable pin EN is provided to disable or enable all outputs simultaneously. The CDCM1802 is characterized for operation from −40°C to 85°C. For single-ended driver applications, the CDCM1802 provides a VBB output pin that can be directly connected to the unused input as a common-mode voltage reference. Device Information(1) 2 Applications • • • • PART NUMBER Networking and Data Communications Medical Imaging Portable Test and Measurement High-end A/V CDCM1802 PACKAGE VQFN (16) BODY SIZE (NOM) 3.00 mm × 3.00 mm (1) For all available packages, see the orderable addendum at the end of the data sheet. Application Example CDCM1802 250 MHz 125 MHz IN, IN Y0,Y0 RS0 = open S0 Setting for Mode 4: EN = VDD/2 S1 = 0 S0 = 1 RS1 = 0 S1 125 MHz Y1 REN = 60lQ EN 1 An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications, intellectual property matters and other important disclaimers. PRODUCTION DATA. CDCM1802 SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 www.ti.com Table of Contents 1 2 3 4 5 6 7 8 Features .................................................................. Applications ........................................................... Description ............................................................. Revision History..................................................... Pin Configuration and Functions ......................... Specifications......................................................... 1 1 1 2 3 4 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 6.10 6.11 6.12 4 4 4 4 5 6 6 6 7 7 7 8 Absolute Maximum Ratings ...................................... ESD Ratings ............................................................ Recommended Operating Conditions....................... Thermal Information .................................................. Electrical Characteristics........................................... Switching Characteristics .......................................... Jitter Characteristics.................................................. Supply Current Electrical Characteristics ................. Control Input Characteristics..................................... Timing Requirements ............................................. Bias Voltage VBB.................................................... Typical Characteristics ............................................ Parameter Measurement Information .................. 9 Detailed Description ............................................ 11 8.1 8.2 8.3 8.4 9 Overview ................................................................. Functional Block Diagram ....................................... Feature Description................................................. Device Functional Modes........................................ 11 11 11 11 Application and Implementation ........................ 15 9.1 Application Information............................................ 15 9.2 Typical Application ................................................. 17 10 Power Supply Recommendations ..................... 19 11 Layout................................................................... 19 11.1 Layout Guidelines ................................................. 19 11.2 Layout Example .................................................... 20 11.3 Thermal Considerations ........................................ 21 12 Device and Documentation Support ................. 22 12.1 12.2 12.3 12.4 12.5 12.6 Device Support...................................................... Documentation Support ....................................... Community Resources.......................................... Trademarks ........................................................... Electrostatic Discharge Caution ............................ Glossary ................................................................ 22 22 22 22 22 22 13 Mechanical, Packaging, and Orderable Information ........................................................... 22 4 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision A (July 2008) to Revision B • 2 Page Added ESD Ratings table, Thermal Information table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section. .................................... 1 Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 CDCM1802 www.ti.com SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 5 Pin Configuration and Functions 13 S0 S1 15 14 VSS EN 16 RGT Package 16-Pin VQFN Top View IN 3 10 Y0 VBB 4 9 8 Y0 VDD1 11 7 2 Y1 IN 6 VDD0 VSS 12 5 1 VSS VDDPECL VDD0 Pin Functions PIN NAME NO. I/O I (with 60-kΩ pullup) DESCRIPTION ENABLE. Enables or disables all outputs simultaneously; The EN pin offers three different configurations: tie to GND (logic 0), external 60-kΩ pulldown resistor (pull to VDD/2) or left floating (logic 1); EN = 1: outputs on according to S0 and S1 setting EN = VDD/2: outputs on according to S0 and S1 setting EN = 0; outputs Y[1:0] off (high-impedance); see Table 1 for details. EN 16 IN 2 IN 3 S0 13 I S1 15 I (with 60-kΩ pullup) Y1 7 O LVCMOS clock output. This output provides a copy of IN or a divided down copy of clock IN based on the selected mode of operation: S0, S1, and EN. Also, this output can be disabled by tying VDD1 to GND. Y0 10 Y0 11 O LVPECL LVPECL clock output. This output provides a copy of IN or a divided down copy of clock IN based on the selected mode of operation: S1, S0, and EN. If Y0 output is unused, the output can simply be left open to save power and minimize noise impact to Y1. VBB 4 O VDDPECL (1) 1 Supply Supply voltage PECL input + internal logic 9, 12 Supply PECL output supply voltage for output Y0; Y0 can be disabled by pulling VDD0 to GND. Caution: In this mode no voltage from outside may be forced because internal diodes could be forced in a forward direction. Thus, it is recommended to leave the output disconnected. 8 Supply Supply voltage CMOS output; The CMOS output can be disabled by pulling VDD1 to GND. Caution: In this mode no voltage from outside may be forced, because internal diodes could be forced in forward direction. Thus, it is recommended to leave Y1 unconnected, tied to GND, or terminated into GND. 5, 6, 14 Supply Device ground VDD0 VDD1 VSS (1) (1) Differential input clock. Input stage is sensitive and has a wide common mode range. Therefore, almost any type of differential signal can drive this input (LVPECL, LVDS, CML, HSTL). Since the input is high-impedance, it is recommended to terminate the PCB transmission line before the input (for example, with 100-Ω across input). The input can also I be driven by a single-ended signal, if the complementary input is tied to a dc reference Differential input voltage (for example, V /2). CC The inputs deploy an ESD structure protecting the inputs in case of an input voltage exceeding the rails by more than ≈0.7 V. Reverse biasing of the IC through this inputs is possible and must be prevented by limiting the input voltage < VDD. Select mode of operation. Defines the output configuration of Y0 and Y1. Each pin offers three different configurations: tied to GND (logic 0), external 60-kΩ pulldown resistor (pull to VDD/2) or left floating (logic 1); see Table 1 for details. Output bias voltage used to bias unused complementary input IN for single-ended input signals. The output voltage of VBB is VDD −1.3 V. When driving a load, the output current drive is limited to about 1.5 mA. VDD0, VDD1, and VDDPECL should have the same value. Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 3 CDCM1802 SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 www.ti.com 6 Specifications 6.1 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted) (1) MIN MAX UNIT VDD Supply voltage −0.3 3.8 V VI Input voltage −0.2 (VDD + 0.2) V VO Output voltage −0.2 (VDD + 0.2) V Yn, Yn, IOSD Differential short circuit current TJ Maximum junction temperature 125 125 °C Tstg Storage temperature −65 150 °C (1) Continuous Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. 6.2 ESD Ratings VALUE V(ESD) (1) (2) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1) ±3000 Charged-device model (CDM), per JEDEC specification JESD22C101 (2) ±1500 UNIT V JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process. 6.3 Recommended Operating Conditions over operating free-air temperature range (unless otherwise noted) VDD Supply voltage VDD Supply voltage (only functionality) TA Operating free-air temperature MIN NOM MAX 3 3.3 3.6 UNIT V 2.375 3.6 V –40 85 °C 6.4 Thermal Information CDCM1802 THERMAL METRIC (1) RGT (VQFN) UNIT 16 PINS RθJA Junction-to-ambient thermal resistance 48.4 °C/W RθJC(top) Junction-to-case (top) thermal resistance 66.9 °C/W RθJB Junction-to-board thermal resistance 22.5 °C/W ψJT Junction-to-top characterization parameter 1.7 °C/W ψJB Junction-to-board characterization parameter 22.5 °C/W RθJC(bot) Junction-to-case (bottom) thermal resistance 5.8 °C/W (1) 4 For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report, SPRA953. Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 CDCM1802 www.ti.com SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 6.5 Electrical Characteristics over recommended operating free-air temperature range (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT MHz LVPECL INPUT IN, IN fclk Input frequency 0 800 VCM High-level input common mode 1 VDD − 0.3 VIN Input voltage swing between IN and IN IIN Input current RIN Input impedance CI Input capacitance at IN, IN See (1) 500 1300 See (2) 150 1300 VI = VDD or 0 V ±10 300 V mV µA kΩ 1 pF LVPECL OUTPUT DRIVER Y0, Y0 fclk Output frequency (see Figure 3) VOH High-level output voltage VOL Low-level output voltage VO Output voltage swing between Y and Y (see Figure 3) IOZL Output 3-state IOZH CO Output capacitance LOAD Expected output load 0 800 Termination with 50 Ω to VDD − 2 V VDD − 1.18 VDD – 0.81 V Termination with 50 Ω to VDD − 2 V VDD − 1.98 VDD – 1.55 V Termination with 50 Ω to VDD − 2 V 500 mV VDD = 3.6 V, VO = 0 V VDD = 3.6 V, VO = VDD – 0.8 V VO = VDD or GND MHz 5 µA 10 µA 1 pF 50 Ω LVCMOS OUTPUT PARAMETER, Y1 Output frequency (3) (see Figure 4) fclk 0 VDD = min to max, IOH = −100 µA VOH High-level output voltage VDD = 3 V, IOH = −6 mA VDD = 3 V, IOH = −12 mA VOL Low-level output voltage 200 2.4 V 2 VDD = min to max, IOL = 100 µA 0.1 VDD = 3 V, IOL = 6 mA 0.5 VDD = 3 V, IOL = 12 mA 0.8 IOH High-level output current VDD = 3.3 V, VO = 1.65 V −29 IOL Low-level output current VDD = 3.3 V, VO = 1.65 V 37 IOZ High-impedance state output current VDD = 3.6 V, VO = VDD or 0 V CO Output capacitance VDD = 3.3 V Load Expected output loading (see Figure 9) (1) (2) (3) MHz VDD – 0.1 V mA mA ±5 µA 2 pF 10 pF Required to maintain AC specifications Required to maintain device functionality Operating the CDCM1802 LVCMOS output above the maximum frequency will not cause a malfunction to the device, but the Y1 output signal swing will not achieve enough signal swing to meet the output specification. Therefore, the CDCM1802 can be operated at higher frequencies, while the LVCMOS output Y1 becomes unusable. Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 5 CDCM1802 SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 www.ti.com 6.6 Switching Characteristics over operating free-air temperature range (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT LVPECL OUTPUT DRIVER Y0, Y0 tDuty Output duty cycle distortion (1) Crossing point-to-crossing point distortion tsk(pp) Part-to-part skew Any Y0 (see Note A in Figure 7) tr/tf Rise and fall time 20% to 80% of VOUTPP (see Figure 8) −50 50 ps 50 ps 200 350 ps LVPECL INPUT-TO-LVPECL OUTPUT PARAMETER tpd(lh) Propagation delay rising edge VOX to VOX 320 600 ps tpd(hl) Propagation delay falling edge VOX to VOX 320 600 ps tsk(p) LVPECL pulse skew (see Note B in Figure 7) VOX to VOX 100 ps LVCMOS OUTPUT PARAMETER, Y1 tskLVCMOS(o) Output skew between the LVCMOS output Y1 and LVPECL output Y0 VOX to VDD / 2 (see Figure 7) tDuty Output duty cycle distortion (2) Measured at VDD / 2 tsk(pp) Part-to-part skew Y1 (see Note A in Figure 7) tpd(lh) Propagation delay rising edge from IN to Y1 VOX to VDD / 2 load (see Figure 9) 1.6 2.6 ns tpd(hl) Propagation delay falling edge from IN to Y1 VOX to VDD / 2 load (see Figure 9) 1.6 2.6 ns tr Output rise slew rate 20% to 80% of swing (see Figure 9) 1.4 2.3 V/ns tf Output fall slew rate 80% to 20% of swing (see Figure 9) 1.4 2.3 V/ns (1) (2) 1.6 ns −150 150 ps 300 ps For a 800-MHz signal, the 50-ps error would result into a duty cycle distortion of ±4% when driven by an ideal clock input signal. For a 200-MHz signal, the 150-ps error would result in a duty cycle distortion of ±3% when driven by an ideal clock input signal. 6.7 Jitter Characteristics over operating free-air temperature range (unless otherwise noted) PARAMETER tjitterLVPECL tjitterLVCMOS TEST CONDITIONS Additive phase jitter from input to LVPECL output Y0 (see Figure 1) Additive phase jitter from input to LVCMOS output Y1 (see Figure 2) MAX UNIT 12 kHz to 20 MHz, fout = 250 MHz to 800 MHz, divide by 1 mode MIN TYP 0.15 ps rms 50 kHz to 40 MHz, fout = 250 MHz to 800 MHz, divide by 1 mode 0.25 ps rms 12 kHz to 20 MHz, fout = 250 MHz, divide by 1 mode 0.25 ps rms 50 kHz to 40 MHz, fout = 250 MHz, divide by 1 mode 0.4 ps rms 6.8 Supply Current Electrical Characteristics over recommended operating free-air temperature range (unless otherwise noted) PARAMETER IDD IDDZ 6 TEST CONDITIONS MIN TYP MAX UNIT Full load All outputs enabled and terminated with 50 Ω to VDD − 2 V on LVPECL outputs and 10 pF on LVCMOS output, f = 800 MHz for LVPECL outputs and 200 MHz for LVCMOS, VDD = 3.3 V No load Outputs enabled, no output load, f = 800 MHz for LVPECL outputs and 200 MHz for LVCMOS, VDD = 3.6 V 85 mA All outputs 3-state by control logic, f = 0 Hz, VDD = 3.6 V 0.5 mA Supply current Supply current, 3-state Submit Documentation Feedback 100 mA Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 CDCM1802 www.ti.com SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 6.9 Control Input Characteristics over operating free-air temperature range (unless otherwise noted) TEST CONDITIONS PARAMETER MIN TYP MAX 42 60 78 Rpullup Internal pullup resistor on S0, S1, and EN input VIH(H) Three level input high, S0, S1, and EN pin (1) 0.9 × VDD VIM(M) Three level input MID, S0, S1, and EN pin 0.3 × VDD VIL(L) Three level low, S0, S1, and EN pin IIH Input current, S0, S1, and EN pin VI = VDD IIL Input current, S0, S1, and EN pin VI = GND (1) UNIT kΩ V 0.7 × VDD V 0.1 × VDD V –5 µA 85 µA 38 Leaving this pin floating automatically pulse the logic level high to VDD through an internal pullup resistor of 60 kΩ. 6.10 Timing Requirements MIN tsu Setup time, S0, S1, and EN pin before clock IN th Hold time, S0, S1, and EN pin after clock IN t(disable) Time between latching the EN low transition and when all outputs are disabled (how much time is required until the outputs turn off) t(enable) Time between latching the EN low-to-high transition and when outputs are enabled based on control settings (how much time passes before the outputs carry valid signals) NOM MAX UNIT 25 ns 0 ns 10 ns 1 μs 6.11 Bias Voltage VBB over operating free-air temperature range (unless otherwise noted) PARAMETER VBB Output reference voltage TEST CONDITIONS MIN VDD = 3 V–3.6 V, IBB = –0.2 mA VDD – 1.4 TYP MAX UNIT VDD – 1.2 Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 V 7 CDCM1802 SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 www.ti.com 6.12 Typical Characteristics −110 −100 VDD = 3.3 V TA = 25°C f = 622 MHz ÷1 Mode −120 VDD = 3.3 V TA = 25°C f = 250 MHz ÷1 Mode −105 −110 Additive Phase Noise − dBc/Hz Additive Phase Noise − dBc/Hz −115 −125 −130 −135 −140 −145 −150 −115 −120 −125 −130 −135 −140 −145 −150 −155 −155 −160 10 100 1k 10k 100k 1M 10M −160 10 100M f − Frequency Offset From Carrier − Hz 100 1k 10k 100k 1M 10M 100M f − Frequency Offset From Carrier − Hz G001 G002 Figure 1. Additive Phase Noise vs Frequency Offset From Carrier − LVPECL Figure 2. Additive Phase Noise vs Frequency Offset From Carrier − LVCMOS 0.90 3.5 0.85 VDD = 3.6 V VDD3 = 3.6 V 3.0 LVCMOS Output Swing − V LVPECL Output Swing − V 0.80 0.75 0.70 VDD = 3 V 0.65 0.60 0.55 VDD = 3.3 V 2.5 VDD3 = 3 V 2.0 VDD = 3.3 V 1.5 1.0 0.50 TA = 25°C Load = See Figure 10 0.5 0.45 0.40 0.1 TA = 25°C Load = 50 W to VDD − 2 V 0.3 0.5 0.7 0.0 0.9 1.1 1.3 1.5 25 75 125 175 225 275 325 375 425 475 f − Frequency − GHz f − Frequency − MHz G003 G004 Figure 3. Amplitude PECL Peak-to-Peak vs Frequency Figure 4. Amplitude CMOS Peak-to-Peak vs Frequency 4.0 110 VDD = 3.3 V 3.5 VBB − Output Reference Voltage − V ICC - Supply Current - mA 100 CMOS Running, PECL Off (Mode 10) CMOS and PECL Running, No Load CMOS Off, PECL Running CMOS and PECL Running (Mode 3) 90 80 70 60 50 0.1 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0.3 0.5 0.7 0.9 1.1 1.3 −5 1.5 5 10 15 20 25 30 35 G006 Figure 5. Supply current vs Frequency 8 0 I − Load − mA f - Frequency - GHz Figure 6. Output Reference Voltage (VBB) vs Load Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 CDCM1802 www.ti.com SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 7 Parameter Measurement Information IN IN Y0 Y0 tPHLO 0.5 x VDD1 Y1 tskLVCMOS(o) A. Part-to-part skew, tsk(pp), is calculated as the greater of: M− The difference between the fastest and the slowest tpd(LH)n across multiple devices M− The difference between the fastest and the slowest tpd(HL)n across multiple devices B. Pulse skew, tsk(p), is calculated as the magnitude of the absolute time difference between the high-to-low (tpd(HL) and the low-to-high (tpd(LH)) propagation delays when a single switching input causes Y0 to switch, tsk(p) = | tpd(HL) − tpd(LH) |. Pulse skew is sometimes referred to as pulse width distortion or duty cycle skew. Figure 7. Waveforms for Calculation of tsk(o) and tsk(pp) Y0 VOH Y0 VOL 80% 0V VOUT(pp) 20% |Y0 t Y0| tr tf Figure 8. LVPECL Differential Output Voltage and Rise and Fall Time VDD CDCM1802 1 lQ Y1 LVCMOS 1 lQ 10 pF Figure 9. LVCMOS Output Loading During Device Test Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 9 CDCM1802 SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 www.ti.com Parameter Measurement Information (continued) (VDD t 2 V) CDCM1802 50 Q Y0, Y0 LVPECL Figure 10. LVPECL Output Loading During Device Test 10 Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 CDCM1802 www.ti.com SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 8 Detailed Description 8.1 Overview The CDCM1802 is a clock buffer with a programmable divider. There is one LVCMOS and one LVPECL output. The LVCMOS output is specifically designed for driving 50-Ω transmission lines. It is delayed by 1.6 ns over the PECL output stage to minimize noise impact during signal transitions. Both outputs can be divided individually by 1, 2, 4, and 8. Divider settings can be selected with three 3-level control pins. 8.2 Functional Block Diagram LVCMOS Div 1 Div 2 Div 4 Div 8 IN IN Y1 Y0 LVPECL Y0 VBB Bias Generator VDD t 1.3 V (imax < 1.5 mA) Control S0 EN S1 8.3 Feature Description The CDCM1802 has two control pins, S0 and S1, to select different output mode settings. The S[1:0] pins are 3level inputs. Additionally, an enable pin EN is provided to disable or enable all outputs simultaneously. For singleended driver applications, the CDCM1802 provides a VBB output pin that can be directly connected to the unused input as a common-mode voltage reference. 8.4 Device Functional Modes 8.4.1 Control Pin Settings The CDCM1802 has three control pins, S0, S1, and the enable pin (EN) to select different output mode settings. All three inputs (S0, S1, EN) are 3-level inputs. In addition, the EN input allows disabling all outputs and place them into a Hi-Z (or tristate) output state when pulled to GND. Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 11 CDCM1802 SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 www.ti.com Device Functional Modes (continued) Setting for Mode 4: EN = VDD/2 S1 = 0 S0 = 1 CDCM1802 RS0 = open S0 RS1 = 0 S1 REN = 60lQ EN Figure 11. Control Pin Setting for Example Each control input incorporates a 60-kΩ pullup resistor. Thus, it is easy to choose the input setting by designing a resistor pad between the control input and GND. To choose a logic zero, the resistor value must be zero. Setting the input high requires leaving the resistor pad empty (no resistor installed). For setting the input to VDD/2, the installed resistor needs a value of 60 kΩ with a tolerance better or equal to 10%. Table 1. Selection Mode Table (1) MODE EN S1 S0 0 0 X 1 VDD/2 2 VDD/2 3 1 4 5 LVPECL (1) LVCMOS Y0 Y1 X Off (high-z) Off (high-z) 0 VDD/2 /1 /1 VDD/2 1 /1 /2 0 0 /1 /4 VDD/2 0 1 /2 /2 1 0 1 /2 /4 6 VDD/2 0 0 /4 /4 7 VDD/2 1 0 /4 /8 8 VDD/2 VDD/2 VDD/2 /8 /1 9 1 1 0 /8 /4 10 1 1 1 Off (high-z) /4 The LVPECL outputs are open emitter stages. Thus, if you leave the unused LVPECL output Y0 unconnected, then the current consumption is minimized and noise impact to remaining outputs is neglectable. Also, each output can be individually disabled by connecting the corresponding VDD input to GND. 8.4.2 Device Behavior During RESET and Control Pin Switching 8.4.2.1 Output Behavior When Enabling the Device (EN = 0 → 1) In disable mode (EN = 0), all output drivers are switched in high-Z mode. The bandgap, current references, the amplifier, and the S0 and S1 control inputs are also switched off. In the same mode, all flip-flops will be reset. The typical current consumption is likely below 500 µA (to be measured). When the device will be enabled again it takes maximal 1 µs for the settling of the reference voltage and currents. During this time the output Y0 and Y0 drive a high signal. Y1 is unknown (could be high or low). After the settle time, the outputs go into the low state. Due to the synchronization of each output driver signal with the input clock, the state of the waveforms after enabling the device look like those shown in Figure 12. The inverting input and output signal is not included. The Y:/1 waveform is the undivided output driver state. 12 Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 CDCM1802 www.ti.com SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 1 us EN IN Y:/1 High-Z Undefined Y:/2 High-Z Undefined Y:/4 High-Z Undefined Low Low Low Signal State After the Device is Enabled (IN = Low) 1 us EN Undivided State is Valid After the First Positive Transition of the Input Clock IN Y:/1 High-Z Undefined Y:/2 High-Z Undefined Y:/4 High-Z Undefined Low Low Low Signal State After the Device is Enabled (IN = High) Figure 12. Waveforms 8.4.2.2 Enabling a Single Output Stage If a single output stage becomes enabled: • Y0 will either be low or high (undefined). • Y0 will be the inverted signal of Y0. With the first positive clock transition, the undivided output becomes the input clock state. If a divide mode is used, the divided output states are equal to the actual internal divider. The internal divider does not get a reset while enabling single output drivers. Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 13 CDCM1802 SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 ENABLE Yx: www.ti.com Disabled Enabled Undivided State is Valid After the First Positive Transition of the Input Clock IN Y:/1 High-Z Undefined Y:/x High-Z Undefined Divider State Figure 13. Signal State After an Output Driver Becomes Enabled While IN = 0 ENABLE Yx: Disabled Enabled Undivided State is Valid After the First Positive Transition of the Input Clock IN Y:/1 High-Z Undefined Y:/x High-Z Undefined Divider State Figure 14. Signal State After an Output Driver Becomes Enabled While IN = 1 14 Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 CDCM1802 www.ti.com SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 9 Application and Implementation NOTE Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality. 9.1 Application Information 9.1.1 LVPECL Receiver Input Termination The input of the CDCM1802 has high impedance and comes with a very large common mode voltage range. For optimized noise performance it is recommended to properly terminate the PCB trace (transmission line). Additional termination techniques can be found in the following application notes: SCAA062 and SCAA059. CDCM1802 IN 50 Q CAC 150 Q 50 Q LVPECL 50 Q IN 50 Q 150 Q CAC VBB C Figure 15. Recommended AC-Coupling LVPECL Receiver Input Termination Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 15 CDCM1802 SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 www.ti.com Application Information (continued) CDCM1802 130 Q IN 50 Q 83 Q LVPECL 130 Q IN 50 Q 83 Q Figure 16. Recommended DC-Coupling LVPECL Receiver Input Termination 9.1.2 LVCMOS Receiver Input Termination CDCM1802 LVCMOS IN 50 Q CAC Rdc IN VBB CCT NOTE: CAC − AC-coupling capacitor (for example, 10 nF) CCT − Capacitor keeps voltage at IN constant (for example, 10 nF) Rdc − Load and correct duty cycle (for example, 50 Ω) VBB − Bias voltage output Figure 17. Typical Application Setting for Single-Ended Input Signals Driving the CDCM1802 16 Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 CDCM1802 www.ti.com SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 9.2 Typical Application Figure 18 shows a fanout buffer application. 3.3 V PHY IN 100 MHz LVPECL Hi-Z Y1 from backplane IN 50 VBB Setting for Mode 3: EN = 1 RS0 = 0 S1 = 0 S0 = 0 RS1 = 0 ASIC CDCLVP1802 3.3 V S0 130 S1 Y0 REN = open EN 83 Figure 18. Typical Application Schematic, CDCM1802 9.2.1 Design Requirements The CDCM1802 shown in Figure 18 is configured to be able to select an 100-MHz LVPECL clock from the backplane. The signal can be fanned out to desired devices, as shown. The CDCM1802 offers internal dividers for both the LVCMOS and LVPECL output. In the example the LVCMOS output is divided by 4 and the LVPECL output is divided by 1. • • • The PHY device receive a single ended 25-MHz signal. Optionally a series resistance can be placed close to the output to match transmission line impedance and reduce reflections. The ASIC is capable of DC coupling with a 3.3-V LVPECL driver such as the CDCM1802. This ASIC features internal termination so no additional components are needed. S0, S1, EN needs to be set accordingly to ensure the required divider setting. 9.2.2 Detailed Design Procedure Refer to LVPECL Receiver Input Termination for proper input terminations, dependent on single-ended or differential inputs. Refer to Figure 9 and Figure 10 for output termination schemes depending on the receiver application. Refer to Table 1 for setting the desired divider modes. Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 17 CDCM1802 SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 www.ti.com Typical Application (continued) 9.2.3 Application Curve Input (Vectron C5310A1) = 83 fs, rms Output (LVPECL, divide 1) = 134 fs, rms additive jitter = 105 fs, rms (typ) Figure 19. Additive Jitter Performance 18 Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 CDCM1802 www.ti.com SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 10 Power Supply Recommendations High-performance clock buffers are sensitive to noise on the power supply, which can dramatically increase the additive jitter of the buffer. Thus, it is essential to reduce noise from the system power supply, especially when jitter or phase noise is very critical to applications. Filter capacitors are used to eliminate the low-frequency noise from the power supply, where the bypass capacitors provide the very low impedance path for high-frequency noise and guard the power-supply system against the induced fluctuations. These bypass capacitors also provide instantaneous current surges as required by the device and must have low equivalent series resistance (ESR). To properly use the bypass capacitors, they must be placed very close to the power-supply terminals and laid out with short loops to minimize inductance. It is recommended to add as many high-frequency (for example, 0.1-μF) bypass capacitors as there are supply terminals in the package. It is recommended, but not required, to insert a ferrite bead between the board power supply and the chip power supply that isolates the high-frequency switching noises generated by the clock driver; these beads prevent the switching noise from leaking into the board supply. It is imperative to choose an appropriate ferrite bead with very low DC resistance to provide adequate isolation between the board supply and the chip supply, as well as to maintain a voltage at the supply terminals that is greater than the minimum voltage required for proper operation. Figure 20 illustrates this recommended power-supply decoupling method. Board Supply VCC Chip Supply Ferrite Bead C 10 mF C 1 mF C 0.1 mF (x3) Figure 20. Power-Supply Decoupling 11 Layout 11.1 Layout Guidelines TI recommends taking special care of the PCB design for good thermal flow from the VQFN 16-pin package to the PCB. The current consumption of the CDCM1802 is fixed. JEDEC JESD51−7 specifies thermal conductivity for standard PCB boards. Modeling the CDCM1802 with a 4−layer JEDEC board (including four thermal vias) results into 37.5°C max temperature with a RθJA of 40.84°C for 25°C ambient temperature. To ensure sufficient thermal flow, it is recommended to design with four thermal vias in applications. See the SCBA017 and the SLUA271 application notes for further package-related information. Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 19 CDCM1802 SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 www.ti.com 11.2 Layout Example Package Thermal Pad (Underside) Thermal Via Dia 0.020 In. Top Side Island Heat Dissipation VSS Copper Plane VSS Copper Plane Figure 21. Recommended Thermal Via Placement 20 Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 CDCM1802 www.ti.com SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 11.3 Thermal Considerations Table 2. Package Thermal Resistance PARAMETER RθJA (1) VQFN−16 package thermal resistance with thermal vias in PCB (1) TEST CONDITIONS MIN 4-layer JEDEC test board (JESD51−7) with four thermal vias of 22-mil diameter each, airflow = 0 ft/min TYP MAX UNIT 48.4 °C/W It is recommended to provide four thermal vias to connect the thermal pad of the package effectively with the PCB and ensure a good heat sink. Example: Calculation of the junction-lead temperature with a 4-layer JEDEC test board using four thermal vias: TChassis = 85°C (temperature of the chassis) Peffective = Imax × Vmax = 85 mA × 3.6 V = 306 mW (max power consumption inside the package) ΔTJunction = RθJA × Peffective = 40.8°C/W × 306 mW = 12.48°C TJunction = ΔTJunction + TChassis = 12.48°C + 85°C = 97.48°C (the maximum junction temperature of Tdie−max = 125°C is not violated) Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 21 CDCM1802 SCAS759B – APRIL 2004 – REVISED NOVEMBER 2015 www.ti.com 12 Device and Documentation Support 12.1 Device Support 12.1.1 Third-Party Products Disclaimer TI'S PUBLICATION OF INFORMATION REGARDING THIRD-PARTY PRODUCTS OR SERVICES DOES NOT CONSTITUTE AN ENDORSEMENT REGARDING THE SUITABILITY OF SUCH PRODUCTS OR SERVICES OR A WARRANTY, REPRESENTATION OR ENDORSEMENT OF SUCH PRODUCTS OR SERVICES, EITHER ALONE OR IN COMBINATION WITH ANY TI PRODUCT OR SERVICE. 12.2 Documentation Support 12.2.1 Related Documentation SCAA062: DC-Coupling Between Differential LVPECL, LVDS, HSTL, and CML SCAA059: AC-Coupling Between Differential LVPECL, LVDC, HSTL, and CML SCBA017: Quad Flatpack No-Lead Logic Packages SLUA271: QFN/SON PCB Attachment 12.3 Community Resources The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of Use. TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help solve problems with fellow engineers. Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and contact information for technical support. 12.4 Trademarks E2E is a trademark of Texas Instruments. All other trademarks are the property of their respective owners. 12.5 Electrostatic Discharge Caution These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. 12.6 Glossary SLYZ022 — TI Glossary. This glossary lists and explains terms, acronyms, and definitions. 13 Mechanical, Packaging, and Orderable Information The following pages include mechanical, packaging, and orderable information. This information is the most current data available for the designated devices. This data is subject to change without notice and revision of this document. For browser-based versions of this data sheet, refer to the left-hand navigation. 22 Submit Documentation Feedback Copyright © 2004–2015, Texas Instruments Incorporated Product Folder Links: CDCM1802 PACKAGE OPTION ADDENDUM www.ti.com 15-Apr-2015 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (°C) Device Marking (4/5) CDCM1802RGTR ACTIVE QFN RGT 16 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 85 AJW CDCM1802RGTRG4 ACTIVE QFN RGT 16 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 85 AJW CDCM1802RGTT ACTIVE QFN RGT 16 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 85 AJW CDCM1802RGTTG4 ACTIVE QFN RGT 16 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 85 AJW (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com 15-Apr-2015 Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. 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Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 17-Apr-2015 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant CDCM1802RGTR QFN RGT 16 3000 330.0 12.4 3.3 3.3 1.6 8.0 12.0 Q2 CDCM1802RGTT QFN RGT 16 250 330.0 12.4 3.3 3.3 1.6 8.0 12.0 Q2 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 17-Apr-2015 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) CDCM1802RGTR QFN RGT 16 3000 340.5 338.1 20.6 CDCM1802RGTT QFN RGT 16 250 340.5 338.1 20.6 Pack Materials-Page 2 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. 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