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Integrated Circuit Systems, Inc.
ICS8535-21
LOW SKEW, 1-TO-2 LVCMOS/LVTTL-TO-3.3V LVPECL FANOUT BUFFER
FEATURES
* 2 differential 3.3V LVPECL outputs * Selectable CLK0 or CLK1 inputs for redundant and multiple frequency fanout applications * CLK0 or CLK1 can accept the following input levels: LVCMOS or LVTTL * Maximum output frequency: 266MHz * Translates LVCMOS and LVTTL levels to 3.3V LVPECL levels * Output skew: 20ps (maximum) * Part-to-part skew: 300ps (maximum) * Propagation delay: 1.6ns (maximum) * Additive phase jitter, RMS: 0.03ps (typical) * 3.3V operating supply * 0C to 70C ambient operating temperature * Industrial temperature information available upon request
GENERAL DESCRIPTION
The ICS8535-21 is a low skew, high performance 1-to-2 LVCMOS/LVTTL-to-3.3V LVPECL fanout HiPerClockSTM buffer and a member of the HiPerClockSTM family of High Performance Clock Solutions from ICS. The ICS8535-21 has two single-ended clock inputs. The single-ended clock input accepts LVCMOS or LVTTL input levels and translate them to 3.3V LVPECL levels. The clock enable is internally synchronized to eliminate runt clock pulses on the output during asynchronous assertion/deassertion of the clock enable pin.
ICS
Guaranteed output and part-to-part skew characteristics make the ICS8535-21 ideal for those applications demanding well defined performance and repeatability.
BLOCK DIAGRAM
CLK_EN D Q LE CLK0 CLK1 0 1 Q0 nQ0 Q1 nQ1 CLK_SEL
PIN ASSIGNMENT
VEE CLK_EN CLK_SEL CLK0 VEE CLK1 VCC 1 2 3 4 5 6 7 14 13 12 11 10 9 8 VCC Q0 nQ0 nc Q1 nQ1 VCC
ICS8535-21
14-Lead TSSOP 4.4mm x 5.0mm x 0.92mm body package G Package Top View
8535AG-21
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REV. A OCTOBER 20, 2004
Integrated Circuit Systems, Inc.
ICS8535-21
LOW SKEW, 1-TO-2 LVCMOS/LVTTL-TO-3.3V LVPECL FANOUT BUFFER
Type Description
TABLE 1. PIN DESCRIPTIONS
Number 1, 5 2 3 4 6 7, 8, 14 Name VEE CLK_EN CLK_SEL CLK0 CLK1 VCC Power Input Input Input Input Power Negative supply pins. Synchronizing clock enable. When HIGH, clock outputs follow clock input. Pullup When LOW, Q outputs are forced low, nQ outputs are forced high. LVCMOS / LVTTL interface levels. Clock select input. When HIGH, selects CLK1 input. Pulldown When LOW, selects CLK0 input. LVCMOS / LVTTL interface levels. Pulldown LVCMOS / LVTTL clock input. Pulldown LVCMOS / LVTTL clock input. Positive supply pins.
9, 10 nQ1, Q1 Output Differential output pair. LVPECL interface levels. 11 nc Unused No connect. 12 , 13 nQ0, Q0 Output Differential output pair. LVPECL interface levels. NOTE: Pullup and Pulldown refer to internal input resistors. See Table 2, Pin Characteristics, for typical values.
TABLE 2. PIN CHARACTERISTICS
Symbol CIN RPULLUP RPULLDOWN Parameter Input Capacitance Input Pullup Resistor Input Pulldown Resistor Test Conditions Minimum Typical 4 51 51 Maximum Units pF K K
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REV. A OCTOBER 20, 2004
Integrated Circuit Systems, Inc.
ICS8535-21
LOW SKEW, 1-TO-2 LVCMOS/LVTTL-TO-3.3V LVPECL FANOUT BUFFER
Inputs Outputs Selected Source CLK0 CLK1 CLK0 Q0, Q1 Disabled; LOW Disabled; LOW Enabled nQ0, nQ1 Disabled; HIGH Disabled; HIGH Enabled
TABLE 3A. CONTROL INPUT FUNCTION TABLE
CLK_EN 0 0 1 CLK_SEL 0 1 0
1 1 CLK1 Enabled Enabled After CLK_EN switches, the clock outputs are disabled or enabled following a rising and falling input clock edge as show in Figure 1. In the active mode, the state of the outputs are a function of the CLK0 and CLK1 inputs as described in Table 3B.
Disabled
Enabled
CLK0, CLK1
CLK_EN
nQ0, nQ1 Q0, Q1
FIGURE 1. CLK_EN TIMING DIAGRAM
TABLE 3B. CLOCK INPUT FUNCTION TABLE
Inputs CLK0 or CLK1 0 1 Q0, Q1 LOW HIGH Outputs nQ0, nQ1 HIGH LOW
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REV. A OCTOBER 20, 2004
Integrated Circuit Systems, Inc.
ICS8535-21
LOW SKEW, 1-TO-2 LVCMOS/LVTTL-TO-3.3V LVPECL FANOUT BUFFER
4.6V -0.5V to VCC + 0.5V 50mA 100mA 93.2C/W (0 lfpm) -65C to 150C NOTE: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These ratings are stress specifications only. Functional operation of product at these conditions or any conditions beyond those listed in the DC Characteristics or AC Characteristics is not implied. Exposure to absolute maximum rating conditions for extended periods may affect product reliability.
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VCC Inputs, VI Outputs, IO Continuous Current Surge Current Package Thermal Impedance, JA Storage Temperature, TSTG
TABLE 4A. POWER SUPPLY DC CHARACTERISTICS, VCC = 3.3V5%, TA = 0C TO 70C
Symbol VCC IEE Parameter Positive Supply Voltage Power Supply Current Test Conditions Minimum 3.135 Typical 3.3 Maximum 3.465 50 Units V mA
TABLE 4B. LVCMOS / LVTTL DC CHARACTERISTICS, VCC = 3.3V5%, TA = 0C TO 70C
Symbol VIH VIL IIH IIL Parameter Input High Voltage Input Low Voltage Input High Current Input Low Current CLK0, CLK1 CLK_EN, CLK_SEL CLK0, CLK1 CLK_EN, CLK_SEL CLK0, CLK1, CLK_SEL CLK_EN CLK0, CLK1, CLK_SEL CLK_EN VIN = VCC = 3.465V VIN = VCC = 3.465V VIN = 0V, VCC = 3.465V VIN = 0V, VCC = 3.465V -5 -150 Test Conditions Minimum 2 2 -0.3 -0.3 Typical Maximum VCC + 0.3 VCC + 0.3 1.3 0.8 150 5 Units V V V V A A A A
TABLE 4C. LVPECL DC CHARACTERISTICS, VCC = 3.3V5%, TA = 0C TO 70C
Symbol VOH VOL VSWING Parameter Output High Voltage; NOTE 1 Output Low Voltage; NOTE 1 Peak-to-Peak Output Voltage Swing Test Conditions Minimum VCC - 1.4 VCC - 2.0 0.6 Typical Maximum VCC - 0.9 VCC - 1.7 1.0 Units V V V
NOTE 1: Outputs terminated with 50 to VCC - 2V.
8535AG-21
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REV. A OCTOBER 20, 2004
Integrated Circuit Systems, Inc.
ICS8535-21
LOW SKEW, 1-TO-2 LVCMOS/LVTTL-TO-3.3V LVPECL FANOUT BUFFER
Test Conditions 266MHz Minimum 1.0 Typical Maximum 266 1.6 20 300 156.25MHz @ Integration Range: 12KHz - 20MHz 20% to 80% @ 50MHz 300 0.03 600 55 Units MHz ns ps ps ps ps %
TABLE 5. AC CHARACTERISTICS, VCC = 3.3V5%, TA = 0C TO 70C
Symbol fMAX tPD Parameter Output Frequency Propagation Delay; NOTE 1 Output Skew; NOTE 2, 5 Par t-to-Par t Skew; NOTE 3, 5 Buffer Additive Phase Jitter, RMS; refer to Additive Phase Jitter Section, NOTE 4 Output Rise/Fall Time
t sk(o) t sk(pp) t jit
tR/tF
odc Output Duty Cycle 200MHz 45 All parameters measured at 266MHz unless noted otherwise. The cycle-to-cycle jitter on the input will equal the jitter on the output. The par t does not add jitter. NOTE 1: Measured from the VCC/2 of the input to the differential output crossing point. NOTE 2: Defined as skew between outputs at the same supply voltage and with equal load conditions. Measured at the output differential cross points. NOTE 3: Defined as skew between outputs on different devices operating at the same supply voltages and with equal load conditions. Using the same type of inputs on each device, the outputs are measured at the differential cross points. NOTE 4: Driving only one input clock. NOTE 5: This parameter is defined in accordance with JEDEC Standard 65.
8535AG-21
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REV. A OCTOBER 20, 2004
Integrated Circuit Systems, Inc.
ICS8535-21
LOW SKEW, 1-TO-2 LVCMOS/LVTTL-TO-3.3V LVPECL FANOUT BUFFER
ADDITIVE PHASE JITTER
The spectral purity in a band at a specific offset from the fundamental compared to the power of the fundamental is called the dBc Phase Noise. This value is normally expressed using a Phase noise plot and is most often the specified plot in many applications. Phase noise is defined as the ratio of the noise power present in a 1Hz band at a specified offset from the fundamental frequency to the power value of the fundamental. This ratio is expressed in decibels (dBm) or a ratio of the power
0 -10 -20 -30 -40 -50
in the 1Hz band to the power in the fundamental. When the required offset is specified, the phase noise is called a dBc value, which simply means dBm at a specified offset from the fundamental. By investigating jitter in the frequency domain, we get a better understanding of its effects on the desired application over the entire time record of the signal. It is mathematically possible to calculate an expected bit error rate given a phase noise plot.
Input/Output Additive Phase Jitter,
Integration Range: 12KHz - 20MHz at 156.25MHz = 0.03ps (typical)
SSB PHASE NOISE dBc/HZ
-60 -70 -80 -90 -100 -110 -120 -130 -140 -150 -160 -170 -180 -190
1k
10k
100k
1M
10M
100M
OFFSET FROM CARRIER FREQUENCY (HZ)
As with most timing specifications, phase noise measurements have issues. The primary issue relates to the limitations of the equipment. Often the noise floor of the equipment is higher than the noise floor of the device. This is illustrated above. The device meets the noise floor of what is shown, but can actually be lower. The phase noise is dependant on the input source and measurement equipment.
8535AG-21
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REV. A OCTOBER 20, 2004
Integrated Circuit Systems, Inc.
ICS8535-21
LOW SKEW, 1-TO-2 LVCMOS/LVTTL-TO-3.3V LVPECL FANOUT BUFFER
PARAMETER MEASUREMENT INFORMATION
2V
VCC
Qx
SCOPE
PART 1 nQx Qx
LVPECL
nQx
PART 2 nQy Qy
VEE
tsk(pp)
-1.3V 0.165V
3.3V OUTPUT LOAD AC TEST CIRCUIT
PART-TO-PART SKEW
nQx 80% Qx nQy Qy Clock Outputs 20% tR tF 80% VSW I N G 20%
tsk(o)
OUTPUT SKEW
OUTPUT RISE/FALL TIME
nQ0, nQ1 CLK0, CLK1 nQ0, nQ1 Q0, Q1
tPD
Q0, Q1
Pulse Width t
PERIOD
odc =
t PW t PERIOD
PROPAGATION DELAY
8535AG-21
OUTPUT DUTY CYCLE/PULSE WIDTH/PERIOD
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REV. A OCTOBER 20, 2004
Integrated Circuit Systems, Inc.
ICS8535-21
LOW SKEW, 1-TO-2 LVCMOS/LVTTL-TO-3.3V LVPECL FANOUT BUFFER APPLICATION INFORMATION
TERMINATION FOR LVPECL OUTPUTS
The clock layout topology shown below is a typical termination for LVPECL outputs. The two different layouts mentioned are recommended only as guidelines. FOUT and nFOUT are low impedance follower outputs that generate ECL/LVPECL compatible outputs. Therefore, terminating resistors (DC current path to ground) or current sources must be used for functionality. These outputs are designed to drive 50 transmission lines. Matched impedance techniques should be used to maximize operating frequency and minimize signal distortion. Figures 2A and 2B show two different layouts which are recommended only as guidelines. Other suitable clock layouts may exist and it would be recommended that the board designers simulate to guarantee compatibility across all printed circuit and clock component process variations.
3.3V
Zo = 50
125
FOUT FIN
125
Zo = 50 FOUT FIN
Zo = 50 50 1 RTT = Z ((VOH + VOL) / (VCC - 2)) - 2 o 50 VCC - 2V RTT
Zo = 50 84 84
FIGURE 2A. LVPECL OUTPUT TERMINATION
FIGURE 2B. LVPECL OUTPUT TERMINATION
8535AG-21
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REV. A OCTOBER 20, 2004
Integrated Circuit Systems, Inc.
ICS8535-21
LOW SKEW, 1-TO-2 LVCMOS/LVTTL-TO-3.3V LVPECL FANOUT BUFFER
power pin. For ICS8535-21, the unused clock outputs can be left floating.
SCHEMATIC EXAMPLE
Figure 3 shows a schematic example of the ICS8535-21. The decoupling capacitors should be physically located near the
Zo = 50
+
Zo = 50
-
VCC = 3.3V
R2 50
R1 50
U2 CLK_EN CLK_SEL CLK0 CLK1 1 2 3 4 5 6 7 VEE CLK_EN CLK_SEL CLK0 VEE CLK1 VCC VCC Q0 nQ0 nc Q1 nQ1 VCC 14 13 12 11 10 9 8
R3 50
8535-21 Vcco = 3.3V
R4 133 VCC
R6 133 +
(U1-7)
(U1-8)
(U1-14)
Zo = 50 C4 .1uF
C1 10uf
C2 .1uF
C3 .1uF
Zo = 50 R5 82.5 R7 82.5
-
Optional Termination
FIGURE 3. ICS8535-21 LVPECL BUFFER SCHEMATIC EXAMPLE
8535AG-21
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REV. A OCTOBER 20, 2004
Integrated Circuit Systems, Inc.
ICS8535-21
LOW SKEW, 1-TO-2 LVCMOS/LVTTL-TO-3.3V LVPECL FANOUT BUFFER POWER CONSIDERATIONS
This section provides information on power dissipation and junction temperature for the ICS8535-21. Equations and example calculations are also provided.
1. Power Dissipation. The total power dissipation for the ICS8535-21 is the sum of the core power plus the power dissipated in the load(s). The following is the power dissipation for VCC = 3.3V + 5% = 3.465V, which gives worst case results. NOTE: Please refer to Section 3 for details on calculating power dissipated in the load.
* *
Power (core)MAX = VCC_MAX * IEE_MAX = 3.465V * 50mA = 173.25mW Power (outputs)MAX = 30mW/Loaded Output pair If all outputs are loaded, the total power is 2 x 30mW = 60mW
Total Power_MAX (3.465V, with all outputs switching) = 173.25mW + 60mW = 233.25mW
2. Junction Temperature. Junction temperature, Tj, is the temperature at the junction of the bond wire and bond pad and directly affects the reliability of the device. The maximum recommended junction temperature for HiPerClockSTM devices is 125C.
The equation for Tj is as follows: Tj = JA * Pd_total + TA Tj = Junction Temperature JA = Junction-to-Ambient Thermal Resistance Pd_total = Total Device Power Dissipation (example calculation is in section 1 above) TA = Ambient Temperature In order to calculate junction temperature, the appropriate junction-to-ambient thermal resistance JA must be used. Assuming a moderate air low of 200 linear feet per minute and a multi-layer board, the appropriate value is 85.5C/W per Table 6 below. Therefore, Tj for an ambient temperature of 70C with all outputs switching is: 70C + 0.233W * 85.5C/W = 90C. This is well below the limit of 125C. This calculation is only an example, and the Tj will obviously vary depending on the number of outputs that are loaded, supply voltage, air flow, and the type of board (single layer or multi-layer).
TABLE 6. THERMAL RESISTANCE JA FOR 14-PIN TSSOP, FORCED CONVECTION
JA by Velocity (Linear Feet per Minute)
0
Single-Layer PCB, JEDEC Standard Test Boards Multi-Layer PCB, JEDEC Standard Test Boards 146.4C/W 93.2C/W
200
125.2C/W 85.5C/W
500
112.1C/W 81.2C/W
NOTE: Most modern PCB designs use multi-layered boards. The data in the second row pertains to most designs.
8535AG-21
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REV. A OCTOBER 20, 2004
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3. Calculations and Equations.
ICS8535-21
LOW SKEW, 1-TO-2 LVCMOS/LVTTL-TO-3.3V LVPECL FANOUT BUFFER
The purpose of this section is to derive the power dissipated into the load. LVPECL output driver circuit and termination are shown in Figure 4.
VCC
Q1
VOUT RL 50 VCC - 2V
FIGURE 4. LVPECL DRIVER CIRCUIT AND TERMINATION
To calculate worst case power dissipation into the load, use the following equations which assume a 50 load, and a termination voltage of V - 2V.
CC
*
For logic high, VOUT = V (V
CC_MAX
OH_MAX
=V
CC_MAX
- 0.9V
-V
OH_MAX
) = 0.9V =V - 1.7V
*
For logic low, VOUT = V (V
CC_MAX
OL_MAX
CC_MAX
-V
OL_MAX
) = 1.7V
Pd_H is power dissipation when the output drives high. Pd_L is the power dissipation when the output drives low. Pd_H = [(V - (V - 2V))/R ] * (V
L
OH_MAX
CC_MAX
CC_MAX
-V
OH_MAX
) = [(2V - (V
CC_MAX
-V
OH_MAX
))/R ] * (V
L
CC_MAX
-V
OH_MAX
)=
[(2V - 0.9V)/50] * 0.9V = 19.8mW ))/R ] * (V
L
Pd_L = [(V
OL_MAX
- (V
CC_MAX
- 2V))/R ] * (V
L
CC_MAX
-V
OL_MAX
) = [(2V - (V
CC_MAX
-V
OL_MAX
CC_MAX
-V
OL_MAX
)=
[(2V - 1.7V)/50] * 1.7V = 10.2mW
Total Power Dissipation per output pair = Pd_H + Pd_L = 30mW
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REV. A OCTOBER 20, 2004
Integrated Circuit Systems, Inc.
ICS8535-21
LOW SKEW, 1-TO-2 LVCMOS/LVTTL-TO-3.3V LVPECL FANOUT BUFFER RELIABILITY INFORMATION
TABLE 7. JAVS. AIR FLOW TABLE FOR 14 LEAD TSSOP
JA by Velocity (Linear Feet per Minute)
0
Single-Layer PCB, JEDEC Standard Test Boards Multi-Layer PCB, JEDEC Standard Test Boards 146.4C/W 93.2C/W
200
125.2C/W 85.5C/W
500
112.1C/W 81.2C/W
NOTE: Most modern PCB designs use multi-layered boards. The data in the second row pertains to most designs.
TRANSISTOR COUNT
The transistor count for ICS8535-21 is: 412
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REV. A OCTOBER 20, 2004
Integrated Circuit Systems, Inc.
ICS8535-21
LOW SKEW, 1-TO-2 LVCMOS/LVTTL-TO-3.3V LVPECL FANOUT BUFFER
PACKAGE OUTLINE - G SUFFIX FOR 14 LEAD TSSOP
TABLE 8. PACKAGE DIMENSIONS
SYMBOL N A A1 A2 b c D E E1 e L aaa 0.45 0 -4.30 0.65 BASIC 0.75 8 0.10 -0.05 0.80 0.19 0.09 4.90 6.40 BASIC 4.50 Millimeters Minimum 14 1.20 0.15 1.05 0.30 0.20 5.10 Maximum
REFERENCE DOCUMENT: JEDEC PUBLICATION 95, MO-153
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REV. A OCTOBER 20, 2004
<
Integrated Circuit Systems, Inc.
ICS8535-21
LOW SKEW, 1-TO-2 LVCMOS/LVTTL-TO-3.3V LVPECL FANOUT BUFFER
Marking Package 14 lead TSSOP 14 lead TSSOP on Tape and Reel Count 94 per tube 2500 Temperature 0C to 70C 0C to 70C
TABLE 9. ORDERING INFORMATION
Part/Order Number ICS8535AG-21 ICS8535AG-21T 8535AG21 8535AG21
The aforementioned trademark, HiPerClockSTM is a trademark of Integrated Circuit Systems, Inc. or its subsidiaries in the United States and/or other countries. While the information presented herein has been checked for both accuracy and reliability, Integrated Circuit Systems, Incorporated (ICS) assumes no responsibility for either its use or for infringement of any patents or other rights of third parties, which would result from its use. No other circuits, patents, or licenses are implied. This product is intended for use in normal commercial applications. Any other applications such as those requiring extended temperature range, high reliability, or other extraordinary environmental requirements are not recommended without additional processing by ICS. ICS reserves the right to change any circuitry or specifications without notice. ICS does not authorize or warrant any ICS product for use in life support devices or critical medical instruments. 8535AG-21
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