ICS7152
Spread Spectrum Clock Generator
Description
The ICS7152-01, -02, -11, and -12 are clock
generators for EMI (Electro Magnetic Interference) reduction (e below for frequency ranges and
multiplier ratios). Spectral peaks can be attenuated by slightly modulating the oscillation frequency. Both down and center spread profiles are lectable. Center spread maintains an average frequency equal to an unspread clock. Down spread meets maximum frequency specs over the entire modualtion cycle.
Features
•Operating voltage of 3.3 V ±0.3 V •Packaged in 8-pin SOIC
•Input frequency range of 16.6 to 134.0 MHz •Output frequency range of 16.6 to 134.0 MHz •
Provides a spread spectrum clock output (±0.5%, ±1.5% center spread; -1.0%, -3.0% down spread)
•Advanced, low-power CMOS process •Industrial temperature range available •Available in Pb (lead) free package
Block Diagram
Product Lineup
Product
Input Frequency Range
Modulation Type
Modulation Enable Pin
ICS7152M-01, ICS7152MI-0116.6 MHz to 67 MHz Down spread
Y es
ICS7152M-02, ICS7152MI-0240.0 MHz to 134.0 MHz ICS7152M-11, ICS7152MI-1116.6 MHz to 67.0 MHz Center spread
ICS7152M-12, ICS7152MI-12
40.0 MHz to 134.0 MHz
Spread Spectrum Clock Generator
Modulation Enable Setting Table
SEL Modulation Rate Setting Table
Frequency Setting Table
Pin Descriptions
XENS Pin 8Spread Spectrum
0ON 1
OFF
SEL Pin 4(note1)
Spread Direction
Spread Percentage (%)
Part Number
0Center ±0.5ICS7152M-11, ICS7152M-12Down
-1.0ICS7152M-01, ICS7152M-021Center ±1.5ICS7152M-11, ICS7152M-12Down
-3.0
ICS7152M-01, ICS7152M-02
FREQ Pin 7
Frequency
016.6 to 40 MHz ICS7152M-01, ICS7152M-1140 to 80 MHz
ICS7152M-02, ICS7152M-12133 to 67 MHz ICS7152M-01, ICS7152M-1166 to 134 MHz
ICS7152M-02, ICS7152M-12
Pin Number
Pin Name
Pin Type
Pin Description
1XIN Input Crystal resonator connection pin/clock input pin.2XOUT Output Crystal resonator connection pin.3GND Power Connect to ground.4SEL Input Modulation rate tting pin.5CKOUT Output Modulated clock output pin.6VDD Power Connect to +3.3 V.7FREQ Input Frequency tting pin.8
XENS
Output
Modulation enable tting pin.
Spread Spectrum Clock Generator
External Components
The ICS7152 requires a minimum number of external components for proper operation.
Decoupling Capacitor
A decoupling capacitor of 0.01µF must be connected between GND and VDD on pin 6, as clo to this pin as possible. For optimum device performance, the decoupling capacitor should be mounted on the component side of the PCB. Avoid the u of vias in the decoupling circuit.
Series Termination Resistor
Series termination should be ud on the clock output. To ries terminate a 50Ω trace (a commonly ud trace impedance) place a 27Ω resistor in ries with the clock line, as clo to the clock output pin as possible. The nominal impedance of the clock output is 25Ω.
PCB Layout Recommendations
For optimum device performance and lowest output pha noi, the following guidelines should be obrved.
1) An optimum layout is one with all components on the same side of the board, minimizing vias through other signal layers. Other signal traces should be routed away from the ICS7152. This includes signal traces just underneath the device, or on layers adjacent to the ground plane layer ud by the device.Crystal Information
The crystal ud should be a fundamental mode, parallel resonant. Crystal capacitors should be connected from pins X1 to ground and X2 to ground to optimize the initial accuracy. The value of the capacitors is given by the following equation:
Crystal caps (pF) = (C L - 6) x 2
In the equation, C L is the crystal load capacitance. So, for a crystal with a 16 pF load capacitance, two 20 pF [(16-6) x 2] capacitors should be ud.
Spread Spectrum Profile
The ICS7152 low EMI clock generator us a triangular frequency modulation profile for optimal dow
n stream tracking of zero delay buffers and other PLL devices. The frequency modulation amplitude is constant with variations of the input frequency.
Spread Spectrum Clock Generator
Absolute Maximum Ratings
Stress above the ratings listed below can cau permanent damage to the ICS7152. The ratings, which are standard values for ICS commercially rated parts, are stress ratings only. Functional operation of the device at the or any other conditions above tho indicated in the operational ctions of the
specifications is not implied. Exposure to absolute maximum rating conditions for extended periods can affect product reliability. Electrical parameters are guaranteed only over the recommended operating temperature range.
Recommended Operation Conditions
Item
Rating
Supply Voltage, VDD
7 V
All Inputs and Outputs (referenced to GND)-0.5 V to VDD+0.5 V Ambient Operating Temperature -40 to +85°C Storage Temperature -55 to +125°C Junction Temperature -40 to +125°C Soldering Temperature 260°C
Overshoot (V IOVER )VDD + 1.0 V (t OVER < 50 ns) max Undershoot (V IUNDER )
GND - 1.0 V (t UNDER < 50 ns) min
Parameter
Min.
Typ.
Max.
Units
Ambient Operating Temperature
-40+85°C Power Supply Voltage (measured in respect to GND)
+3.0
3.3
3.6
V
Spread Spectrum Clock Generator
DC Electrical Characteristics
Unless stated otherwi, VDD = 3.3 V ±0.3 V, Ambient Temperature -40 to +85°C
Parameter Symbol Conditions Min.Typ.Max.Units Operating Voltage VDD 3.0 3.3 3.6V
Supply Current IDD No load, at 3.3 V1428mA Input High Voltage V IH SEL, FREQ, XENS VDD x 0.8VDD + 0.3V
XIN, Input slew rate
3 V/ns, 16.6 to 100
MHz
VDD x 0.8VDD + 0.3V
XIN, Input slew rate
3 V/ns, 100 to 134
MHz
VDD x 0.9VDD + 0.3V
Input Low Voltage V IL SEL, FREQ, XENS GND VDD x 0.20V
XIN, Input slew rate
3 V/ns, 16.6 to 100
MHz
GND VDD x 0.20V
XIN, Input slew rate
3 V/ns, 100 to 134
MHz
GND VDD x 0.10V
Output High Voltage V OH CKOUT, I OH = -4 mA VDD - 0.5VDD V
Output Low Voltage V OL CKOUT, I OL = 4 mA GND0.4V
Input Capacitance C IN XIN, SEL, XENS16pF
Load Capacitance C L CKOUT, 16.6 to 67
MHz
15pF
CKOUT, 67 to 100
MHz
10pF
CKOUT, 100 to 134
MHz
7pF
Output Impedance Z O CKOUT, 16.6 to 134
MHz 25Ω
Spread Spectrum Clock Generator
AC Electrical Characteristics
Unless stated otherwi, VDD = 3.3 V ±0.3 V, Ambient Temperature -40 to +85° C
Parameter Symbol Conditions Min.Typ.Max.Units Input Crystal Frequency16.640MHz Input Clock Frequency f IN ICS7152-01, -1116.667MHz
ICS7152-02, -1240134MHz Output Frequency f OUT CKOUT,
ICS7152-01, -11
16.667MHz
CKOUT,
ICS7152-02, -12
40134MHz Input Clock Duty Cycle t DCI XIN, 16.6 to 100 MHz405060%
XIN, 100 to 134 MHz455055% Output Clock Duty Cycle t DCC CKOUT, 1.5 V4060% Output Slew Rate CKOUT, 0.4 to 2.4 V,
CL = 15 pF
0.5 3.0V/ns
Cycle to Cycle Jitter t JC No load, spread off,
ICS7151-01, -02
150ps
No load, spread off,
ICS7151-11, -12
250ps
Power-up Time PLL lock-time from
power-up to 1% of final
value
25ms Modulation Frequency f MOD CKOUT33kHz
