CY5057
Document Number: 38-07363 Rev. *C
Page 4 of 10
Power Management Features
CY5057 contains Flash programmable PD# (active LOW) and
OE (active HIGH) functions. If power down mode is selected
(PD# = 0), the oscillator and PLL are placed in a low supply
current standby mode and the output is tri-stated and weakly
pulled low. The oscillator and PLL circuits must relock when the
part leaves power down mode. If output enable mode is selected
(OE = 0), the output is tri-stated and weakly pulled low. In this
mode the oscillator and PLL circuits continue to operate allowing
a rapid return to normal operation when the output is enabled.
In addition, the PD# and OE modes may be programmed to
occur synchronously or asynchronously with respect to the
output signal. When the asynchronous setting is used, the power
down or output disable occurs immediately (allowing for logic
delays) irrespective of the position in the clock cycle. However,
when the synchronous setting is used, the part waits for a falling
edge at the output before power down or output enable signal
initiated, thus preventing output glitches. In asynchronous or
synchronous
setting,
the
output
is
always
enabled
synchronously by waiting for the next falling edge of the output.
Spread Spectrum
CY5057 contains spread spectrum with Flash programmable
spread percentage and modulation frequency. Center spread
nonlinear “Hershey kiss” modulation is obtained. Spread
percentage is programmed to values between +0.250% and
+2.00%, in 0.25% intervals. Only one spread profile (for one
specific percentage spread and for one output frequency) may
be programmed into the device at a time.
CY5057 has a spread spectrum on and off function. The spread
spectrum is enabled or disabled through an external pin. Timing
this feature is explained in Switching Waveforms on page 7.
Figure 1. Crystal Oscillator Tuning Circuit
Table 3. Crystal Oscillator Tuning Cap Values
Bit[1]
Capacitance per Bit (pF)
C7 (MSB)
24.32
C6
12.16
C5
6.08
C4
3.04
C3
1.52
C2
0.76
C1
0.38
C0 (LSB)
0.19
XOUT
XIN
CXIN
CXOUT
C0
C1
C2
C3
C4
C5
C6
C7
C7
C6
C5
C4
C3
C2
C1
C0
RF
Note
1. CXIN, CXOUT, and parasitic capacitance due to fixture and package should be included when calculating the total capacitance.
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