Datasheet

C4
C3
XCLKOUT
(B)
XCLKIN
(A)
C5
C9
C10
C1
C8
C6
TMS320F28027, TMS320F28026, TMS320F28023, TMS320F28022
TMS320F28021, TMS320F28020, TMS320F280200
www.ti.com SPRS523J –NOVEMBER 2008–REVISED OCTOBER 2013
6.8 Clock Requirements and Characteristics
Table 6-10. XCLKIN Timing Requirements - PLL Enabled
NO. MIN MAX UNIT
C9 t
f(CI)
Fall time, XCLKIN 6 ns
C10 t
r(CI)
Rise time, XCLKIN 6 ns
C11 t
w(CIL)
Pulse duration, XCLKIN low as a percentage of t
c(OSCCLK)
45 55 %
C12 t
w(CIH)
Pulse duration, XCLKIN high as a percentage of t
c(OSCCLK)
45 55 %
Table 6-11. XCLKIN Timing Requirements - PLL Disabled
NO. MIN MAX UNIT
C9 t
f(CI)
Fall time, XCLKIN Up to 20 MHz 6 ns
20 MHz to 30 MHz 2
C10 t
r(CI)
Rise time, XCLKIN Up to 20 MHz 6 ns
20 MHz to 30 MHz 2
C11 t
w(CIL)
Pulse duration, XCLKIN low as a percentage of t
c(OSCCLK)
45 55 %
C12 t
w(CIH)
Pulse duration, XCLKIN high as a percentage of t
c(OSCCLK)
45 55 %
The possible configuration modes are shown in Table 3-19.
Table 6-12. XCLKOUT Switching Characteristics (PLL Bypassed or Enabled)
(1) (2)
over recommended operating conditions (unless otherwise noted)
NO. PARAMETER MIN TYP MAX UNIT
C3 t
f(XCO)
Fall time, XCLKOUT 11 ns
C4 t
r(XCO)
Rise time, XCLKOUT 11 ns
C5 t
w(XCOL)
Pulse duration, XCLKOUT low H – 2 H + 2 ns
C6 t
w(XCOH)
Pulse duration, XCLKOUT high H – 2 H + 2 ns
(1) A load of 40 pF is assumed for these parameters.
(2) H = 0.5t
c(XCO)
A. The relationship of XCLKIN to XCLKOUT depends on the divide factor chosen. The waveform relationship shown is
intended to illustrate the timing parameters only and may differ based on actual configuration.
B. XCLKOUT configured to reflect SYSCLKOUT.
Figure 6-6. Clock Timing
Copyright © 2008–2013, Texas Instruments Incorporated Electrical Specifications 91
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