Datasheet

32KX
CK0 CK1CK1
032-071
TPS65950
SWCS032E–OCTOBER 2008–REVISED JANUARY 2011 www.ti.com
Table 12-7 lists the electrical constraints required by the 32-kHz input square- or sine-wave clock used.
Table 12-7. 32-kHz Input Square- or Sine-Wave Clock Source Electrical Characteristics
Name Parameter Description Min Typ Max Unit
f Frequency 32.768 kHz
C
I
Input capacitance 35 pF
C
FI
On-chip foot capacitance to GND on each input (see Figure 12-7, Figure 12-8, and 10
pF
Figure 12-9)
V
PP
Square-/sine-wave amplitude in bypass mode or not 1.8
(1)
V
V
IH
Voltage input high, square wave in bypass mode 0.8 V
V
IL
Voltage input low, square wave in bypass mode 0.6 V
(1) Bypass input maximum voltage is the same as the maximum voltage provided for the I/O interface.
Table 12-8 lists the input requirements of the 32-kHz square-wave input clock.
Table 12-8. 32-kHz Square-Wave Input Clock Source Timing Requirements
Name Parameter Description Min Typ Max Unit
CK0 1/t
C(32KHZ)
Frequency, 32 kHz 32.768 MHz
CK1 t
W(32KHZ)
Pulse duration, 32 kHz low or high 0.45*t
C(32KHZ)
0.55*t
C(32KHZ)
μs
CK3 t
R(32KHZ)
Rise time, 32 kHz
(1)
0.1*t
C(32KHZ)
μs
CK4 t
F(32KHZ)
Fall time, 32 kHz
(1)
0.1*t
C(32KHZ)
μs
(1) The capacitive load is 30 pF.
Figure 12-10 shows the timing of the 32-kHz square- or sine-wave input clock.
Figure 12-10. 32-kHz Square- or Sine-Wave Input Clock
12.3 Output Clock Specifications
The TPS65950 provides two output clocks:
• 32KCLKOUT
• HFCLKOUT
12.3.1 32KCLKOUT Output Clock
Figure 12-11 is a block diagram of the 32.768-kHz clock output.
140 Clock Specifications Copyright © 2008–2011, Texas Instruments Incorporated
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