Renesas TPS-1 User Manual

TPS-1 User’s Manual: Hardware 9. Clock Circuit
R19UH0081ED0107 Rev. 1.07 page 57 of 86
Jul 30, 2018
9.2. External clock source
“Fast Start Up” applications require a maximum clock startup time of 20 ms. This cannot not be
realized with a crystal. For “Fast Start Up” applications an external oscillator is recommended.
It is possible to use an external clock source instead of a quartz crystal as clock input for XCLK1 (Pin N11) as well. In this case the XCLK2 has to be
left unconnected and the port XCLK1 has to fulfil the following requirements:
Table 9-2: Parameter for external oscillator as clock source
Description
Parameter
Min
Typ
Max
Unit
External clock source frequency
f
IN
1)
25
1)
MHz
XCLK1 high level voltage
V
HL
2
3,3
VDDACB (H14)
V
XCLK1 low level voltage
V
IL
0
-
0,8
V
XCLK1 rise or fall time
t
RFC
0
1
4
ns
XCLK1 high or low time
t
W
16
2)
20
2)
24
2)
ns
XCLK1 jitter tolerance
t
JIT
20
ps (RMS)
XCLK1 duty cycle
DuCy
40
50
60
%
1) +/- 50 ppm over all (lifetime and temperature)
2) t
W
was calculated at f
IN(TYP)
=25 MHz, e.g. t
w(MIN) = 10 *
(DuCy
(MIN)
/ f
IN(TYP)
)
Recommended external crystal oscillators:
• Epson SG-210 STF 25.000000 L MHz (85
O
C)
• Epson SG-210 STF 25.000000 Y MHz (105
O
C)
PCB layout hints:
• Place the input and output pins of the oscillator and the resistor and external component close to each other, and keep
wiring as short as possible.
• Make the wiring between the ground side of the capacitor and the ground pin of the TPS-1 as short and as thick as
possible.
• Keep the lead wire of the “crystal” and capacitor as short as possible, and fix the “crystal” and the capacitor to the
printed circuit board to keep the influence of mechanical vibrations to a minimum.
• Layout the external constant portions so that it is surrounded by GND as far as possible.
XCLK
1
(N11)
TPS-1
GND pattern
XCLK2
(P11)
Circuit board
Figure 9-2: Ground pattern for crystal unit

Renesas TPS-1 Specifications

General

Brand	Renesas
Model	TPS-1
Category	Controller
Language	English