FUJITSU MICROELECTRONICS
DATA SHEET
DS04-29129-2E
Spread Spectrum Clock Generator
MB88154A
MB88154A-101/102/103/111/112/113
■
DESCRIPTION
MB88154A is a clock generator for EMI (Electro Magnetic Interference) reduction. The peak of unnecessary
radiation noise (EMI) can be attenuated by making the oscillation frequency slightly modulate periodically with
the internal modulator. It corresponds to both of the center spread which modulates input frequency as Middle
Centered and down spread which modulates so as not to exceed input frequency.
■
FEATURE
• Input frequency : 16.6 MHz to 80 MHz
• Output frequency: 16.6 MHz to 80 MHz (One time input frequency)
• Modulation rate can select from
±
0.5%,
±
1.0%,
±
1.5% or
−
1.0%,
−
2.0%,
−
3.0%. (For center spread / down
spread.)
• Equipped with crystal oscillation circuit: Range of oscillation 16.6 MHz to 48 MHz
• The external clock can be input: 16.6 MHz to 80 MHz
• Modulation clock output duty : 40% to 60%
• Modulation clock cycle-cycle jitter : Less than 100 ps
• Low current consumption by CMOS process : 5.0 mA (24 MHz : Typ-sample, no load)
• Power supply voltage : 3.3 V
±
0.3 V
• Operating temperature :
−
40
°C
to
+85 °C
• Package : SOP 8-pin
Copyright©2007-2009 FUJITSU MICROELECTRONICS LIMITED All rights reserved
2009.6
MB88154A
■
PRODUCT LINEUP
MB88154A has two kinds of input frequency, and three kinds of modulation type (center/down spread), total six
line-ups.
Product
Input/Output frequency
Modulation type
MB88154A-101
MB88154A-102
MB88154A-103
MB88154A-111
MB88154A-112
MB88154A-113
50 MHz to 80 MHz
33 MHz to 67 MHz
16.6 MHz to 40 MHz
50 MHz to 80 MHz
33 MHz to 67 MHz
16.6 MHz to 40 MHz
Center spread
Down spread
■
PIN ASSIGNMENT
TOP VIEW
CKOUT 1
V
DD
2
V
SS
3
XIN 4
MB88154A
8 SEL1
7 REFOUT
6 SEL0
5 XOUT
FPT-8P-M02
■
PIN DESCRIPTION
Pin name
CKOUT
V
DD
V
SS
XIN
XOUT
SEL0
REFOUT
SEL1
I/O
O
⎯
⎯
I
O
I
O
I
Pin no.
1
2
3
4
5
6
7
8
Modulated clock output pin
Power supply voltage pin
GND pin
Crystal resonator connection pin/clock input pin
Crystal resonator connection pin
Modulation rate setting pin
Non-modulated clock output pin
Modulation rate setting pin
Description
2
DS04-29129-2E
MB88154A
■
I/O CIRCUIT TYPE
Pin
SEL0
SEL1
Circuit type
Remarks
CMOS hysteresis input
CKOUT
REFOUT
• CMOS output
• I
OL
=
3 mA
Note : For XIN and XOUT pins, refer to “■ OSCILLATION CIRCUIT”
DS04-29129-2E
3
MB88154A
■
HANDLING DEVICES
Preventing Latch-up
A latch-up can occur if, on this device, (a) a voltage higher than V
DD
or a voltage lower than V
SS
is applied to an
input or output pin or (b) a voltage higher than the rating is applied between V
DD
pin and V
SS
pin. The latch-up,
if it occurs, significantly increases the power supply current and may cause thermal destruction of an element.
When you use this device, be very careful not to exceed the maximum rating.
Handling unused pins
Do not leave an unused input pin open, since it may cause a malfunction. Handle by, using a pull-up or
pull-down resistor.
Unused output pin should be opened.
The attention when the external clock is used
Input the clock to XIN pin, and XOUT pin should be opened when you use the external clock.
Please pay attention so that an overshoot and an undershoot do not occur to an input clock of XIN pin.
Power supply pins
Please design connecting the power supply pin of this device by as low impedance as possible from the current
supply source.
We recommend connecting electrolytic capacitor (about 10
μF)
and the ceramic capacitor (about 0.01
μF)
in
parallel between V
SS
pin and V
DD
pin near the device, as a bypass capacitor.
Oscillation circuit
Noise near the XIN and XOUT pins may cause the device to malfunction. Design printed circuit boards so that
electric wiring of XIN or XOUT pin and the resonator do not intersect other wiring.
Design the printed circuit board that surrounds the XIN and XOUT pins with ground.
4
DS04-29129-2E
MB88154A
■
BLOCK DIAGRAM
V
DD
2
SEL1
8
1
Modulation rate
setting
6
CKOUT
Modulation
clock output
PLL block
SEL0
XOUT
Reference
clock
5
Reference clock output
4
XIN
R
f
=
1 MΩ
3
V
SS
7
REFOUT
1
−
M
Phase
compare
Charge
pump
V/I
conversion
IDAC
ICO
Modulation
Reference
clock
1
−
N
Loop filter
Clock
output
1
−
L
Modulation
logic
Modulation
rate setting/
Modulation
enable setting
MB88154A PLL block
A glitchless IDAC (current output D/A converter) provides precise modulation, thereby dramatically
reducing EMI.
DS04-29129-2E
5
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