DS04-29119-1E
FUJITSU SEMICONDUCTOR
DATA SHEET
Spread Spectrum Clock Generator
MB88155
DESCRIPTION
MB88155 is a clock generator for EMI (Electro Magnetic Interference) reduction. The peak of unnecessary radi-
ation noise (EMI) can be attenuated by making the oscillation frequency slightly modulate periodically with the
internal modulator. For modulation, the MB88155 supports both center-spreading and down-spreading. It has a
non-modulated output pin (REFOUT) as well as a modulated output pin (CKOUT) .
FEATURES
Input frequency :
12.5 MHz to 50 MHz (Multiplied by 1)
12.5 MHz to 20 MHz (Multiplied by 4)
Output frequency : CKOUT
12.5 MHz to 80 MHz
REFOUT
The same as input frequency (not multiplied)
Modulation rate :
0.5
%
,
1.0
%
(center spread) ,
-
1.0
%
,
-
2.0
%
(Down spread)
Equipped with oscillation circuit : range of oscillation 12.5 MHz to 40 MHz (Fundamental oscillation)
40 MHz to 48 MHz (3rd overtone)
Modulation clock output Duty : 40
%
to 60
%
(Continued)
PACKAGE
8-pin plastic TSSOP
(FPT-8P-M05)
MB88155
2
(Continued)
Modulation clock cycle
-
cycle jitter : MB88155-1xx
12.5 MHz to 20 MHz
less than 150 ps
MB88155-1xx
20 MHz to 50 MHz
less than 100 ps
MB88155-4xx
less than 200 ps
Low current consumption by CMOS process : 5 mA (24 MHz : Typ-sample, no load)
Power supply voltage : 3.3 V
0.3 V
Operating temperature :
-
40
C to
+
85
C
Package : 8-pin plastic TSSOP
MB88155
3
PRODUCT LINEUP
The MB88155 is available in different models : 2 models different in multiplier (
1 and
4) , 2 in modulation
type (center-spreading and down-spreading) , 2 in input frequency range at a multiplier of 1 (12.5 MHz to
25 MHz and 25 MHz to 50 MHz) , and 1 in input frequency range at a multiplier of 4 (12.5 MHz to 20 MHz) .
The MB88155 is also available in two versions : modulation-on/off selectable version (with ENS pin) and power-
down function built-in version (with XPD pin) .
Line-up of MB88155
Product
Input frequency
Multiplication
rate
Output
frequency
Modulation
type
Modulation
enable pin
Power
down pin
MB88155-100
12.5 MHz to 25 MHz
Multiplied by 1
The same as
input frequency
Down
spread
Yes
No
MB88155-101
25 MHz to 50 MHz
MB88155-102
12.5 MHz to 25 MHz
No
Yes
MB88155-103
25 MHz to 50 MHz
MB88155-110
12.5 MHz to 25 MHz
Center
spread
Yes
No
MB88155-111
25 MHz to 50 MHz
MB88155-112
12.5 MHz to 25 MHz
No
Yes
MB88155-113
25 MHz to 50 MHz
MB88155-400
12.5 MHz to 20 MHz Multiplied by 4
50 MHz to
80 MHz
Down
spread
Yes
No
MB88155-402
No
Yes
MB88155-410
Center
spread
Yes
No
MB88155-412
No
Yes
MB88155-M T F
Input frequency range,
With/without ENS/XPD
Multiplied
by 1
0 : 12.5 MHz to 25.0 MHz, With ENS, Without XPD
1 : 25.0 MHz to 50.0 MHz, With ENS, Without XPD
2 : 12.5 MHz to 25.0 MHz, Without ENS, With XPD
3 : 25.0 MHz to 50.0 MHz, Without ENS, With XPD
Multiplied
by 4
0 : 12.5 MHz to 20.0 MHz, With ENS, Without XPD
2 : 12.5 MHz to 20.0 MHz, Without ENS, With XPD
Spread type
0 : Down spread, 1 : Center spread
Multiplication rate setting
1 : Multiplied by 1, 4 : Multiplied by 4
MB88155
4
PIN ASSIGNMENT
PIN DESCRIPTION
Pin name
I/O
Pin no.
Description
XIN
I
1
Connection pin of resonator/clock input pin
XOUT
O
2
Connection pin of resonator
ENS/XPD
I
3
Modulation enable pin/power down pin
SEL
I
4
Modulation rate setting pin
Down spread, SEL
=
"L" : Modulation rate
-
1.0
%
Down spread, SEL
=
"H" : Modulation rate
-
2.0
%
Down spread, SEL
=
"L" : Modulation rate
0.5
%
Down spread, SEL
=
"H" : Modulation rate
1.0
%
REFOUT
O
5
Non-modulated clock output pin
This pin becomes to"L" at power-down.
V
SS
6
GND Pin
CKOUT
O
7
Modulated clock output pin
This pin becomes to"L" at power-down.
V
DD
8
Power supply voltage pin
1
2
3
4
8
7
6
5
XIN
XOUT
ENS
SEL
V
DD
CKOUT
V
SS
REFOUT
1
2
3
4
8
7
6
5
XIN
XOUT
XPD
SEL
V
DD
CKOUT
V
SS
REFOUT
MB88155
-xx0
-xx1
MB88155
-xx2
-xx3
FPT-8P-M05
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