FUJITSU SEMICONDUCTOR
DATA SHEET
DS04-29119-2E
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 clock output pin (REFOUT) as well as a modulated clock 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%
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
•
•
•
•
Copyright©2005-2006 FUJITSU LIMITED All rights reserved
MB88155
■
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) .
MB88155-M T F
Input frequency range,
With/without ENS/XPD
Multiplied
0 : 12.5 MHz to 25.0 MHz, With ENS, Without XPD
by 1
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
0 : 12.5 MHz to 20.0 MHz, With ENS, Without XPD
by 4
2 : 12.5 MHz to 20.0 MHz, Without ENS, With XPD
→
0 : Down spread, 1 : Center spread
→
1 : Multiplied by 1, 4 : Multiplied by 4
→
Spread type
Multiplication rate setting
Line-up of MB88155
Product
MB88155-100
MB88155-101
MB88155-102
MB88155-103
MB88155-110
MB88155-111
MB88155-112
MB88155-113
MB88155-400
MB88155-402
MB88155-410
MB88155-412
Input frequency
12.5 MHz to 25 MHz
25 MHz to 50 MHz
12.5 MHz to 25 MHz
25 MHz to 50 MHz
12.5 MHz to 25 MHz
25 MHz to 50 MHz
12.5 MHz to 25 MHz
25 MHz to 50 MHz
Multiplication
rate
Output
frequency
Modulation Modulation
Power
type
enable pin down pin
Yes
Down
spread
No
Yes
No
Yes
No
Yes
No
Yes
No
Multiplied by 1
The same as
input frequency
Yes
Center
spread
No
Down
spread
Center
spread
Yes
No
Yes
No
12.5 MHz to 20 MHz Multiplied by 4
50 MHz to
80 MHz
2
MB88155
■
PIN ASSIGNMENT
XIN 1
XOUT 2
ENS 3
SEL 4
8 V
DD
XIN 1
XOUT 2
XPD 3
SEL 4
8 V
DD
MB88155
-xx0
-xx1
7 CKOUT
6 V
SS
5 REFOUT
MB88155
-xx2
-xx3
7 CKOUT
6 V
SS
5 REFOUT
FPT-8P-M07
■
PIN DESCRIPTION
Pin name
XIN
XOUT
ENS/XPD
I/O
I
O
I
Pin no.
1
2
3
Description
Connection pin of resonator/clock input pin
Connection pin of resonator
Modulation enable pin/power down pin
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%
Non-modulated clock output pin
This pin becomes to“L” at power-down.
GND Pin
Modulated clock output pin
This pin becomes to“L” at power-down.
Power supply voltage pin
SEL
I
4
REFOUT
V
SS
CKOUT
V
DD
O
⎯
O
⎯
5
6
7
8
3
MB88155
■
I/O CIRCUIT TYPE
Pin
Circuit type
Remarks
CMOS hysteresis input
SEL,
XPD
CMOS hysteresis input with pull-up
resistor of 50 kΩ (Typ)
50 kΩ
ENS
• CMOS output
• I
OL
=
3 mA
• “L” output at power-down
REFOUT
(Continued)
4
MB88155
(Continued)
Pin
Circuit type
Remarks
• CMOS output
• I
OL
=
4 mA
• “L” output at power-down
CKOUT
Note: For XIN pin and XOUT pin, refer to “■ OSCILLATION CIRCUIT”.
5
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