Technical Note
BU4015B,BU4015BF,BU4021B,BU4021BF,
BU4094BC,BU4094BCF,BU4094BCFV,BU4538B,BU4028B
13/17
www.rohm.com
2009.06 - Rev.A
2009 ROHM Co., Ltd. All rights reserved.
1
2
4
5
6
7
14
13
12
9
P8
P5
DS
CLOCK
P/S
Q7
11
3
10
P6
Q6
Q8
P4
P3
P2
P1
8
VSS
15
P7
16
VDD
P8
Q6
Q8
P4
P3
P2
P1
P7
P6
Q5
Q7
DS
CLOCK
P/S
●Description of BU4021B series model
Function: 8-stage static shift register
1) Description of operation
BU4021B is an 8-bit static shift register capable of parallel input/series output and series input/series output. In parallel
operation, DS (data) being asynchronous with the clock is inputted into each F/F and obtained at output.
In series operation, DS (data) is triggered by clock.
When P/S input level is “H”, parallel operation is effective, and when P/S input level is “L”, series operation is effective.
PIN arrangement
Block diagram
Truth table
●Description of BU4094BC series model
Function: Dual 4-bit static shift register
1) Description of operation
BU4094BC is an 8-stage shift/store register provided in each stage with a data latch with 3-state output. Data read into
shift register is read into the latch during the fall time of asynchronous STROBE input, and in the data transfer mode,
output can be held. Data is passed through the latch and outputted when the STROBE is in “H” level. Because the parallel
output becomes high impedance when the OUTPUT ENABLE terminal is set to “L” level by 3-state, the parallel output can
be connected directly with the 8-bit pass line.
PIN arrangement
PIN description
PIN No.
Symbol
I/O
Function
1
P8
I
Parallel data input 8
2
Q6
O
Output 6
3
Q8
O
Output 8
4
P4
I
Parallel data input 4
5
P3
I
Parallel data input 3
6
P2
I
Parallel data input 2
7
P1
I
Parallel data input 1
8
VSS
―
Power supply(-)
9
P/S
I
Parallel/Serial
10
CLOCK
I
Clock input
11
DS
I
Serial data input
12
Q7
O
Output 7
13
P5
I
Parallel data input 5
14
P6
I
Parallel data input 6
15
P7
I
Parallel data input 7
16
VDD
―
Power supply (+)
PIN description
PIN No.
Symbol
I/O
Function
1
STROBE
I
Latch input
2
SERIALIN
I
Data input
3
CLOCK
I
Clock input
4
Q1
O
Parallel data input Q1
5
Q2
O
Parallel data input Q2
6
Q3
O
Parallel data input Q3
7
Q4
O
Parallel data input Q4
8
VSS
―
Power supply(-)
9
QS
O
Serial data output QS
10
Q’S
O
Serial data output Q’S
11
Q8
O
Parallel data output Q8
12
Q7
O
Parallel data output Q7
13
Q6
O
Parallel data output Q6
14
Q5
O
Parallel data output Q5
15
ENABLE
I
Output enable
16
VDD
―
Power supply (+)
CLOCK
D
RESET
Q0
Q1
Q2
Q3
X
H
L
LLL
No Change
X
H
LL
L
LQ0
H
Q1
Q2
Q0
Q1
Q2
CLOCK
DS
P/S
Dm
Qm*
X
XH
L
H
L
HH
X:Don't Care
*:Q6,Q7,Q8は外部
X:Don't Care
1
2
4
5
6
7
14
13
12
9
STROBE
Q6
Q8
Q'S
QS
Q7
11
3
10
Q5
SERIAL
CLOCK
Q1
Q2
Q3
Q4
8
VSS
15
OUTPUT
16
VDD
IN
ENABLE
STROBE
SERIA
IN
CLOCK
Q1
Q2
Q3
Q4
Q6
Q8
Q'S
QS
Q7
Q5
OUTPUT
ENABLE
CLOCK
D
C
Q
D
C
Q
D
C
Q
D
C
Q
D
C
Q
D
C
D
C
Q
D
C
Q
P/S
Q
P1
P2
P3
P4
P5
P6
P7
P8
*:Q6,Q7,Q8:
outside