tc7mbl3257cft TOSHIBA Semiconductor CORPORATION, tc7mbl3257cft Datasheet - Page 8

• Manufacturer Part Number: tc7mbl3257cft
• Description: 4-bit 1-of-2 Multiplexer/demultiplexer
• Manufacturer: TOSHIBA Semiconductor CORPORATION

Rise and Fall Times (tr / tf) of the TC7MBL3257C I/O Signals
The tr(out) and tf(out) values of the output signals are affected by the CR time constant of the input, which consists of
the switch terminal capacitance (C
In practice, the tr(out) and tf(out) values are also affected by the circuit’s capacitance and resistance components other
than those of the TC7MBL3257C.
The tr(out) / tf(out) values can be approximated as follows. (Figure 3 shows the test circuit.)
Calculation example:
Calculation conditions:
tr(out) / tf(out) (approx) = - ( C
tr(out) (approx) = - ( 8 + 15 )E-12 ･ ( 120 + 8.5) ･ ln ( ( ( 3.0 - 0 ) – 1.5 ) / ( 3.0 – 0 ) )
V
Output of the previous IC = digital (i.e., high-level voltage = V
CC
= 3.0 V , C
≈ 2.1 ns
Previous IC
R
DRIVE
R
L
DRIVE
= output impedance of the previous IC
= 15 pF , R
A/Bn
DRIVE
I/O
+ C
I/O
= 120 Ω (output impedance of the previous IC), V
) and the on-resistance (R
L
TC7MBL3257C
(Switch On)
Previous IC
R
) ･ (R
DRIVE
Figure 3 Test Circuit
C
R
I/O
ON
R
DRIVE+
DRIVE
where, R
= output impedance of the previous IC
R
ON
Bn/A
DRIVE
8
) ･ ln ( ( ( V
CC
ON
is the output impedance of the previous-stage circuit.
Parameter
; low-level voltage = GND)
) of the input.
Measure
Measure
V
M
OH
– V
Waveform generated without the TC7MBL3257C
Waveform generated with the TC7MBL3257C added
TC7MBL3257CFT/FK/FTG
OL
3.3 ± 0.3 V
) – V
V
CC
tr(out)
/ 2
M
M
V
) / ( V
= 1.5 V (V
M
OH
– V
2.5 ± 0.2 V
V
CC
V
CC
OL
CC
/ 2)
tf(out)
/ 2
) )
2008-07-17
V
M
V
GND
CC
1.8 ± 0.15 V
V
V
V
CC
OH
OL
/ 2