TC4469 TelCom Semiconductor, TC4469 Datasheet - Page 4

• Manufacturer Part Number: TC4469
• Description: (TC4467 - TC4469) LOGIC-INPUT CMOS QUAD DRIVERS
• Manufacturer: TelCom Semiconductor

Supply Bypassing
large capacitive loads quickly. For example, charging a
1000 pF load to 18V in 25nsec requires 0.72A from the
device's power supply.
quency range, a 1 F film capacitor in parallel with one or two
low-inductance 0.1 F ceramic disk capacitors with short
lead lengths (<0.5 in.) normally provide adequate bypass-
ing.
Grounding
Potential drops developed in common ground impedances
from input to output will appear as negative feedback and
degrade switching speed characteristics. Instead, individual
ground returns for input and output circuits, or a ground
plane, should be used.
Input Stage
cent supply current. The N-channel MOSFET input stage
transistor drives a 2.5 mA current source load. With logic "0"
outputs, maximum quiescent supply current is 4 mA. Logic
"1" output level signals reduce quiescent current to 1.4 mA
maximum. Unused driver inputs must be connected to V
or V
outputs.
provides clean transitions and minimizes output stage cur-
rent spiking when changing states. Input voltage thresholds
are approximately 1.5V, making any voltage greater than
1.5V up to V
over this range.
Power Dissipation
versus capacitive load characteristic curves will aid in deter-
mining power dissipation calculations. TelCom Semicon-
ductor's CMOS drivers have greatly reduced quiescent DC
power consumption.
type, influence package power dissipation. Given power
dissipation and package thermal resistance, the maximum
ambient operating temperature is easily calculated. The 14-
pin plastic package junction-to-ambient thermal resistance
is 83.3 C/W. At +70 C, the package is rated at 800mW
maximum dissipation. Maximum allowable chip tempera-
ture is +150 C.
4-264
TC4467
TC4468
TC4469
Large currents are required to charge and discharge
To guarantee low supply impedance over a wide fre-
The TC4467 and TC4469 contain inverting drivers.
The input voltage level changes the no-load or quies-
The drivers are designed with 50 mV of hysteresis. This
The supply current versus frequency and supply current
Input signal duty cycle, power supply voltage and load
SS
. Minimum power dissipation occurs for logic "1"
DD
a logic 1 input . Input current is less than 1 A
DD
dissipation:
gates), is a direct function of frequency, capacitive load, and
supply voltage. The power dissipation is:
where: f = Switching frequency
enced loads is a function of duty cycle, load current, and
load voltage. The power dissipation is:
where: D = Duty cycle
enced loads is a function of duty cycle, load current, and
output voltage. The power dissipation is:
where: f = Switching frequency
duty cycle. Logic HIGH outputs result in a lower power
dissipation mode, with only 0.6 mA total current drain (all
devices driven). Logic LOW outputs raise the current to 4 mA
maximum. The quiescent power dissipation is:
where: I
Three components make up total package power
(1) Load-caused dissipation (P
(2) Quiescent power (P
(3) Transition power (P
A capacitive-load-caused dissipation (driving MOSFET
P
A resistive-load-caused dissipation for ground-refer-
P
A resistive-load-caused dissipation for supply-refer-
P
Quiescent power dissipation depends on input signal
P
L
L
L
Q
= f C V
= D (V
= D V
= V
C = Capacitive load
V
V
V
I
V
I
I
D = Duty cycle
V
L
L
H
L
S
S
L
O
S
= Load current.
= Load current.
= Quiescent current with all outputs HIGH
= Quiescent current with all outputs LOW
= Load voltage
S
= Supply voltage.
= Supply voltage
=Supply voltage.
= Device output voltage
O
(4 mA max)
(0.6 mA max)
(D (IH) + (1–D)I
S
S
I
2
– V
L
,
,
L
) I
TELCOM SEMICONDUCTOR, INC.
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LOGIC-INPUT CMOS
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QUAD DRIVERS
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