LH0094CD National Semiconductor, LH0094CD Datasheet - Page 3

• Manufacturer Part Number: LH0094CD
• Description: IC CONVERTER MULTIFUNCTN 16DIP
• Manufacturer: National Semiconductor
• Type: Converterr

Specifications of LH0094CD

• Applications: Control systems
• Mounting Type: Through Hole
• Package / Case: *
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Voltage - Supply, Analog: -
• Voltage - Supply, Digital: -
• Other names: *LH0094CD

Applications Information
GENERAL INFORMATION
Power supply bypass capacitors (0 1 F) are recommended
for all applications
The LH0094 series is designed for positive input signals
only However negative input up to the supply voltage will
not damage the device
A clamp diode ( Figure 1 ) is recommended for those applica-
tions in which the inputs may be subjected to open circuit or
negative input signals
For basic applications (multiply divide square square root)
it is possible to use the device without any external adjust-
ments or components Two matched resistors are provided
internally to set m for square or square root
When using external resistors to set m such resistors
should be as close to the device as possible
SELECTION OF RESISTORS TO SET m
Internal Matched Resistors
R
100
(a) m
(b) m
External Resistors
The exponent is set by 2 external resistors or it may be
continuously varied by a single trim pot (R1
(a) m
A
and R
e
e
e
g
10% but matched to 0 1%
2
0 5
1
No external resistors required strap as indicated
B
are matched internal resistors They are
a
TL H 5695– 3
R2
TL H 5695 – 2
s
500
3
(b) m
(c) m
ACCURACY (ERROR)
The accuracy of the LH0094 is specified for both externally
adjusted and unadjusted cases
Although it is customary to specify the errors in percent of
full-scale (10V) it is seen from the typical performance
curves that the actual errors are in percent of reading Thus
the specified errors are overly conservative for small input
voltages An example of this is the LH0094 used in the mul-
tiplication mode The specified typical error is 0 25% of full-
scale (25 mV) As seen from the curve the unadjusted error
is
inputs up to 1V Note also that if either the multiplicand or
the multiplier is at less than 10V (5V for example) the unad-
justed error is less Thus the errors specified are at full-
scale the worst case
The LH0094 is designed such that the user is able to exter-
nally adjust the gain and offset of the device thus trim out
all of the errors of conversion In most applications the gain
adjustment is the only external trim needed for super accu-
racy except in division mode where a denominator offset
adjust is needed for small denominator voltages
EXPONENTS
The LH0094 is capable of performing roots to 0 1 and pow-
ers up to 10 However care should be taken when applying
these exponent otherwise results may be misinterpreted
For example consider the
0 001 raised to 0 1 power is 0 5011 0 1 raised to the 0 1
power is 0 7943 and 10 raised to the 0 1 power is 1 2589
Thus it is seen that while the input has changed 4 decades
the output has only changed a little more than a factor of 2
It is also seen that with as little as 1 mV of offset the output
will also be greater than zero with zero input
25 mV at 10V input but the error is less than 10 mV for
l
k
1
1
m
e
R1
R2
a
R2
R1
a
th power of a number i e
R2
200
TL H 5695– 4
m
e
R1
R2
a
R2