LT1632CS8 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
LT1632CS8
Linear Technology
'LT1632CS8' PDF : 16 Pages View PDF
LT1632/LT1633
APPLICATIONS INFORMATION
V+
R6
+ IN 225Ω
D6 D8
R7
D5 D7
– IN 225Ω
D1
D2
Q4 Q3
Q7
V–
+
I1
Q5
VBIAS
Q1 Q2
D3
D4
Q6
R3
R4
R5
Q12
Q11
Q13
+
I2
V–
CC
Q15
C2
OUT
Q9
Q8
R1
R2
BUFFER
AND
OUTPUT BIAS
C1
Q14
1632/33 F01
Figure 1. LT1632 Simplified Schematic Diagram
amplifiers operate over a very wide supply range, it is
possible to exceed the maximum junction temperature of
150°C in plastic packages under certain conditions. Junc-
tion temperature TJ is calculated from the ambient tem-
perature TA and power dissipation PD as follows:
LT1632CN8: TJ = TA + (PD • 130°C/W)
LT1632CS8: TJ = TA + (PD • 190°C/W)
LT1633CS: TJ = TA + (PD • 150°C/W)
The power dissipation in the IC is the function of the supply
voltage, output voltage and load resistance. For a given
supply voltage, the worst-case power dissipation PDMAX
occurs at the maximum supply current and when the
output voltage is at half of either supply voltage (or the
maximum swing if less than 1/2 supply voltage). There-
fore PDMAX is given by:
PDMAX = (VS • ISMAX) + (VS/2)2/RL
To ensure that the LT1632/LT1633 are used properly,
calculate the worst-case power dissipation, use the ther-
mal resistance for a chosen package and its maximum
junction temperature to derive the maximum ambient
temperature.
Example: An LT1632CS8 operating on ±15V supplies and
driving a 500Ω, the worst-case power dissipation per
amplifier is given by:
PDMAX = (30V • 5.6mA) + (15V – 7.5V)(7.5/500)
= 0.168 + 0.113 = 0.281W
If both amplifiers are loaded simultaneously, then the total
power dissipation is 0.562W. The SO-8 package has a
junction-to-ambient thermal resistance of 190°C/W in still
air. Therefore, the maximum ambient temperature that the
part is allowed to operate is:
TA = TJ – (PDMAX • 190°C/W)
TA = 150°C – (0.562W • 190°C/W) = 43°C
For a higher operating temperature, lower the supply
voltage or use the DIP package part.
Input Offset Voltage
The offset voltage changes depending upon which input
stage is active, and the maximum offset voltages are
trimmed to less than 1350µV. To maintain the precision
characteristics of the amplifier, the change of VOS over the
entire input common mode range (CMRR) is guaranteed
to be less than 1500µV on a single 5V supply.
Input Bias Current
The input bias current polarity depends on the input
common mode voltage. When the PNP differential pair is
active, the input bias currents flow out of the input pins.
12
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