LT6654 Linear Technology, LT6654 Datasheet - Page 9

• Manufacturer Part Number: LT6654
• Description: SOT-23 Precision Wide Supply High Output Drive Voltage Reference
• Manufacturer: Linear Technology

APPLICATIONS INFORMATION
to three times through this refl ow process show that the
standard deviation of the output voltage increases with a
slight negative mean shift of 0.003% as shown in Figure 9.
While there can be up to 0.014% of output voltage shift,
the overall drift of the LT6654 after IR refl ow does not
vary signifi cantly.
Power Dissipation
The power dissipation in the LT6654 is dependent on V
load current and the package. The LT6654 package has
a thermal resistance, or θ
illustrates allowed power dissipation versus temperature
for the 6-lead SOT-23 package is shown in Figure 10.
The power dissipation of the LT6654-2.5 as a function of
input voltage is shown in Figure 11. The top curve shows
Figure 9. Output Voltage Shift Due to IR Refl ow (%)
14
12
10
8
6
2
0
4
–140
260°C 3 CYCLES
260°C 1 CYCLE
–120 –100 –80 –60
CHANGE IN OUTPUT (ppm)
JA
, of 230°C/W. A curve that
–40
Figure 11. Typical Power Dissipation of the LT6654
–20
6654 F09
0
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0
0
5
10
IN
10mA LOAD
15
,
V
IN
20
(V)
power dissipation with a 10mA load and the bottom curve
shows power dissipation with no load. When operated
within its specifi ed limits of V
10mA, the LT6654-2.5 consumes about 335mW at room
temperature. The power-derating curve in Figure 10
shows the LT6654-2.5 can only safely dissipate 108mW
at 125°C, which is less than its maximum power output.
Care must be taken when designing the circuit so that the
maximum junction temperature is not exceeded.
The LT6654 includes output current limit circuitry, as well
as thermal limit circuitry, to protect the reference from
damage in the event of excessive power dissipation. The
LT6654 is protected from damage by a thermal shutdown
circuit. However, changes in performance may occur as
a result of operation at high temperature.
NO LOAD
25
Figure 10. Maximum Allowed Dissipation for LT6654
30
335mW
35
6654 F11
0.6
0.5
0.4
0.3
0.1
0.7
0.2
0
40
0
20
40
TEMPERATURE (°C)
60
80
IN
θ
100
JA
= 36V and sourcing
= 230°C/W
T = 150°C
120
108mW
6654 F10
140
LT6654
9
6654f