LT1790BIS6-2.048#PBF Linear Technology, LT1790BIS6-2.048#PBF Datasheet - Page 21

• Manufacturer Part Number: LT1790BIS6-2.048#PBF
• Manufacturer: Linear Technology

Specifications of LT1790BIS6-2.048#PBF

• Fixed / Adjust / Prog: Precision
• Output Voltage (max): 2.048V
• Temperature Coefficient: 25ppm/°C
• Reference Voltage Accuracy (max): 0.1
• Line Regulation: 170ppm/V
• Load Regulation: 260ppm/mA
• Input Voltage (max): 20V
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 6
• Package Type: TSOT-23
• Lead Free Status / RoHS Status: Compliant

APPLICATIONS INFORMATION
Hysteresis
Hysteresis data shown in Figures 8 and 9 represent the
worst-case data taken on parts from 0°C to 70°C and from
– 40°C to 85°C. Units were cycled several times over these
temperature ranges and the largest change is shown. As
expected, the parts cycled over the higher temperature
range have higher hysteresis than those cycled over the
lower range.
In addition to thermal hysteresis, the thermal shock as-
sociated with high temperature soldering may cause the
output to shift. For traditional PbSn solder temperatures,
the output shift of the LT1790 is typically just 150ppm
(0.015%).
Figure 9. Worst-Case –40°C to 85°C Hysteresis on 80 Units
25
Figure 8. Worst-Case 0°C to 70°C Hysteresis on 79 Units
35
30
20
15
10
50
45
40
30
25
20
15
10
0
5
0
5
–100
–60 –50 –40 –30 –20 –10
70°C TO 25°C
–80 –60
80°C TO 25°C
–40
DISTRIBUTION (ppm)
DISTRIBUTION (ppm)
–20
0
0
10
20
20
40
30 40
0°C TO 25°C
–40°C TO 25°C
60
80
50
1790 F09
1790 F08
100
60
For lead-free solder, IR reflow temperatures are much
higher, often 240°C to 260°C at the peak. As a result, the
packaging materials have been optimized to reduce V
shift as possible during high temperature reflow. In addi-
tion, care should be taken when using lead-free solder to
minimize the peak temperature and dwell time as much
as is practical. A typical lead-free reflow profile is shown
in Figure 10. LT1790 units were heated using a similar
profile, with a peak temperature of 250°C. These parts
were run through the heating process 3 times to show the
cumulative effect of these heat cycles. Figure 11 shows
Figure 11. 1X IR Refl ow Peak Temperature = 250°C,
7
6
4
3
2
1
0
9
8
5
225
150
300
75
0
Figure 10. Lead-Free Refl ow Profi le
0
0
RAMP TO
150°C
T = 150°C
Delta Output Voltage (ppm)
T = 190°C
10
2
T
S(MAX)
20
380s
= 200°C
4
MINUTES
120s
T
PPM
L
= 217°C
T
P
30
6
= 260°
130s
130s
40s
t
t
L
P
8
40
RAMP
DOWN
1790 F10
LT1790
10
50
1790 F11
21
1790fb
OUT