ltc6652ahms8-5-trpbf Linear Technology Corporation, ltc6652ahms8-5-trpbf Datasheet - Page 9

• Manufacturer Part Number: ltc6652ahms8-5-trpbf
• Description: Precision Low Drift Low Noise Buffered Reference
• Manufacturer: Linear Technology Corporation

APPLICATIONS INFORMATION
Hysteresis
The hysteresis data shown in Figure 13 represents the
worst-case data collected on parts from –40°C to 125°C.
The output is capable of dissipating relatively high power,
i.e., for the LT6652-2.5, P
The thermal resistance of the MS8 package is 200°C/W and
this dissipation causes a 11.8°C internal rise. This could
increase the junction temperature above 125°C and may
cause the output to shift due to thermal hysteresis.
PC Board Layout
The mechanical stress of soldering a surface mount volt-
age reference to a PC board can cause the output voltage
to shift and temperature coeffi cient to change. These two
changes are not correlated. For example, the voltage may
shift, but the temperature coeffi cient may not.
To reduce the effects of stress-related shifts, mount the
reference near the short edge of the PC board or in a
corner. In addition, slots can be cut into the board on two
sides of the device.
100
–20
–40
80
60
40
20
0
0
LTC6652-2.5 MS8 PACKAGE
3 TYPICAL PARTS
T
A
= 33°C
Figure 12. Long Term Drift
200
400
D
HOURS
= 10.7V • 5.5mA = 58.85mW.
600
800
6652 F12
1000
The capacitors should be mounted close to the package.
The GND and V
to minimize I • R drops. Excessive trace resistance directly
impacts load regulation.
Power Dissipation
Power dissipation in the LTC6652 is dependent on V
load current, and package. The LTC6652 package has
a thermal resistance, or θ
illustrates allowed power dissipation vs temperature for
this package is shown in Figure 14.
The power dissipation of the LTC6652-2.5V as a function
of input voltage is shown in Figure 15. The top curve
shows power dissipation with a 5mA load and the bottom
curve shows power dissipation with no load.
When operated within its specifi ed limits of V
and sourcing 5mA, the LTC6652-2.5 consumes just under
60mW at room temperature. At 125°C the quiescent cur-
rent will be slightly higher and the power consumption
increases to just over 60mW. The power-derating curve
in Figure 14 shows the LTC6652-2.5 can safely dissipate
125mW at 125°C about half the maximum power con-
sumption of the package.
Figure 13. Hysteresis Plot –40°C to 125°C
35
30
25
20
15
10
5
0
–250
OUT
125°C TO 25°C
traces should be as short as possible
–150
DISTRIBUTION (ppm)
JA
–50
, of 200°C/W. A curve that
50
–40°C TO 25°C
LTC6652
150
6652 F13
IN
= 13.2V
9
6652f
IN
,