LT6656 Linear Technology Corporation, LT6656 Datasheet - Page 10

• Manufacturer Part Number: LT6656
• Description: 1?a Precision Series Voltage Reference
• Manufacturer: Linear Technology Corporation

LT6656
applicaTions inForMaTion
Regulator Reference
The robust input and output of the LT6656 along with its
high output current make it an excellent precision low
power regulator as well as a reference. The LT6656 would
Typical applicaTions
0
Figure 10. Lead Free Reflow Profile Due to IR Reflow
Figure 11. Output Voltage Shift Due to IR Reflow,
Peak Temperature = 260°C
300
225
150
75
0
7
6
5
4
3
2
1
0
0
RAMP TO
150°C
T = 150°C
V
C
I
0
L
T
IN
L
= 0
S
= 1µF
20
= 3V
CHANGE IN OUTPUT VOLTAGE (ppm)
= 190°C
T
2
S(MAX)
60
= 200°C
4
380s
MINUTES
T
120s
L
100
= 217°C
3V TO 18V
T
P
6
= 260°C
140
130s
40s
30s
t
t
P
L
0.1µF
8
180
C13
3 CYCLES
1 CYCLE
DOWN
RAMP
6656 F10
6656 F11
220
10
Microcontroller Reference and Regulator
IN
LT6656
OUT
run through the reflow process for 1 cycle and also 3
cycles. The results indicate that the standard deviation
of the output voltage increases with a positive mean shift
of 120ppm. While there can be up to 220ppm of output
voltage shift, additional drift of the LT6656 after IR reflow
does not vary significantly.
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 coefficient to change.
To reduce the effects of stress-related shifts, position
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. See Application Note AN82 for more
information. http://www.linear.com
The input and output capacitors should be mounted close
to the package. The GND and V
short as possible to minimize the voltage drops caused
by load and ground currents. Excessive trace resistance
directly impacts load regulation.
be a good match with a small, low power microcontroller.
Using the LT6656 as a regulator reduces power consump-
tion, decreases solution size and increases the accuracy
of the microcontroller’s on board ADC.
C12
10µF
MCU
PB1/INT0/A
PB2/ADC1/SCK/T0/INT0
PB0/AIN0/A
V
CC
GND
PB5/RESET/ADC0
/V
IN1
REF
/MISO/OC1A
PB3/ADC2
PB4/ADC3
REF
/MOSI
6656 TA02
5
6
7
2
3
1
OUT
traces should be as
6656f