MAX866 Maxim, MAX866 Datasheet - Page 8

• Manufacturer Part Number: MAX866
• Description: 3.3V/5V or Adjustable-Output / Single-Cell DC-DC Converters
• Manufacturer: Maxim

The precision voltage reference is suitable for driving
external loads, such as an analog-to-digital converter.
The voltage-reference output changes less than ±2%
when sourcing up to 250µA and sinking up to 20µA. If
the reference drives an external load, bypass it with
0.22µF to GND. If the reference is unloaded, bypass it
with at least 0.1µF.
The 3/5 input is internally diode clamped to GND and
OUT, and should not be connected to signals outside
this range. The SHDN input and LBO output (open-
drain) are not clamped to V+ and can be pulled as high
as 7V regardless of the voltage at OUT
control inputs (3/5, LBI, or SHDN) floating.
3.3V/5V or Adjustable-Output,
Single-Cell DC-DC Converters
Figure 2a. Standard Application Circuit—Preset Output
Voltage
8
0.1 F
C3
_______________________________________________________________________________________
L1 = COILCRAFT DO1608-334
D1 = MOTOROLA MBR0520LTI
V
IN
5
1
3
LBI
SHDN
REF
MAX866
7
GND
Logic Inputs and Outputs
C1
47 F
OUT
LBO
3/5
LX
Voltage Reference
8
6
2
4
L1
330 H
OUTPUT
SELECT
D1
R1
.
Do not leave
C2
47 F
V
OUT
For the MAX866, you can select a 3.3V or 5V output volt-
age under logic control, or by tying 3/5 to GND or OUT.
The MAX867’s output voltage is set by two resistors, R1
and R2 (Figure 2b), which form a voltage divider
between the output and FB. Use the following equation
to determine the output voltage:
where V
To simplify resistor selection:
Figure 2b. Standard Application Circuit—Adjustable Output
Voltage
__________________Design Procedure
0.1 F
C3
L1 = COILCRAFT DO1608-334
D1 = MOTOROLA MBR0520LTI
REF
V
R1 = R2
OUT
= 1.25V.
5
1
3
V
IN
LBI
SHDN
REF
= V
(
REF
MAX867
_____ - 1
V
V
7
OUT
REF
GND
Output Voltage Selection
(
________
R1 + R2
C1
47 F
OUT
LBO
R2
)
LX
FB
8
6
2
4
)
L1
330 F
D1
R1
R2
C2
47 F
V
OUT