Datasheet
MAX856–MAX859
3.3V/5V or Adjustable-Output,
Step-Up DC-DC Converters
_______________________________________________________________________________________ 3
100
20
10
0
0.010.001
0.1
10
1
100 1000
MAX858/MAX859
EFFICIENCY vs. OUTPUT CURRENT
V
OUT
= 3.3V
40
30
50
MAX856-01
LOAD CURRENT (mA)
EFFICIENCY (%)
60
70
80
90
V
IN
= 2.0V
V
IN
= 2.5V
V
IN
= 1.5V
100
20
10
0
0.010.001
0.1
10
1
100 1000
MAX858/MAX859
EFFICIENCY vs. OUTPUT CURRENT
V
OUT
= 5V
40
30
50
MAX856-02
LOAD CURRENT (mA)
EFFICIENCY (%)
60
70
80
90
V
IN
= 2.5V
V
IN
= 3.3V
V
IN
= 1.5V
100
20
10
0
0.010.001
0.1
10
1
100 1000
MAX856/MAX857
EFFICIENCY vs. OUTPUT CURRENT
V
OUT
= 5V
40
30
50
MAX856-03
LOAD CURRENT (mA)
EFFICIENCY (%)
60
70
80
90
V
IN
= 2.0V
V
IN
= 3.3V
V
IN
= 1.5V
100
20
10
0
0.010.001
0.1
10
1
100 1000
MAX856/MAX857
EFFICIENCY vs. OUTPUT CURRENT
V
OUT
= 3.3V
40
30
50
MAX856-04
LOAD CURRENT (mA)
EFFICIENCY (%)
60
70
80
90
V
IN
= 2.0V
V
IN
= 2.5V
V
IN
= 1.5V
__________________________________________Typical Operating Characteristics
(Circuits of Figure 2, T
A
= +25°C, unless otherwise noted.)
ELECTRICAL CHARACTERISTICS (continued)
(Circuits of Figure 2, V
IN
= 2.5V, I
LOAD
= 0mA, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
Note 2: Supply current from the 3.3V output is measured with an ammeter between the 3.3V output and OUT pin. This current
correlates directly with actual battery supply current, but is reduced in value according to the step-up ratio and efficiency.
V
OUT
= 3.47V to keep the internal switch open when measuring the current into the device.
Note 3: Minimum value is production tested. Maximum value is guaranteed by design and is not production tested.
–
S
—
H
—
D
—
N
–
, 3/
–
5
–
Input Voltage Low
0.4 V
S
—
H
—
D
—
N
–
, 3/
–
5
–
Input Voltage High 1.6 V
S
—
H
—
D
—
N
–
, 3/
–
5
–
, FB, LBI Input Current LBI = 1.5V, FB = 1.5V,
–
S
—
H
—
D
—
N
–
= 0V or 3V, 3/
–
5
–
= 0V or 3V ±100 nA
FB Voltage MAX857/MAX859 1.22 1.25 1.28 V
Output Voltage Range MAX857/MAX859, I
LOAD
= 0mA (Note 3) 2.7 6.0 V