Datasheet

MAX887
100% Duty Cycle, Low-Noise,
Step-Down, PWM DC-DC Converter
_______________________________________________________________________________________ 3
Note 2: Specifications from 0°C to -40°C are guaranteed by design and not production tested.
I
OUT
= 0mA, SYNC = GND
V+ rising
I
OUT
= 0mA, SYNC = 3.0V
V+ falling
SYNC = 3.0V
FB = 1.30V
SYNC = 3.0V, PWM duty cycle = 50%
SHDN = GND
Circuit of Figure 2
CONDITIONS
V3.1 3.5V
+, START
Startup Voltage
V3.0 3.3V
+, UVLO
Undervoltage Lockout
A0.75 1.00 1.50I
LIM+
High-Side Current Limit
kHz250 300 350f
OSC
PWM Switching Frequency
mA0.2 0.6I
V+, PFM
Quiescent Supply Current
(PFM Mode)
mA2.7 4.0I
V+, PWM
V3.5 11.0V+Supply Range
Quiescent Supply Current
(PWM Mode)
µA±0.10I
FB
FB Input Current
V1.222 1.250 1.278V
FB
PWM FB Feedback Threshold
µA2.5 5I
V+, SHDN
Shutdown Supply Current
V1.25 10.50V
OUT, RANGE
Output Voltage Range
UNITSMIN TYP MAXSYMBOLPARAMETER
ELECTRICAL CHARACTERISTICS
(V+ = +7V, PGND = GND = 0V, SHDN = V+, (T
A
= -40°C to +85°C), unless otherwise noted.) (Note 2)
__________________________________________Typical Operating Characteristics
(Circuit of Figure 2, T
A
= +25°C, unless otherwise noted.)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 200 400 600 800 1000
LOAD CURRENT (mA)
DROPOUT VOLTAGE
vs. LOAD CURRENT
MAX887-01
DROPOUT VOLTAGE (V)
3.3V SETTING
V
OUT
= 3.135V
5V SETTING
V
OUT
= 4.75V
0
10
20
30
40
50
60
70
80
90
100
0.0001 0.001 0.01 0.1 0.6
EFFICIENCY (%)
OUTPUT CURRENT (A)

EFFICIENCY vs. OUTPUT CURRENT
MAX887-02
PWM MODE
(SYNC = VL)
V
OUT
= 3.3V
V
IN
= 4V

V
IN
= 5V
V
IN
= 7V

V
IN
= 11V
V
IN
= 9V
0
10
20
30
40
50
60
70
80
90
100
0.0001 0.001 0.01 0.1 0.6
EFFICIENCY (%)
OUTPUT CURRENT (A)

EFFICIENCY vs. OUTPUT CURRENT
MAX887-03
PWM MODE
(SYNC = VL)
V
OUT
= 5V
V
IN
= 9V

V
IN
= 5.5V
V
IN
= 11V
V
IN
= 7V
