MAX887
100% Duty Cycle, Low-Noise,
Step-Down, PWM DC-DC Converter
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V+ = +7V, PGND = GND = 0V, SHDN = V+, (T
A
= 0°C to T
MAX
), unless otherwise noted.)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
REF, FB, SYNC, VL to GND..................................... -0.3V to +6V
V+ to GND............................................................. -0.3V to +12V
SHDN, LX to GND ....................................... -0.3V to (V+ + 0.3V)
PGND to GND ...................................................... -0.3V to +0.3V
Continuous Power Dissipation (T
A
= +70°C)
SO (derate 9.09mW/°C above +70°C) .........................471mW
Operating Temperature Ranges
MAX887HC/D.......................................................0°C to +70°C
MAX887HESA...................................................-40°C to +85°C
Storage Temperature Range ........................... -65°C to +165°C
Lead Temperature (soldering, 10sec)............................ +300°C
SYNC = GND or 3V
I
OUT
= 0mA, SYNC = GND
V+ rising
I
OUT
= 0mA, SYNC = 3.0V
V+ falling
V+ = floating, LX = 5V, SHDN = GND
V+ = 12V, LX = GND to 12V
I
LX
= ±100mA
SYNC = 3.0V
FB = 1.30V
SYNC = 3.0V, PWM duty cycle = 50%
SHDN = GND
Circuit of Figure 2
I
OUT
= 0mA to 500mA
V
IN
= 4V to 11V, PWM mode
SYNC = 3.0V, FB = 1.18V
CONDITIONS
V2.4V
IH, SHDN
SHDN Input High Voltage
µA±1I
IN, SYNC
SYNC Input Current
V0.5V
IL, SYNC
SYNC Input Low Voltage
V2.5V
IH, SYNC
SYNC Input High Voltage
V3.1 3.5V
+, START
Startup Voltage
V3.0 3.3V
+, UVLO
Undervoltage Lockout
µA1.0 20I
LXLKGR
LX Reverse Leakage Current,
Regulator Off
µA-10 1.0 10I
LXLKG
LX Leakage Current
Ω0.6R
ON, LX
LX On-Resistance
A0.75 1.0 1.40I
LIM+
High-Side Current Limit
kHz260 300 340f
OSC
PWM Switching Frequency
SHDN Input Low Voltage
V
IL, SHDN
%100PWM, DUTYPWM Maximum Duty Cycle
mA0.2 0.5I
V+, PFM
Quiescent Supply Current
(PFM Mode)
mA2.7 4.0I
V+, PWM
V3.5 11.0V+Supply Range
Quiescent Supply Current
(PWM Mode)
ns500SYNC, PWSYNC Pulse Width High or Low
kHz25 440f
SYNC
SYNC Frequency
µA±0.10I
FB
FB Input Current
V1.225 1.250 1.275V
FB
PWM FB Feedback Threshold
µA2.5 5I
V+, SHDN
Shutdown Supply Current
V1.25 10.50V
OUT, RANGE
Output Voltage Range
%/mA0.005Load Regulation
%/V0.2Line Regulation
UNITSMIN TYP MAXSYMBOLPARAMETER
0.8 V
SHDN Input Current, Sinking
I
IN-, SHDN
SHDN = GND or V+
±1 µA
SHDN Input Capacitance
C
IN, SHDN
(Note 1) 10 pF
VL Output Voltage V
L
I
VL
= 0mA to 1mA 3.3 V
REF Output Voltage V
REF
0µA to 30µA 1.25 V
Note 1: Guaranteed by design and not production tested.
(16 Seiten)
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