Datasheet

MAX1927/MAX1928
Low-Output-Voltage, 800mA, PWM Step-Down
DC-DC Converters
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(V
BATT
= 3.6V, SHDN = BATT, C
REF
= 0.1µF, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER CONDITIONS
MIN MAX
UNITS
FB Input Current MAX1927R 150 nA
Reference Voltage Accuracy
1.22 1.269
V
Reference-Supply Rejection 2.6V < V
BATT
< 5.5V 2 mV
PWM CONTROLLER
V
BATT
= 3.6V 0.4
P-Channel On-Resistance
V
BATT
= 2.6V 0.5
Ω
V
BATT
= 3.6V
0.30
N-Channel On-Resistance
V
BATT
= 2.6V
0.35
Ω
P-Channel Current-Limit Threshold 1.1
0.10
1.6 A
P-Channel Pulse-Skipping Current Threshold
0.10 0.16
A
LX Leakage Current V
BATT
= 5.5V, LX = GND or BATT -20
+20
µA
Maximum Duty Cycle
100
%
Minimum Duty Cycle PWM = GND 0 %
Internal Oscillator Frequency 0.8 1.2
MHz
POK COMPARATOR
BATT Operating Voltage Range I
POK
= 0.1 mA 1 5.5 V
Output Low Voltage V
FB
= 0.5V, I
POK
= 1mA 0.1 V
Output High Leakage Current V
POK
= 5.5V 1 µA
MAX1927R
0.650 0.700
MAX1928-15
1.305 1.395
MAX1928-18
1.566 1.674
POK Threshold
MAX1928-25
2.175 2.325
V
Output Valid to POK Release Delay
POK transitions to high impedance 20ms
after V
FB
> V
POK
15 25 ms
LOGIC INPUTS (SHDN, PWM)
Logic Input High 2.6V < V
BATT
< 5.5 V 1.6 V
Logic Input Low 2.6V < V
BATT
< 5.5 V 0.6 V
Logic Input Current V
BATT
= 5.5V 1 µA