Datasheet

MAX8505
3A, 1MHz, 1% Accurate, Internal Switch
Step-Down Regulator with Power-OK
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= V
CC
= V
CTL
= +3.3V, V
FB
= 0.8V, V
COMP
= 1.25V, C
REF
= 0.01µF, T
A
= 0°C to +85°C, unless otherwise noted.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
COMP Clamp Voltage, Low V
IN
= V
CC
= 2.6V, 3.3V, 5.5V, V
FB
= 0.9V 0.45 0.75 1.00 V
COMP Clamp Voltage, High V
IN
= V
CC
= 2.6V, 3.3V, 5.5V, V
FB
= 0.7V 1.7 1.9 2.1 V
COMP Shutdown Resistance From COMP to GND, V
CTL
= 0V 13 100 Ω
LX (All LX Outputs Connected Together)
V
IN
= V
BST
- V
LX
= 3.3V
38 74
LX On-Resistance, High
V
IN
= V
BST
- V
LX
= 2.6V 42
mΩ
V
IN
= V
BST
- V
LX
= 3.3V
38 74
LX On-Resistance, Low
V
IN
= V
BST
- V
LX
= 2.6V 42
mΩ
LX C ur r ent- S ense Tr ansr esi stance R
T
From LX to COMP 0.068 0.086 0.104 Ω
Sourcing, Typical Application Circuit
4.6 5.6 6.6
LX Current-Limit Threshold
Sinking, V
IN
= V
CC
= 2.6V to 5.5V -4.3 -2.6 -1.0
A
V
LX
= 5.5V 100
LX Leakage Current
V
IN
= V
CC
= 5.5V,
V
CTL
= 0V
V
LX
= 0V -100
µA
V
CTL
= V
CC
0.85 1 1.15
LX Switching Frequency
V
IN
= V
CC
= 2.6V, 3.3V,
5.5V
V
CTL
= 2/3V
CC
0.44 0.5 0.56
MHz
LX Minimum Off-Time V
IN
= V
CC
= 2.6V, 3.3V, 5.5V 95 110 135 ns
500kHz 90 94
LX Maximum Duty Cycle
V
IN
= V
CC
= 2.6V, 3.3V,
5.5V
1MHz 84 89
%
500kHz 5 8
LX Minimum Duty Cycle
V
IN
= V
CC
= 2.6V, 3.3V,
5.5V
1MHz 10 15
%
SLOPE COMPENSATION
Slope Compensation Extrapolated to 100% duty cycle 245 300 400 mV
BST
V
LX
= 5.5V 10
V
LX
= 0V 10
BST Shutdown Supply Current
(V
BST
- V
LX
) = V
IN
=
V
CC
= 5.5V, V
CTL
= 0V
LX open 10
µA
CTL
For 1MHz 80
For 500kHz 55 70
CTL Input Threshold
V
IN
= V
CC
= 2.6V,
3.3V, 5.5V
For shutdown 45
% of
V
CC
CTL Input Current V
CTL
= 0V or 5.5V, V
IN
= V
CC
= 5.5V -1 +1 µA
POK (Power-OK)
POK Output Voltage, Low V
FB
= 0.6V or 1.0V, I
POK
= 2mA 25 100 mV
POK Leakage Current V
POK
= 5.5V 0.001 1 µA
POK Fault Delay Time From FB to POK, any threshold 25 50 100 µs
THERMAL SHUTDOWN
Thermal-Shutdown Threshold When LX stops switching T
J
rising +170 °C
Thermal-Shutdown Hysteresis 20 °C