Datasheet
MAX8505
3A, 1MHz, 1% Accurate, Internal Switch
Step-Down Regulator with Power-OK
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS
(V
IN
= V
CC
= V
CTL
= +3.3V, V
FB
= 0.8V, V
COMP
= 1.25V, C
REF
= 0.01µF, T
A
= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
IN AND V
CC
IN Voltage Range V
IN
2.25 V
CC
V
V
CC
Voltage Range 2.6 5.5 V
IN Supply Current I
IN
Switching with no load V
IN
= 3.3V
10 mA
V
CC
Supply Current I
CC
Switching with no load V
CC
= 3.3V
10 mA
Total Shutdown Current into IN
and V
CC
I
SHDN
V
IN
= V
CC
= V
BST
- V
LX
= 5.5V, V
CTL
= 0V,
V
LX
= 0V
50 µA
V
CC
rising 2.55
V
CC
Undervoltage Lockout
Threshold
UVLO
th
When LX starts/stops
switching
V
CC
falling 2.2
V
REF
REF Voltage V
REF
I
REF
= 0µA, V
IN
= V
CC
= 2.6V to 5.5V 0.791 0.808 V
REF Shutdown Resistance From REF to GND, V
CTL
= 0V 100 Ω
REF Soft-Start Current V
REF
= 0.4V 20 30 µA
FB
FB Regulation Voltage V
FB
V
IN
= 2.6V to 5.5V 0.791 0.808 V
FB Input Bias Current V
FB
= 0.7V 0.1 µA
Maximum Output Current I
OUT_MAX
V
IN
= V
CC
= 3.3V, V
OUT
= 1.2V,
L = 1µH/5.9mΩ (Note 1)
3A
FB high 10.5 13.5
FB Threshold for POK Transition FB rising or falling
FB low -13.5 -10.5
%
COMP
COMP Transconductance From FB to COMP 60 160 µS
COMP Clamp Voltage, Low V
IN
= V
CC
= 2.6V, 3.3V, 5.5V, V
FB
= 0.9V 0.45 1.00 V
COMP Clamp Voltage, High V
IN
= V
CC
= 2.6V, 3.3V, 5.5V, V
FB
= 0.7V 1.7 2.1 V
COMP Shutdown Resistance From COMP to GND, V
CTL
= 0V 100 Ω
LX (All LX Outputs Connected Together)
LX On-Resistance, High
V
IN
= V
BST
- V
LX
= 3.3V
74 mΩ
LX On-Resistance, Low
V
IN
= V
BST
- V
LX
= 3.3V
74 mΩ
LX C ur r ent- S ense Tr ansr esi stance R
T
From LX to COMP 0.068 0.104 Ω
Sourcing, Typical Application Circuit
4.6 5.6
LX Current-Limit Threshold
Sinking, V
IN
= V
CC
= 2.6V to 5.5V -4.3 -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
1.15
LX Switching Frequency
V
IN
= V
CC
= 2.6V,
3.3V, 5.5V
V
C TL
= 2/3 ✕ V
C C
0.44
0.56
MHz
LX Minimum Off-Time V
IN
= V
CC
= 2.6V, 3.3V, 5.5V 95 135 ns