MAX8505 MAXIM [Maxim Integrated Products], MAX8505 Datasheet - Page 5

• Manufacturer Part Number: MAX8505
• Description: 3A, 1MHz, 1% Accurate, Internal Switch Step-Down Regulator with Power-OK
• Manufacturer: MAXIM [Maxim Integrated Products]

ELECTRICAL CHARACTERISTICS (continued)
(V
Note 1: Under normal operating conditions, COMP moves between 1.25V and 2.15V as the duty cycle changes from 10% to 90%
Note 2: Specifications to -40°C are guaranteed by design and not production tested.
Note 3: LX has internal clamp diodes to PGND and IN pins 2 and 4. Applications that forward bias these diodes should take care
Note 4: When connected together, the LX output is designed to provide 3.5A
LX Maximum Duty Cycle
LX Minimum Duty Cycle
SLOPE COMPENSATION
Slope Compensation
BST
BST Shutdown Supply Current
CTL
CTL Input Threshold
CTL Input Current
POK (Power-OK)
POK Output Voltage, Low
POK Leakage Current
POK Fault Delay Time
IN
= V
CC
and peak inductor current changes from 0 to 3A. Maximum output current is related to peak inductor current, inductor value
input voltage, and output voltage by the following equations:
where V
on-resistance of low-side switch; L = inductor. Equations for I
where I
±20%); D = duty cycle:
where V
side switch; R
not to exceed the IC’s package power dissipation limits.
PARAMETER
= V
CTL
LIM_DC100
OUT
OUT
= +3.3V, V
_______________________________________________________________________________________
= output voltage; I
= output voltage; V
3A, 1MHz, 1% Accurate, Internal Switch
NLS
= current limit at D = 100%; R
= on-resistance of low-side switch. See the Typical Application Circuit for external components.
FB
Step-Down Regulator with Power-OK
= 0.8V, V
SYMBOL
LIM
IN
COMP
I
OUT MAX
= input voltage; I
= current limit of high-side switch; t
_
= 1.25V, C
V
5.5V
V
5.5V
Extrapolated to 100% duty cycle
(V
V
V
3.3V, 5.5V
V
V
V
From FB to POK, any threshold
IN
IN
CC
IN
CTL
FB
POK
BST
=
I
LIM
= V
D
= V
= V
= 0.6V or 1.0V, I
= 5.5V, V
1 1
= 0V or 5.5V, V
=
= 5.5V
I
+ −
- V
LIM
T
=
CC
CC
CC
(
V
V
I
IN
= transresistance from LX to COMP; V
LX
LIM DC
OUT
REF
− −
O
= 2.6V, 3.3V,
= 2.6V, 3.3V,
= 2.6V,
D
) = V
+
(
1
)
_
I R
= output current; R
O
×
= 0.01µF, T
+
CTL
(
t
D
I R
CONDITIONS
S
O
IN
100
)
NLS
×
(
×
= 0
=
(
t
NLS
R
S
+
LIM
IN
POK
NLS
−
×
V
R
SW
V
= V
+
NHS
and D are shown as follows:
OUT
R
+
= 2mA
A
1
L
R
CC
R
= -40°C to +85°C, unless otherwise noted.) (Note 2)
500kHz
1MHz
500kHz
1MHz
V
V
LX open
For 1MHz
For 500kHz
For shutdown
−
)
L
)
RMS
T
/
LX
LX
D
) /
S
2
= 5.5V
L
2
= switching period; R
L
= 5.5V
= 0V
L
current.
= ESR of inductor; R
SW
MIN
245
90
84
80
55
25
-1
= slope compensation (310mV
L
NHS
= ESR of inductor; R
TYP
= on-resistance of high-
MAX
406
100
100
+1
15
10
10
10
70
45
8
1
NLS
UNITS
% of
V
mV
mV
µA
µA
µA
µs
%
%
CC
=
5