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MAX8505EEE+

P1-P3P4-P6P7-P9P10-P12P13-P15
General Description
The MAX8505 step-down regulator operates from a 2.6V
to 5.5V input and generates an adjustable output voltage
from 0.8V to 0.85
VIN at up to 3A. With a 2.6V to 5.5V
bias supply, the input voltage can be as low as 2.25V.
The MAX8505 integrates power MOSFETs and
operates at 1MHz/500kHz switching frequency to
provide a compact design. Current-mode pulse-width-
modulated (PWM) control simplifies compensation with
ceramic or polymer output capacitors and provides
excellent transient response.
The MAX8505 features 1% accurate output over load,
line, and temperature variations. Adjustable soft-start is
achieved with an external capacitor. During the
soft-start period, the voltage-regulation loop is active.
This limits the voltage dip when the active devices,
such as microprocessors or ASICs connected to the
MAX8505’s output, apply a sudden load current step
upon passing their undervoltage thresholds.
The MAX8505 features current-limit, short-circuit, and
thermal-overload protection and enables a rugged
design. Open-drain power-OK (POK) monitors the
output voltage.
Applications
µP/ASIC/DSP/FPGA Core and I/O Supplies
Chipset Supplies
Server, RAID, and Storage Systems
Network and Telecom Equipment
Features
o Saves Space—4.9mm x 6mm Footprint, 1µH
Inductor, 47µF Ceramic Output Capacitor
o Input Voltage Range
2.6V to 5.5V
Down to 2.25V with Bias Supply
o 0.8V to 0.85
V
IN
, 3A Output
o Ceramic or Polymer Capacitors
o ±1% Output Accuracy Over Load, Line, and
Temperature
o Fast Transient Response
o Adjustable Soft-Start
o In-Regulation Soft-Start Limits Output-Voltage
Dips at Power-On
o POK Monitors Output Voltage
MAX8505
3A, 1MHz, 1% Accurate, Internal Switch
Step-Down Regulator with Power-OK
________________________________________________________________
Maxim Integrated Products
1
Ordering Information
19-2992; Rev 1; 9/10
PART TEMP RANGE PIN-PACKAGE
MAX8505EEE+ -40°C to +85°C 16 QSOP
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
LX
LX
PGND
LX
PGND
GND
REF
FB
COMP
TOP VIEW
MAX8505
QSOP
IN
LX
V
CC
IN
BST
POK
CTL
Pin Configuration
MAX8505
INPUT
2.6V TO 5.5V
ENABLE
POWER-OK
OUTPUT
0.8V TO
0.85 x V
IN
3A
BST
IN
V
CC
CTL
POK
GND
REF
COMP
FB
PGND
LX
Typical Operating Circuit
Functional Diagram appears at end of data sheet.
6
m
m
x
4
.
9
m
m
1
6
-
Q
S
O
P
EVALUATION KIT
AVAILABLE
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
+
Denotes a lead(Pb)-free/RoHS-compliant package.
MAX8505
3A, 1MHz, 1% Accurate, Internal Switch
Step-Down Regulator with Power-OK
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(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.)
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.
CTL, FB, IN, V
CC
to GND .........................................-0.3V to +6V
COMP, REF, POK to GND..........................-0.3V to (V
CC
+ 0.3V)
BST to LX..................................................................-0.3V to +6V
PGND to GND .......................................................-0.3V to +0.3V
Continuous Power Dissipation (T
A
= +70°C)
16-Pin QSOP (derate 12.5mW/°C above +70°C).......1000mW
Operating Temperature Range
MAX8505EEE...................................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Junction Temperature......................................................+150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
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 V
CC
2.6 5.5 V
V
IN
= 3.3V 6
10
IN Supply Current I
IN
Switching with no load
V
IN
= 5.5V 10
mA
V
CC
= 3.3V 3
10
V
CC
Supply Current I
CC
Switching with no load
V
CC
= 5.5V 6
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
20 50 µA
V
CC
rising 2.40 2.55
V
CC
Undervoltage Lockout
Threshold
UVLO
th
When LX starts/stops
switching
V
CC
falling 2.2 2.35
V
REF
REF Voltage V
REF
I
REF
= 0µA, V
IN
= V
CC
= 2.6V to 5.5V 0.792 0.800 0.808 V
REF Shutdown Resistance From REF to GND, V
CTL
= 0V 13 100 Ω
REF Soft-Start Current V
REF
= 0.4V 20 25 30 µA
Soft-Start Ramp Time
Output from 0% to 100%, C
REF
= 0.01µF to
1µF
32 ms/µF
FB
FB Regulation Voltage V
IN
= 2.6V to 5.5V 0.792 0.800 0.808 V
FB Input Bias Current V
FB
= 0.7V 0.01 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 12 13.5
FB Threshold for POK Transition FB rising or falling
FB low -13.5 -12 -10.5
%
FB to POK Delay FB rising or falling 50 µs
COMP
COMP Transconductance From FB to COMP 60 100 160 µS
Gain from FB to COMP V
COMP
= 1.25V to 1.75V 80 dB
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
P1-P3P4-P6P7-P9P10-P12P13-P15

MAX8505EEE+

Mfr. #:
Buy MAX8505EEE+
Manufacturer:
Maxim Integrated
Description:
Switching Voltage Regulators 3A 1MHz Step-Down Regulator
Lifecycle:
New from this manufacturer.
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