MAX8505 Datasheet, PDF (1/15 Pages) Maxim Integrated Products – 3A, 1MHz, 1% Accurate, Internal Switch Step-Down Regulator with Power-OK

19-2992; Rev 0; 10/03
EVALUATION ^{KIT AVAILABLE}
16-QSOP 3A, 1MHz, 1% Accurate, Internal Switch
Step-Down Regulator with Power-OK
m _{x 4.9m}
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.
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
Ordering Information
Applications
µP/ASIC/DSP/FPGA Core and I/O Supplies
Chipset Supplies
Server, RAID, and Storage Systems
Network and Telecom Equipment
PART
MAX8505EEE
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
16 QSOP
Functional Diagram appears at end of data sheet.
TOP VIEW
LX ₁
IN 2
LX 3
IN 4
BST 5
V_CC 6
POK 7
CTL 8
Pin Configuration
MAX8505
QSOP
16 LX
15 PGND
14 LX
13 PGND
12 GND
11 REF
10 FB
9 COMP
Typical Operating Circuit
INPUT
2.6V TO 5.5V
ENABLE
POWER-OK
BST
IN
LX
MAX8505
PGND
V_CC
FB
COMP
CTL
REF
POK
GND
OUTPUT
0.8V TO
0.85 x V_IN
3A
________________________________________________________________ Maxim Integrated Products 1
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