MAX1536 Datasheet, PDF (1/19 Pages) Maxim Integrated Products – 3.6A, 1.4MHz, Low-Voltage, Internal-Switch Step-Down Regulator with Dynamic Output Voltage Control

LCJ/JH 9/22/05 (P1)
19-2729; Rev 1; 8/05
EVAALVUAAILTAIOBNLEKIT
3.6A, 1.4MHz, Low-Voltage, Internal-Switch Step-
Down Regulator with Dynamic Output Voltage Control
General Description
The MAX1536 constant-off-time, pulse-width-modulated
(PWM) step-down DC-to-DC converter is ideal for use in
+5.0V and +3.3V to low voltages for notebook and sub-
notebook computers. The MAX1536 features an internal
PMOS power switch and internal synchronous rectifica-
tion for high efficiency and reduced component count. No
external Schottky diode is required across the internal
synchronous rectifier switch. The internal 54mΩ PMOS
power switch and 47mΩ NMOS synchronous-rectifier
switch easily deliver continuous load currents up to 3.6A.
The MAX1536 produces dynamically adjustable output
voltages for chipsets and graphics processor cores using
a logic-level control signal. The MAX1536 achieves effi-
ciencies as high as 96%.
The MAX1536 uses a unique current-mode, constant-off-
time, PWM control scheme. It has selectable Idle
Mode^TM to maintain high efficiency during light-load
operation, or fixed-PWM mode for low output ripple. The
programmable constant-off-time architecture allows a
wide range of switching frequencies up to 1.4MHz, opti-
mizing performance trade-offs between efficiency, output
switching noise, component size, and cost. The
MAX1536 features a digital soft-start to limit surge cur-
rents during startup, a 100% duty-cycle mode for low-
dropout operation, and a low-power shutdown mode that
disconnects the input from the output and reduces supply
current below 1µA. The MAX1536 is available in a 28-pin
thin QFN package with an exposed backside pad.
________________________Applications
Chipset/Graphics Cores
with Dual-Supply Voltages
Active Termination Buses
Notebook Computers
DDR Memory Termination
Pin Configuration
Features
♦ Dynamically Selectable Output Voltage from
+0.7V to V_IN
♦ Internal PMOS/NMOS Switches
54mΩ/47mΩ On-Resistance at V_IN = +4.5V
63mΩ/53mΩ On-Resistance at V_IN = +3.0V
♦ +3.0V to +5.5V Input Voltage Range
♦ 1.4MHz Maximum Switching Frequency
♦ 2V ±0.75% Reference Output
♦ Constant-Off-Time PWM Operation
♦ Selectable Idle Mode/PWM Operation at Light
Loads
♦ 100% Duty Factor in Dropout
♦ Digital Soft-Start Inrush Current Limiting
♦ <1µA Typical Shutdown Supply Current
♦ <750µA Quiescent Supply Current
♦ Thermal Shutdown
♦ 1% V_OUT Accuracy Over Line and Load
♦ External Reference Input
♦ Power-Good Window Comparator
♦ Selectable Power-Good Blanking Time During
Output-Voltage Transition
Ordering Information
PART
MAX1536ETI
MAX1536ETI+
TEMP RANGE
-40^oC to +85^oC
-40^oC to +85^oC
PIN-PACKAGE
28 Thin QFN 5mm x 5mm
28 Thin QFN 5mm x 5mm
+Denotes lead-free package.
Minimal Operating Circuit
TOP VIEW
21 20 19 18 17 16 15
PGND 22
14 REF
PGND 23
13 REFIN
LX 24
12 OD
N.C. 25
LX 26
MAX1536
11 OD
10 GATE
PGND 27
PGND 28
EXPOSED PADDLE
9 TOFF
8 N.C.
123456 7
V_IN
+3.0V TO +5.5V
IN
LX
V_CC
SHDN
FB
PGND
AGND
COMP ^{MAX1536 REF}
PGOOD
TOFF
REFIN
V_OUT
+0.7V TO V_IN
SKIP
THIN QFN
A "+" SIGN WILL REPLACE THE FIRST PIN INDICATOR ON LEAD-FREE PACKAGES.
Idle Mode is a trademark of Maxim Integrated Products, Inc.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.