MAX17031 Datasheet, PDF (1/24 Pages) Maxim Integrated Products – Dual Quick-PWM Step-Down Controller with Low-Power LDO and RTC Regulator for MAIN Supplies

19-4305; Rev 0; 10/08
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Dual Quick-PWM Step-Down Controller with Low-
Power LDO and RTC Regulator for MAIN Supplies
General Description
The MAX17031 is a dual Quick-PWM™ step-down
power-supply (SMPS) controller with synchronous recti-
fication, intended for main 5V/3.3V power generation in
battery-powered systems. Low-side MOSFET sensing
provides a simple low-cost, highly efficient current
sense for valley current-limit protection. Combined with
the output overvoltage and undervoltage protection fea-
tures, this current limit ensures robust output supplies.
The 5V/3.3V SMPS outputs can save power by operat-
ing in pulse-skipping mode or in ultrasonic mode to
avoid audible noise. Ultrasonic mode forces the con-
troller to maintain switching frequencies greater than
20kHz at light loads. The SKIP input also has an accu-
rate logic threshold, allowing it to be used as a sec-
ondary feedback input to refresh an external charge
pump or secondary winding without overcharging the
output voltages.
An internal 100mA linear regulator generates the 5V
bias needed for power-up or other low-power “always-
on” suspend supplies. An internal bypass circuitry
allows automatic bypassing of the linear regulator when
the 5V SMPS is active.
The device includes independent shutdown controls
with well-defined logic thresholds to simplify power-up
and power-down sequencing. To prevent current
surges at startup, the internal voltage target is slowly
ramped up from zero to the final target over a 1ms peri-
od. To prevent the output from ringing below ground in
shutdown, the internal voltage target is ramped down
from its previous value to zero over a 1ms period. A
combined power-good (PGOOD) output simplifies the
interface with external controllers. The MAX17031 is
available in a 24-pin thin QFN (4mm x 4mm) package.
Applications
Notebook Computers
Ultra-Mobile PC
Main System Supply (5V and 3.3V Supplies)
2 to 4 Li+ Cells Battery-Powered Devices
Telecommunication
Features
o Dual Quick-PWM
o Preset 5V and 3.3V Outputs
o Internal 100mA, 5V Linear Regulator
o Internal OUT1 LDO5 Bypass Switch
o Secondary Feedback (SKIP Input) Maintains
Charge Pump
o 3.3V, 5mA Real-Time Clock (RTC) Power (Always
On)
o 2V ±1% 50µA Reference
o 6V to 24V Input Range
o Pulse-Skipping/Forced-PWM/Ultrasonic Mode
Control
o Independent SMPS and LDO5 Enable Controls
o Combined SMPS PGOOD Outputs
o Minimal Component Count
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX17031ETG+
-40°C to +85°C
24 TQFN-EP*
+Denotes a lead-free/RoHS-compliant package.
*EP = Exposed pad.
Pin Configuration
TOP VIEW
18 17 16 15 14 13
LX2 19
12 LX1
DH2 20
11 DH1
ON2 21
SKIP 22
MAX17031
10 ON1
9 PGOOD
OUT2 23
+
ILIM2 24
*EP
8 ILIM1
7 OUT1
12 3 4 56
Quick-PWM is a trademark of Maxim Integrated Products, Inc.
*EXPOSED PAD.
THIN QFN
4mm × 4mm
________________________________________________________________ Maxim Integrated Products 1
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.