Rainbow Electronics MAX8514 - Manual

General Description
The MAX8513/MAX8514 integrate a voltage-mode
PWM step-down DC-DC controller and two LDO con-
trollers, a voltage monitor, and a power-on reset for the
lowest-cost power-supply and monitoring solution for
xDSL modems, routers, gateways, and set-top boxes.
The DC-DC controller switching frequency can be set
with an external resistor from 300kHz to 1.4MHz, to allow
for the optimization of cost, size, and efficiency. For noise-
sensitive applications, the DC-DC controller can also be
synchronized to an external clock, minimizing noise inter-
ference. Operation above 1.1MHz reduces noise for high
data-rate xDSL applications. An adjustable soft-start and
adjustable foldback current limit provide reliable startup
and fault protection. The DC-DC controller output voltage
can be set externally to a voltage from 1.25V to 5.5V.
Current limiting is accomplished by inductor current sens-
ing for improved efficiency, or by an external sense resis-
tor for better accuracy.
The MAX8513/MAX8514s’ first LDO controller is
designed to provide a low-cost, high-current regulated
output from 0.8V to 5.5V using an N-channel MOSFET or
a low-current output using a low-cost NPN transistor. The
MAX8513’s second regulator can be used to generate
0.8V to 27V output with a low-cost PNP transistor. Both
LDO regulators can operate either from the DC-DC con-
troller output or from a higher voltage derived with a fly-
back overwinding on the DC-DC converter inductor. The
MAX8514’s second LDO regulator is designed to pro-
vide a negative output with an NPN transistor.
A sequence input allows the outputs to either power up
together, or for the DC-DC regulator to power up first
and each LDO controller to power up in sequence. An
input power-fail output (PFO) is provided for input
power-fail warning, such as in dying-gasp applications.
A power-on reset circuit with a 140ms delay is also
included to indicate when all outputs have achieved
regulation and stabilized.
Applications
xDSL, Cable, ISDN Modems, and Routers
Wireless Routers
Set-Top Boxes
Automotive Dashboard Electronics
Features
♦ Low-Cost DC-DC Controller with Two LDOs
♦ Wide Input Range: 4.5V to 28V
♦ 300kHz to 1.4MHz Adjustable Switching
Frequency
♦ Low Noise for High Data-Rate xDSL Applications
♦ Synchronizable to External Clock
♦ Adjustable Soft-Start
♦ Lossless Adjustable Foldback Current Limit
♦ Power-On Reset with 140ms Delay
♦ Adjustable Input Power-Fail Warning for Dying
Gasp
♦ Selectable Output-Voltage Sequencing or
Output-Voltage Tracking
MAX8513/MAX8514
Wide-Input, High-Frequency, Triple-Output Supplies
with Voltage Monitor and Power-On Reset
________________________________________________________________ Maxim Integrated Products 1
STEP-
DOWN
CONTROLLER
V IN
(4.5V TO 28V)
V OUT1
(1.25V TO 5.5V)
V OUT2
(0.8V TO V OUT1 )
V OUT3
(0.8V TO 27V)
LDO
CONTROLLER 1
LDO
CONTROLLER 2
OUTPUT
POWER-ON RESET
INPUT POWER-
FAIL MONITOR
MAX8513
SYNC
ON
OFF
Functional Diagram
Ordering Information
19-3178; Rev 0; 2/04
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.
EVALUATION KIT
AVAILABLE
PART TEMP RANGE PIN-PACKAGE
MAX8513 EEI -40
°
C to +85
°
C 28 QSOP
MAX8514 EEI -40
°
C to +85
°
C 28 QSOP
MAX8514AEI -40
°
C to +125
°
C 28 QSOP
Pin Configurations appear at end of data sheet.