Rainbow Electronics MAX8737 - Manual

General Description
The MAX8737 dual high-power linear regulator con-
trollers use external n-channel MOSFETs to generate
two independent low-voltage supplies for notebook
computers. The MAX8737 delivers low output voltages
from 0.5V to 2.5V (±5mV no-load accuracy). The exter-
nal components allow scalable current design with
loads up to 5A with excellent load regulation (1%). The
regulator operates from a low input voltage, which also
reduces the power dissipation in the external n-channel
MOSFET. The controller powers the external MOSFET
gate driver from the standard 5V system supply.
The MAX8737 includes current and thermal limits to
prevent damage to the linear regulator. The MAX8737
uses an external resistive divider to fold back the cur-
rent limit, reducing the overall power dissipation. The
MAX8737 uses an external resistive-divider in series
with the current-sense input (CS_), providing foldback
current-limit protection, and effectively reducing the
short-circuit power dissipation.
An output undervoltage timeout is available for low-cost
applications that omit the current-sense resistor. The
output undervoltage (UVP) timing depends on the mag-
nitude of the voltage at V
OUT
. The UVP detects and
shuts down the LDO if the output voltage drops out of
regulation. The controller uses an adjustable reference
input (REFIN_) to set the nominal output voltage
(V
OUT_ ), which minimizes the cost and makes the sta-
bility independent of the output voltage.
Each linear regulator features an adjustable soft-start
function, and generates a delayed power-good
(PGOOD) signal that signals when the linear regulator
is in regulation. The MAX8737 is a low-cost solution
requiring few external components and is available in a
small, 4mm x 4mm, 16-pin thin QFN package.
Applications
Notebook and Desktop Computers
Point-of-Load Regulators
V MCH and V CCP CPU Supplies
Low-Voltage Bias Supplies
Servers
Features
♦ Low-Cost Dual Linear Regulators
♦ Output Voltage Accuracy ±5mV
♦ Independent 0.5V to 2.5V Reference Inputs
♦ Foldback Current-Limit Protection
♦ Output Undervoltage-Lockout Protection
♦ Thermal Limit (Internal Sensor)
♦ 1.0V to 5.5V Input Supply Voltage (External FET
Drain)
♦ 5V Bias Supply Voltage
♦ Independent Power-Good Open-Drain Outputs
♦ Independent Enable Inputs
♦ Soft-Shutdown Output Discharge
♦ Low Supply Current (0.5mA)
♦ 5µA (max) Shutdown Supply Current
MAX8737
Dual, Low-Voltage Linear Regulator Controllers
with External MOSFETs
________________________________________________________________ Maxim Integrated Products 1
16
1 2 3 4
12 11 10 9
15
14
13
5
6
7
8
DRV1
GND
N.C.
DRV2
N.C. CS2 OUT2 REFIN2
CS1
OUT1
REFIN1
PGOOD2
PGOOD1
EN2
EN1
V
CC
TOP VIEW
MAX8737
4mm x 4mm TQFN
Pin Configuration
19-3705; Rev 0; 5/05
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
Ordering Information
PART TEMP RANGE PIN-PACKAGE
MAX8737ETE -40°C to +85°C 16 Thin QFN-EP* 4mm x 4mm
MAX8737ETE+ -40°C to +85°C 16 Thin QFN-EP* 4mm x 4mm
*EP = Exposed pad.
+ Denotes lead-free packaging.