MAX8597 Datasheet, PDF (1/24 Pages) Maxim Integrated Products – Low-Dropout, Wide-Input-Voltage, Step-Down Controllers

19-3505; Rev 0; 11/04
EVAALVUAAILTAIOBNLEKIT
Low-Dropout, Wide-Input-Voltage,
Step-Down Controllers
General Description
The MAX8597/MAX8598/MAX8599 voltage-mode PWM
step-down controllers are designed to operate from a
4.5V to 28V input supply and generate output voltages
down to 0.6V. A proprietary switching algorithm stretch-
es the duty cycle to >99.5% for low-dropout design.
Unlike conventional step-down regulators using a p-
channel high-side MOSFET to achieve high duty cycle,
the MAX8597/MAX8598/MAX8599 drive n-channel
MOSFETs resulting in high efficiency and high-current-
capability designs.
The MAX8597 is available in a 20-pin thin QFN pack-
age and is designed for applications that use an analog
signal to control the output voltage with an adjustable
offset, such as DC fan-speed control. This is achieved
with an internal uncommitted operational amplifier. The
MAX8597 is also targeted for tracking output-voltage
applications for chipsets, ASIC and DSP cores, and I/O
supplies. The MAX8598/MAX8599 are available in a 16-
pin thin QFN package and do not have the uncommitted
operational amplifier, reference input, and reference out-
put, but offer an open-drain, power-OK output.
The MAX8597/MAX8598/MAX8599 allow startup with
prebias voltage on the output for applications where a
backup supply or a tracking device may charge the
output capacitor before the MAX8597/MAX8598/
MAX8599 are enabled. In addition, the MAX8599 fea-
tures output overvoltage protection.
These controllers also feature lossless high-side peak
inductor current sensing, adjustable current limit, and
hiccup-mode short-circuit protection. Switching fre-
quency is set with an external resistor from 200kHz to
1.4MHz. This wide frequency range combined with a
wide-bandwidth error amplifier enables the loop com-
pensation scheme to give the user ample flexibility to
optimize for cost, size, and efficiency.
Applications
Nonisolated Power Modules
Variable-Speed DC Fan Power Supplies
(MAX8597)
Tracking Power Supplies (MAX8597)
Chipset Power Supplies
Features
♦ Low Dropout with >99.5% Duty Cycle
♦ Lossless High-Side Current Limit
♦ Wide 4.5V to 28V Input Range
♦ Dynamic Output Voltage Adjustment with
Adjustable Offset (MAX8597)
♦ Remote Voltage Sensing for Both Positive and
Negative Rails (MAX8597)
♦ Tracking Output Through REFIN (MAX8597)
♦ Adjustable Switching Frequency from 200kHz to
1.4MHz
♦ Adjustable Soft-Start
♦ Prebias Startup
♦ Enable and Power-OK (MAX8598/MAX8599) for
Flexible Sequencing
♦ 25MHz Error Amplifier
♦ Adjustable Hiccup Current Limit for Output
Short-Circuit Protection
♦ Output Overvoltage Protection (MAX8599)
♦ Small, Low-Profile Thin QFN Package
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX8597ETP+
-40°C to +85°C
20 Thin QFN 4mm x 4mm
(T2044-3)
MAX8598ETE+
-40°C to +85°C
16 Thin QFN 4mm x 4mm
(T1644-4)
MAX8599ETE+
-40°C to +85°C
16 Thin QFN 4mm x 4mm
(T1644-4)
+Denotes lead-free package.
Pin Configurations
TOP VIEW
15 14 13 12 11
ILIM 16
10 VL
FREQ 17
9 V+
AOUT 18
MAX8597
8 REFOUT
AIN- 19
7 EN
AIN+ ²⁰
6 COMP
1234 5
THIN QFN
4mm x 4mm
Pin Configurations continued at end of data sheet
________________________________________________________________ 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.