max5025eutt Maxim Integrated Products, Inc., max5025eutt Datasheet

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max5025eutt

Manufacturer Part Number
max5025eutt
Description
500khz, 36v Output, Sot23, Pwm Step-up Dc-dc Converters
Manufacturer
Maxim Integrated Products, Inc.
Datasheet
The MAX5025–MAX5028 constant-frequency, pulse-
width modulating (PWM), low-noise boost converters
are intended for low-voltage systems that often need a
locally generated high voltage. These devices are
capable of generating low-noise, high output voltages
required for varactor diode biasing in TV tuners, set-top
boxes, and PCI cable modems. The MAX5025–
MAX5028 operate from as low as 3V and switch at
500kHz.
The constant-frequency, current-mode PWM architec-
ture provides for low output noise that is easy to filter. A
40V lateral DMOS device is used as the internal power
switch, making the devices ideal for boost converters
up to 36V. The MAX5025/MAX5026 adjustable versions
require the use of external feedback resistors to set the
output voltage. The MAX5027/MAX5028 offer a fixed
30V output. These devices are available in a small, 6-
pin SOT23 package.
19-2239; Rev 1; 12/01
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
V
CC
V
CC
= 4.5V TO 11V
= 3V TO 11V
TV Tuner Power Supply
Low-Noise Varactor Diode Biasing
Set-Top Box Tuner Power Supply
PCI Cable Modem
Voice-Over-Cable
LCD Power Supply
Avalanche Photodiode Biasing
(MAX5027)
(MAX5028)
Typical Operating Circuit
500kHz, 36V Output, SOT23, PWM Step-Up
C1
________________________________________________________________ Maxim Integrated Products
V
SHDN
PGND
General Description
CC
MAX5027
MAX5028
L1
GND
LX
FB
Applications
D1
C2
V
30V
OUT
o Input Voltage Range:
o Wide Output Voltage Range: V
o Output Power: 120mW (max)
o User-Adjustable Output Voltage with
o Fixed 30V Output Voltage: MAX5027/MAX5028
o Internal 1.3Ω (typ), 40V Switch
o Constant PWM Frequency Provides Easy Filtering
o 500kHz (typ) Switching Frequency
o 1µA (max) Shutdown Current
o Small, 6-Pin SOT23 Package
Selector Guide appears at end of data sheet.
MAX5025EUT-T
MAX5026EUT-T
MAX5027EUT-T
MAX5028EUT-T
3V to 11V (MAX5026/MAX5028)
4.5V to 11V (MAX5025/MAX5027)
MAX5025/MAX5026 Using External Feedback
Resistors
in Low-Noise Applications
TOP VIEW
PA RT
DC-DC Converters
PGND
GND
FB
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
RANGE
1
2
3
TEMP.
Ordering Information
SOT23-6
MAX5025–
MAX5028
Pin Configuration
PIN-
PA CKA GE
6 SOT23-6
6 SOT23-6
6 SOT23-6
6 SOT23-6
CC
6
5
4
to 36V
LX
V
SHDN
CC
Features
MARK
AATM
AATK
AATL
AATJ
TOP
1

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max5025eutt Summary of contents

Page 1

Rev 1; 12/01 500kHz, 36V Output, SOT23, PWM Step-Up General Description The MAX5025–MAX5028 constant-frequency, pulse- width modulating (PWM), low-noise boost converters are intended for low-voltage systems that often need a locally generated high voltage. These devices are capable of ...

Page 2

Output, SOT23, PWM Step-Up DC-DC Converters ABSOLUTE MAXIMUM RATINGS V to GND ............................................................-0.3V to +12V CC PGND to GND .......................................................-0.1V to +0. GND (MAX5025/MAX5026)...............-0. GND (MAX5027/MAX5028)...........................-0.3V to +40V SHDN to GND.............................................-0.3V to ...

Page 3

Output, SOT23, PWM Step-Up ELECTRICAL CHARACTERISTICS (continued) = 5V, SHDN = -40°C to +85°C, unless otherwise noted. Typical values are PARAMETER SYMBOL FB Set Point FB Input Bias ...

Page 4

Output, SOT23, PWM Step-Up DC-DC Converters ( 30V +25°C, unless otherwise noted.) CC OUT A EFFICIENCY vs. LOAD CURRENT (V = 12V) OUT MAX5026 30 V ...

Page 5

Output, SOT23, PWM Step- 5V 30V +25°C, unless otherwise noted.) CC OUT A EXITING SHUTDOWN OUTPUT VOLTAGE 20V/div 5V INDUCTOR CURRENT 50mA/div SHUTDOWN VOLTAGE 5V/div 2ms/div MAX5026 5V ...

Page 6

Output, SOT23, PWM Step-Up DC-DC Converters ( 30V +25°C, unless otherwise noted.) CC OUT A HEAVY-LOAD SWITCHING WAVEFORM WITHOUT RC FILTER V OUT 5mV/div AC-COUPLED LX PIN 20V/div I L 200mA/div 1µs/div ...

Page 7

Output, SOT23, PWM Step- 5V 30V +25°C, unless otherwise noted.) CC OUT A SWITCH ON-RESISTANCE vs. TEMPERATURE 3 1.5 1.0 0.5 -40 ...

Page 8

Output, SOT23, PWM Step-Up DC-DC Converters PIN NAME MAX5025/ MAX5027/ MAX5026 MAX5028 1 1 PGND 2 2 GND 3 — FB — SHDN Detailed Description The MAX5025–MAX5028 ...

Page 9

Output, SOT23, PWM Step-Up ULVO OSCILLATOR MAIN PWM COMPARATOR CONTROL LOGIC +A REF +C 2 GND -C CURRENT- LIMIT COMPARATOR Figure 1. Functional Diagram   OUT ...

Page 10

Output, SOT23, PWM Step-Up DC-DC Converters For a design in which 4mA, η = 0.5, and T = 2µ 87µH UPPER and L = 12µH. LOWER For a worst-case scenario ...

Page 11

Output, SOT23, PWM Step-Up trace lengths to reduce stray capacitance, trace resis- tance, and radiated noise. The trace between the out- put voltage-divider (MAX5025/MAX5026) and the FB pin must be kept short, as well as the trace between ...

Page 12

Output, SOT23, PWM Step-Up DC-DC Converters PART OUTPUT MAX5025 Adjustable MAX5026 Adjustable MAX5027 Fixed 30V MAX5028 Fixed 30V 12 ______________________________________________________________________________________ FREQUENCY FB SET POINT TOLERANCE TOLERANCE ±5% -31% to +100% ±3% -18% to +34% ±5% -31% to +100% ...

Page 13

Output, SOT23, PWM Step-Up Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications ...

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