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MAX8596 Datasheet

Download or read online Maxim Integrated MAX8596 HIgh Efficiency 32V Step-Up Converter for 2 to 8 White LEDs with Ta Derating pdf datasheet.



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19-3485; Rev 2; 7/06
High-Efficiency, 36V Step-Up Converters
with T
Derating Option for 2 to 9 White LEDs
A
General Description
The MAX8595X/MAX8596X drive up to nine white LEDs
with constant current and high efficiency to provide
LCD backlighting in cell phones, PDAs, and other
handheld devices. The series connection allows the
LED currents to be identical for uniform brightness and
minimizes the number of traces to the LEDs. The
MAX8595X regulates constant LED current over the
entire temperature range. The MAX8596X features an
ambient-temperature derating function to avoid over-
driving the white LEDs during high ambient tempera-
tures, enabling higher drive current below +42°C.
A single Dual Mode™ input provides a simple means of
brightness adjustment and on/off control. Fast 1MHz
current-mode PWM operation allows for small input and
output capacitors and a small inductor while minimizing
ripple on the input supply/battery. Soft-start eliminates
inrush current during startup.
The MAX8595X/MAX8596X are available in a space-
saving, 8-pin, 3mm x 3mm TDFN package.
Cell Phones and Smart Phones
PDAs, Palmtops, and Wireless Handhelds
e-Books and Subnotebooks
White LED Display Backlighting
Dual Mode is a trademark of Maxim Integrated Products, Inc.
Typical Operating Circuit
INPUT
2.6V TO 6V
2.2µF
IN
LX
OUT
ANALOG OR
PWM DIMMING
MAX8595X
MAX8596X
CTRL
PGND
200Hz TO 200kHz
COMP
CS
GND
________________________________________________________________ Maxim Integrated Products
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.
o Up to Nine LEDs at 25mA
o Temperature Derating Function to Allow Fewer
LEDs for Same Light (MAX8596X)
o 86% Efficiency (P
o 1.7% Current-Regulation Accuracy
o Output Overvoltage Protection
o Flexible Dimming Control
Analog
Direct-PWM Internal Filter
o 1MHz PWM Switching Frequency
o 0.1µF Output Capacitor
o 12mV
P-P
o Soft-Start Eliminates Inrush Current
o 2.6V to 6V Input Range
o 0.3µA Shutdown Current
o Pin Compatible with the MAX1561 and MAX1599
o TDFN 3mm x 3mm x 0.8mm Package with
Applications
Exposed Paddle
PART
MAX8595XETA-T
MAX8595XETA+T
MAX8596XETA-T
MAX8596XETA+T
+Denotes lead-free package.
*EP = Exposed paddle.
OUTPUT
TOP VIEW
UP TO 38V
0.1µF
2 TO 9 LEDs
Features
/ P
)
LEDs
IN
Low Input Ripple
Ordering Information
PIN-
TEMP RANGE
PACKAGE
8 TDFN-EP*
-40°C to +85°C
-40°C to +85°C
8 TDFN-EP*
-40°C to +85°C
8 TDFN-EP*
-40°C to +85°C
8 TDFN-EP*
T = Tape and reel.
Pin Configuration
8
7
6
5
MAX8595X
MAX8596X
2
3
1
4
TDFN
3mm x 3mm x 0.8mm
A "+" SIGN WILL REPLACE THE FIRST
PIN INDICATOR ON LEAD-FREE PACKAGES.
PKG
CODE
T833-1
T833-1
T833-1
T833-1
1

Summary of Contents

Page 1

... T Derating Option for White LEDs A General Description The MAX8595X/MAX8596X drive up to nine white LEDs with constant current and high efficiency to provide LCD backlighting in cell phones, PDAs, and other handheld devices. The series connection allows the LED currents to be identical for uniform brightness and minimizes the number of traces to the LEDs ...

Page 2

... MAX8595X Maximum Brightness Clamp MAX8596X, Voltage V CTRL MAX8595Z CTRL Voltage for CS Maximum Brightness Clamp MAX8596Z CS Derating Function Start MAX8596Z, V Temperature 2 ___ CS to GND ...-0. Continuous Power Dissipation (T 8-Pin TDFN 3mm x 3mm 2V) (derate 24.4mW/°C above 70°C) ... 1950mW IN 0.3V) Operating Temperature Range ...-40°C to 85°C IN Junction Temperature ...150° ...

Page 3

... L 22µ 2.2µ OUT wise noted. Typical values are 25°C.) (Note 1) A PARAMETER CS Derating Function Slope MAX8596X, V CTRL Input Resistance V CTRL CTRL Dual-Mode Threshold CTRL Dual-Mode Hysteresis CTRL Shutdown Enable Delay (Note COMP Transconductance V COMP COMP Input Resistance to ...

Page 4

... R 13Ω, 4 LEDs, T COMP SENSE EFFICIENCY vs. LED CURRENT 6 LEDs 3 LEDs 8 LEDs LED CURRENT (mA) LED CURRENT vs. AMBIENT TEMPERATURE MAX8596 25mA 25°C LED A MAX8595 15mA LED - 100 TEMPERATURE (°C) SOFT-START AND SHUTDOWN RESPONSE MAX8595X toc06 ...

Page 5

... IN from IN to GND. Brightness Control Input. The voltage applied to CTRL controls LED brightness. Varying the voltage from 0.24V to 1.65V (1.72V for the MAX8596X) adjusts the brightness from dim to 100% brightness, 3 CTRL respectively. Any voltage above 1.65V (1.72V) does not increase brightness. Hold CTRL below 100mV to shut down the IC after an 8 ...

Page 6

... Derating Option for White LEDs A Detailed Description The high efficiency and small size of the MAX8595X/ MAX8596X make them ideally suited to drive up to nine series-connected LEDs. These devices operate as a boost DC-DC converter that regulates output current rather than voltage. The MAX8595X/MAX8596X provide ...

Page 7

... Output current is given by LED CTRL The V voltage range for adjusting output current is CTRL 0.24V to 1.65V (or 1.72V for the MAX8596X). To set the maximum current, calculate R SENSE its maximum as follows: For the MAX8595X 1. SENSE For the MAX8596X 1. ...

Page 8

... Due to fast switching waveforms and high-current COMP paths, careful PC board layout is required. An evalua- tion kit (MAX8596XEVKIT) is available to speed design. When laying out a board, minimize trace lengths between the IC and R COMP the input capacitor, and the output capacitor. Keep traces short, direct, and wide ...

Page 9

High-Efficiency, 36V Step-Up Converters with T Derating Option for White LEDs A (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information www.maxim-ic.com/packages.) ___ Package ...

Page 10

... 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 without notice at any time. 10 ___Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2006 Maxim Integrated Products ...

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