Rainbow-electronics MAX8758 Bedienungsanleitung

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General Description
The MAX8758 includes a high-performance step-up regu-
lator, a high-speed operational amplifier, and a logic-
controlled, high-voltage switch-control block with pro-
grammable delay. The device is optimized for thin-film
transistor (TFT) liquid-crystal display (LCD) applications.
The step-up DC-DC regulator provides the regulated sup-
ply voltage for the panel source driver ICs. The converter
is a high-frequency (640kHz/1.2MHz), current-mode regu-
lator with an integrated 14V n-channel power MOSFET.
The high-switching frequency allows the use of ultra-small
inductors and ceramic capacitors. The current-mode con-
trol architecture provides fast transient response to pulsed
loads. The regulator achieves efficiencies over 85% by
bootstrapping the supply rail of the internal gate driver
from the step-up regulator output. The step-up regulator
features undervoltage lockout (UVLO), soft-start, and
internal current limit. The high-current operational amplifier
is designed to drive the LCD backplane (VCOM). The
amplifier features high output current (±150mA), fast slew
rate (7.5V/µs), wide bandwidth (12MHz), and rail-to-rail
inputs and outputs.
The MAX8758 is available in a 24-pin, 4mm x 4mm, thin
QFN package with a maximum thickness of 0.8mm for
ultra-thin LCD panels. The device operates over the
-40°C to +85°C temperature range.
Applications
Notebook Displays
LCD Monitors
Features
1.8V to 5.5V Input Voltage Range
Input Undervoltage Lockout
0.5mA Quiescent Current
640kHz/1.2MHz Current-Mode Step-Up Regulator
Fast Transient Response
High-Accuracy Output Voltage (1.5%)
Built-In 14V, 2.5A, 115m MOSFET
High Efficiency
Programmable Soft-Start
Current Limit with Lossless Sensing
Timer-Delay Fault Latch
High-Speed Operational Amplifier
±150mA Output Current
7.5V/µs Slew Rate
12MHz, -3dB Bandwidth
Rail-to-Rail Inputs/Outputs
Dual-Mode™, Logic-Controlled, High-Voltage
Switch with Programmable Delay
Thermal-Overload Protection
24-Pin, 4mm x 4mm, Thin QFN Package
MAX8758
Step-Up Regulator with Switch Control and
Operational Amplifier for TFT LCD
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
V
MAIN
TO VCOM
BACKPLANE
V
GON
FROM TCON
V
IN
V
GOFF
IN
FREQ
SHDN
COMP
LDO
FB
LX
GND
PGND
OUT
SUPB
GON
DRN
CTL
MODE
SS
POSB
NEGB
OUTB
THR
DLP
SRC
MAX8758
Simplified Operating Circuit
19-3699; 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.
PART
TEMP RANGE
PIN-PACKAGE
MAX8758ETG
-40°C to +85°C
24 Thin QFN-EP*
4mm x 4mm
Pin Configuration appears at end of data sheet.
DualMode is a trademark of Maxim Integrated Products, Inc.
*EP = Exposed pad.
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1 2 3 4 5 6 ... 19 20

Inhaltsverzeichnis

Seite 1 - Simplified Operating Circuit

General DescriptionThe MAX8758 includes a high-performance step-up regu-lator, a high-speed operational amplifier, and a logic-controlled, high-voltag

Seite 2 - ELECTRICAL CHARACTERISTICS

MAX8758Typical Operating CircuitThe typical operating circuit (Figure 1) of the MAX8758is a power-supply solution for TFT LCD panels in note-book comp

Seite 3

Detailed DescriptionThe MAX8758 is designed primarily for TFT LCD panelsused in notebook computers. It contains a high-perfor-mance step-up regulator,

Seite 4

MAX8758The internal n-channel power MOSFET reduces thenumber of external components. The supply rail of theinternal gate driver is bootstrapped to the

Seite 5 - Output Voltage Swing Low

The soft-start timing can be adjusted with an externalcapacitor connected between SS and GND. After thestep-up regulator is enabled, the SS pin is imm

Seite 6 - = 8.5V, FREQ = SHDN = IN, T

MAX8758Activate the first mode by connecting MODE to LDO.When CTL is logic high, Q1 turns on and Q2 turns off,connecting GON to SRC. When CTL is logic

Seite 7

MAX8758Step-Up Regulator with Switch Control andOperational Amplifier for TFT LCD_____________________________________________________________________

Seite 8

MAX8758In Figure 1’s Typical Operating Circuit, the LCD’s gate-on and gate-off voltages are generated from two unreg-ulated charge pumps driven by the

Seite 9 - Pin Description

Step-Up Regulator Input Capacitor SelectionThe input capacitor reduces the current peaks drawnfrom the input supply and reduces noise injection intoth

Seite 10 - Typical Operating Circuit

MAX8758Charge-Pump Flying CapacitorsIncreasing the flying capacitor (C6, C17, C18) valuelowers the effective source impedance and increasesthe output-

Seite 11 - Detailed Description

MAX8758Step-Up Regulator with Switch Control andOperational Amplifier for TFT LCD_____________________________________________________________________

Seite 12 - Table 2. Component Suppliers

MAX8758Step-Up Regulator with Switch Control andOperational Amplifier for TFT LCD2 ___________________________________________________________________

Seite 13 - Table 3. Frequency Selection

MAX8758Step-Up Regulator with Switch Control andOperational Amplifier for TFT LCDMaxim cannot assume responsibility for use of any circuitry other tha

Seite 14 - Design Procedure

MAX8758Step-Up Regulator with Switch Control andOperational Amplifier for TFT LCD_____________________________________________________________________

Seite 15 - Figure 4. Switch Control

MAX8758Step-Up Regulator with Switch Control andOperational Amplifier for TFT LCD4 ___________________________________________________________________

Seite 16

PARAMETER CONDITIONSMINTYPMAXUNITSFREQ = GND 91 99Oscillator Maximum Duty CycleFREQ = IN 88 96%FB Regulation Voltage1.220 1.252VFB Transconductance ∆I

Seite 17 - Charge Pumps

MAX8758Step-Up Regulator with Switch Control andOperational Amplifier for TFT LCD6 ___________________________________________________________________

Seite 18 - PC Board Layout and Grounding

MAX8758Step-Up Regulator with Switch Control andOperational Amplifier for TFT LCD_____________________________________________________________________

Seite 19 - Pin Configuration

MAX8758Step-Up Regulator with Switch Control andOperational Amplifier for TFT LCD8 ___________________________________________________________________

Seite 20 - Package Information

MAX8758Step-Up Regulator with Switch Control andOperational Amplifier for TFT LCD_____________________________________________________________________

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