MAX8798EVKIT [MAXIM]

Resistor-Adjustable Switching Regulator and Op-Amp Output Range;


型号：	MAX8798EVKIT
厂家：	MAXIM INTEGRATED PRODUCTS
描述：	Resistor-Adjustable Switching Regulator and Op-Amp Output Range
文件：	总13页 (文件大小：250K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

19-1004; Rev 1; 9/08

MAX8798 Evaluation Kit/Evaluation System

Evluate:MAX798

General Description

Features

The MAX8798 evaluation system (EV system) consists

of the MAX8798 evaluation kit (EV kit) and the Maxim

CMAXQUSB command module. A Windows^®2000/XP/

Vista^®-compatible software is also available for use with

the EV system (MAX8798EVCMAXQU+) and can be

downloaded from www.maxim-ic.com/evkitsoftware.

o +1.8V to +6V Input Range

o Output Voltages

+8V Output at 300mA (+2.2V Input Step-Up

Switching Regulator)

+21V Output at 20mA (Positive Charge Pump)

-13V Output at 20mA (Negative Charge Pump)

150mA High-Current Op-Amp Output

The MAX8798 EV kit (MAX8798EVKIT+) is a fully

assembled and tested surface-mount printed-circuit

board (PCB) that provides the features required for

active-matrix, thin-film transistor (TFT) liquid-crystal dis-

plays (LCDs). The EV kit contains a step-up switching

regulator, positive two-stage charge pump, negative

two-stage charge pump, digitally adjustable VCOM cali-

bration device with nonvolatile memory, SMBus™-com-

patible interface, high-speed operational amplifier (op

amp), and high-voltage, level-shifting scan driver for

thin TFT-LCD applications.

o Resistor-Adjustable Switching Regulator and Op-

Amp Output Range

o Digitally Programmable Op-Amp Output Voltage

o +35V to -25V High-Voltage Level-Shifting Drivers

o Greater than 85% Efficiency (Step-Up Switching

Regulator)

o 1.2MHz Step-Up Switching Frequency

o SMBus-Compatible Interface

o Windows 2000/XP/Vista (32-Bit)-Compatible

The EV kit operates from a DC supply voltage from

+1.8V to +6V. The step-up switching regulator is con-

figured for a +8V output providing at least 300mA from

a +2.2V input. The positive charge pump is configured

for a +21V output providing at least 20mA. The nega-

tive charge pump is configured for a -13V output pro-

viding at least 20mA. The op amp is capable of provid-

ing up to 1ꢀ0mA peak and features a programmable

output voltage initially configured for +3.2V. The high-

voltage level-shifting scan driver buffers inputs from

STV, CPV, and OE pads and shifts them to a desired

level to drive TFT-LCD row logic.

Software

o 1.2mm Low-Profile Surface-Mount Components

o Lead-Free and RoHS Compliant

o Fully Assembled and Tested

Ordering Information

PART

TYPE

EV Kit

MAX8798EVKIT+

MAX8798EVCMAXQU+

+Denotes lead-free and RoHS compliant.

EV System

The MAX8798 EV kit demonstrates low quiescent cur-

rent and high efficiency (> 8ꢀ%) for maximum battery

time per charge. Operation at 1.2MHz allows the use of

tiny surface-mount components. The MAX8798 thin

QFN package (0.8mm max height), with low-profile

external components, allows this circuit to be less than

1.2mm high.

Note: The Maxim command module (CMAXQUSB) is required

when using the MAX8798 EV kit software.

Component List

DESIGNATION QTY

DESCRIPTION

The Maxim CMAXQUSB command module provides

the SMBus-compatible interface and is connected to a

PC through the universal serial bus (USB) port. The

MAX8798 EV kit software provides a graphical user

interface (GUI) for exercising the MAX8798 features.

10µF 20%, 6.3V XꢀR ceramic

capacitor (0603)

TDK C1608XꢀR0J106M or equivalent

C2, C18,

C19, C20

Not installed, ceramic capacitors

(0603)

220pF 10%, ꢀ0V X7R ceramic

capacitor (0603)

Murata GRM188R71H221KA

TDK C1608X7R1H221K or equivalent

0.047µF 10%, ꢀ0V XꢀR ceramic

capacitor (0603)

Murata GRM188R71H473K

TDK C1608X7R1H473K or equivalent

Windows and Windows Vista are registered trademarks of

Microsoft Corp.

SMBus is a trademark of Intel Corp.

________________________________________________________________ Maxim Integrated Products

For pricing, delivery, and ordering information, please contact Maxim Direct 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

MAX8798 Evaluation Kit/Evaluation System

Component List (continued)

DESIGNATION QTY

DESCRIPTION

DESIGNATION QTY

DESCRIPTION

0.22µF 20%, 16V XꢀR ceramic

capacitor (0603)

TDK C1608XꢀR1C224M or equivalent

Dual-row (2 x 10) right-angle

receptacle

JU1, JU2

Cꢀ

2-pin headers

1µF 20%, 10V XꢀR ceramic

capacitors (0603)

TDK C1608XꢀR1A10ꢀM or equivalent

3.6µH, 1.8A power inductor

Sumida CMD6D11BHPNP-3R6MC

C6, C7

OECON

R1, R6, R7

Not installed, test point

0.1µF 10%, ꢀ0V X7R ceramic

capacitors (0603)

TDK C1608X7R1H104K or equivalent

200kΩ 1% resistors (0603)

36.ꢀkΩ 1% resistor (0603)

60.4kΩ 1% resistor (0603)

10Ω ꢀ% resistor (0603)

100kΩ ꢀ% resistors (0603)

24.9kΩ 1% resistor (080ꢀ)

20kΩ ꢀ% resistor (0603)

200Ω ꢀ% resistors (0603)

10kΩ ꢀ% resistors (0603)

C8–C16

C17

Not installed, electrolytic capacitor

(6.3mm x ꢀmm)

Rꢀ, R1ꢀ

4.7µF 10%, 16V XꢀR ceramic

capacitors (1206)

Murata GRM319R61C47ꢀKA88D

TDK C3216XꢀR1C47ꢀK

C21, C22

C23

Evluate:MAX798

R10, R11

R12, R13, R14

Not installed, ceramic capacitor

(1206)

Not installed, resistor—short

(PC trace) (0603)

1A, 30V Schottky diode (S-Flat)

Central CMMSH1-40LEADFREE

Nihon EP10QY03

R16

Maxim internal-switch boost regulator

MAX8798ETX+

Toshiba CRS02(TE8ꢀL)

(36-pin thin QFN, 6mm x 6mm)

200mA, 100V dual diodes (SOT23)

Fairchild MMBD4148SE (Top Mark: D4)

Central CMPD7000LEADFREE

(Top Mark: CꢀC)

—

Shunts

D2–Dꢀ

PCB: MAX8798 Evaluation Kit+

Component Suppliers

SUPPLIER

PHONE

WEBSITE

Central Semiconductor

Fairchild Semiconductor

631-43ꢀ-1110

888-ꢀ22-ꢀ372

770-436-1300

847-843-7ꢀ00

847-ꢀ4ꢀ-6700

847-803-6100

949-623-2900

www.centralsemi.com

www.fairchildsemi.com

www.murata-northamerica.com

www.niec.co.jp

Murata Electronics North America, Inc.

Nihon Inter Electronics Corp.

Sumida Corp.

www.sumida.com

TDK Corp.

www.component.tdk.com

www.toshiba.com/taec

Toshiba America Electronic Components, Inc.

Note: Indicate that you are using the MAX8798 when contacting these component suppliers.

MAX8798 EV Kit Files

FILE

DESCRIPTION

INSTALL.EXE

MAX8798.EXE

Installs the EV kit files on your computer

Application program

USB device driver file

FTD2XX.INF

UNINST.INI

Uninstalls the EV kit software

USB driver installation help file

TROUBLESHOOTING_USB.PDF

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MAX8798 Evaluation Kit/Evaluation System

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2) To enable the MAX8798, ensure that a shunt is

Quick Start

Recommended Equipment

Before beginning, the following equipment is needed:

installed on jumper JU1 of the MAX8798 EV kit.

3) Visit www.maxim-ic.com/evkitsoftware to down-

load the latest version of the MAX8798 EV kit soft-

•

+1.8V to +6V, 2A DC power supply for PIN

ware, MAX8798Rxx.ZIP. Save the EV kit software to

a temporary folder and uncompress the ZIP file.

MAX8798 EV system

MAX8798 EV kit

4) Install the EV kit software on your computer by run-

ning the INSTALL.EXE program inside the tempo-

rary folder. The program files are copied and icons

are created in the Windows Start | Programs

menu.

CMAXQUSB command module (USB cable

included)

•

A user-supplied Windows 2000/XP/Vista-compatible

PC with a spare USB port

ꢀ) Carefully connect the boards by aligning the

MAX8798 EV kit’s 20-pin J1 connector with the

CMAXQUSB board’s 20-pin P3 connector. Gently

press them together. The two boards should be

flush against each other.

Voltmeter

Note: In the following sections, software-related items

are identified by bolding. Text in bold refers to items

directly from the EV kit software. Text in bold and under-

lined refers to items from the Windows operating system.

Hardware Procedure

The MAX8798 EV kit is fully assembled and tested.

Follow the steps below to verify board operation.

Caution: Do not turn on the power supply until all

connections are completed.

1) Verify that a shunt is installed across jumper JU1.

2) Verify that no shunt is installed across jumper JU2.

6) Connect the USB cable from the PC to the

CMAXQUSB board. A Building Driver Database

window pops up in addition to a New Hardware

Found message when installing the USB driver for

the first time. If you do not see a window that is

similar to the one described above after 30s,

remove the USB cable from the board and recon-

nect it. Administrator privileges are required to

install the USB device driver on Windows

2000/XP/Vista.

3) Connect the positive terminal of the power supply to

the PIN pad. Connect the negative terminal of the

power supply to the GND pads closest to PIN.

7) Follow the directions of the Add New Hardware

Wizard to install the USB device driver. Choose the

Search for the best driver for your device option.

Specify the location of the device driver to be

C:\Program Files\MAX8798 (default instal-

lation directory) using the Browse button. During

device driver installation, Windows may show a

warning message indicating that the device driver

Maxim uses does not contain a digital signa-

ture. This is not an error condition and it is safe

to proceed with installation. Refer to the

TROUBLESHOOTING_USB.PDF document for

additional information.

4) Turn on the power supply and verify that the step-

up switching regulator output (MAIN) is +8V.

ꢀ) Verify that the gate-on supply (GON) is approxi-

mately +21V.

6) Verify that the gate-off supply (GOFF) is approxi-

mately -13V.

7) Verify that the output of the high-speed op amp

(VCOM) is approximately +3.2V.

For instructions on selecting the step-up switching regu-

lator feedback and op-amp divider resistors for other out-

put voltages, see the Output-Voltage Selection section.

8) Start the MAX8798 EV kit software by opening its

icon in the Start | Programs menu.

9) Normal device operation is verified when MAX8798

connected is displayed in the status bar on the

MAX8798 EV kit main window (Figure 1).

Software Procedure

With the EV kit powered on, perform the following steps

to verify software operation:

1) On the CMAXQUSB command module, ensure that

the shunt on jumper JU1 is in the +3.3V position.

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MAX8798 Evaluation Kit/Evaluation System

Evluate:MAX798

Figure 1. MAX8798 EV Kit Software Main Window

The op-amp output (VCOM) is SMBus programmable

Detailed Description of Hardware

and is configured for an output-voltage range of +2.4V

The MAX8798 EV kit contains a step-up switching regu-

to +4V. VCOM can source or sink peak current up to

lator, positive two-stage charge pump, negative two-

1ꢀ0mA. The output-voltage range can be reconfigured

stage charge pump, digitally adjustable VCOM calibra-

to other voltages with voltage-divider resistors R6 and

tion device with nonvolatile memory, SMBus-compati-

R7. Refer to the Setting the VCOM Adjustment Range

ble interface, high-speed operational amplifier (op

section in the MAX8798 IC data sheet for more details.

amp), and high-voltage level-shifting scan driver for

The MAX8798 includes a 3-channel, high-voltage level-

shifting driver for driving row-driver functions on the

panel glass. CKV, CKVB, and STVP pads are the out-

puts of the driver. The outputs swing between GON

and GOFF according to the input logic levels on the

STV, CPV, and OE pads and the IC’s internal logic.

Refer to the High-Voltage Level-Shifting Scan Driver

section in the MAX8798 IC data sheet for more details.

thin TFT-LCD applications. The EV kit can operate from

a single DC power supply between +1.8V to +6V that

can provide at least 2A.

As configured, the step-up switching regulator (MAIN)

generates a +8V output and can provide at least

200mA from a +1.8V input. It also provides at least

300mA from a +2.2V input and 600mA from a +4.ꢀV

input. The step-up switching-regulator output voltage

can be adjusted up to +18V with different feedback

resistors (see the Output-Voltage Selection section).

Jumper Selection (JU1, JU2)

The MAX8798 EV kit incorporates jumper JU1 to

enable/disable the IC outputs and jumper JU2 to

enable/disable write protection. When write protection

is enabled, all SMBus commands are ignored by the

device. This prevents device detection and changing of

the VCOM calibrator settings. See Table 1 for jumper

JU1 functions and Table 2 for jumper JU2 functions.

The GON consists of two positive charge-pump stages

to generate approximately +21V and can provide greater

than 20mA. The GOFF consists of two negative charge-

pump stages to generate approximately -13V and can

provide greater than 20mA. Loading GON and GOFF

reduces the available MAIN current proportionally.

_______________________________________________________________________________________

MAX8798 Evaluation Kit/Evaluation System

Evluate:MAX798

Table 1. Jumper JU1 Functions

SHUNT POSITION

SHDN PIN

EV KIT OUTPUTS

Installed*

SHDN connected to PIN

Outputs enabled (MAIN = +8V)

Outputs disabled (MAIN ≈ PIN)

Not installed

SHDN connected to GND through Rꢀ

*Default position.

Table 2. Jumper JU2 Functions

SHUNT POSITION

WPN PIN

VCOM CALIBRATOR WRITE PROTECTION

Installed

WPN connected to GND

Enabled

Disabled

Not installed*

*Default position.

WPN connected to VDD through R1ꢀ

priate DAC setting into the DAC edit box. The DAC set-

ting can be set from 0x00 (VCOM ) to 0x7F

Output-Voltage Selection

The MAX8798 EV kit’s step-up switching-regulator out-

put (MAIN) is set to +8V by feedback resistors R1 and

R2. To generate output voltages other than +8V (up to

+18V), select different external voltage-divider resis-

tors, R1 and R2.

MAX

(VCOM

). The DAC setting is written to the device by

MIN

pressing the Load DAC button (Figure 1).

Reading 7-Bit DAC

The MAX8798 7-bit DAC is read by either pressing the

Read DAC button or by checking the DAC polling

checkbox. When checked, the software will continuously

read and display the DAC’s current setting.

Note that changing the MAIN voltage setting changes the

GON and GOFF charge-pump output voltages. The volt-

age range on GOFF is limited to -2ꢀV and the voltage

range of GON is limited to +3ꢀV. Setting the MAIN voltage

above +12V will require reconfiguring the charge pumps

to avoid exceeding +3ꢀV on GON and -2ꢀV on GOFF.

Programming EEPROM

The current DAC setting can be programmed into the

device’s internal EEPROM by entering an appropriate

DAC setting into the DAC edit box and pressing the

Program button. Pressing the Program button will also

load the current setting into the DAC. Each time the

device is powered on, the DAC is loaded with the set-

ting stored in the device’s EEPROM. Programming is

only possible when GON is greater than +16V.

In addition, output capacitors C21 and C22 are rated

for +16V. To set MAIN for greater than +16V, use high-

er voltage-rated capacitors. Refer to the Main Step-Up

Regulator, Output-Voltage Selection section in the

MAX8798 IC data sheet for instructions on selecting

resistors R1 and R2.

Detailed Description of Software

Simple SMBus Commands

There are two methods for communicating with the

MAX8798: through the MAX8798 EV kit software main

window (Figure 1), or through the interface window

available by selecting the Options | Interface menu

item from the menu bar. The Maxim command module

interface window (Figure 2) includes a 2-wire interface

tab that allows for execution of the SMBusSendByte(),

SMBusReceiveByte(), and SMBusQuick() commands.

See Table 3 for details regarding SMBus commands.

The MAX8798 device includes a calibrator that is used

for adjusting an LCD’s backplane voltage (VCOM) in

TFT-LCD displays. The VCOM voltage is adjusted by

controlling the amount of sink current drawn by the cali-

brator. This is accomplished by programming the

desired setting into the device’s 7-bit internal DAC. The

software also facilitates reading of the device and pro-

gramming of the device’s internal EEPROM. Refer to

the MAX8798 IC data sheet for further details.

Loading 7-Bit DAC Setting

The DAC setting corresponds to a certain sink-current

level, which in turn corresponds to a specific VCOM

voltage. With the MAX8798 EV kit software, the device’s

7-bit internal DAC is configured by entering an appro-

The Command byte combo box accepts numeric data

in binary, decimal, or hexadecimal. Hexadecimal num-

bers should be prefixed by $ or 0x. Binary numbers

must be exactly eight digits. See Figure 2 for an illustra-

tion of this tool.

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MAX8798 Evaluation Kit/Evaluation System

Evluate:MAX798

Figure 2. Command Module Interface Window

Table 3. SMBus Commands

CONTROL

SMBus COMMAND

FORMAT

Input the desired 7-bit DAC setting into the Command byte

combo box. The 7-bit DAC value should be stored in the upper 7

bits (b7-b1) of the byte, with the LSB = 1.

Load DAC

SMBusSendByte

Input the desired 7-bit DAC setting into the Command byte

combo box. The 7-bit DAC value should be stored in the upper 7

bits (b7-b1) of the byte, with the LSB = 0.

Load DAC/program EEPROM

SMBusSendByte

Receives 8 bits from the device. The upper 7 bits correspond to

the current DAC setting and the LSB = 0.

Read DAC

SMBusReceiveByte

SMBusQuick

Search for device address shown in the Target Device Address

combo box. The MAX8798 device address is 0x9E.

Device search

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MAX8798 Evaluation Kit/Evaluation System

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Figure 3. MAX8798 EV Kit Schematic

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MAX8798 Evaluation Kit/Evaluation System

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Figure 4. MAX8798 EV Kit Component Placement Guide—Component Side

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MAX8798 Evaluation Kit/Evaluation System

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Figure ꢀ. MAX8798 EV Kit PCB Layout—Component Side

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MAX8798 Evaluation Kit/Evaluation System

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Figure 6. MAX8798 EV Kit PCB Layout—Layer 2

10 ______________________________________________________________________________________

MAX8798 Evaluation Kit/Evaluation System

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Figure 7. MAX8798 EV Kit PCB Layout—Layer 3

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MAX8798 Evaluation Kit/Evaluation System

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Figure 8. MAX8798 EV Kit PCB Layout—Solder Side

12 ______________________________________________________________________________________

MAX8798 Evaluation Kit/Evaluation System

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Revision History

REVISION

NUMBER

REVISION

DATE

PAGES

CHANGED

DESCRIPTION

9/07

9/08

Initial release

Corrected part number for component L1.

—

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.

Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 13

is a registered trademark of Maxim Integrated Products, Inc.

MAX8798EVKIT [MAXIM]

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