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General Description

The MAX17094 includes a high-performance step-up

regulator, a 250mA low-dropout (LDO) linear regulator, a

high-speed operational amplifier, a digitally adjustable

VCOM calibration device with nonvolatile memory and

C interface, and seven integrated high-voltage level

shifters. The device is optimized for thin-film transistor

(TFT) liquid-crystal display (LCD) applications.

The step-up DC-DC converter is a current-mode regu-

lator that provides the regulated supply voltage for

panel source driver ICs. The current-mode architecture

provides fast-transient responses to pulsed loads typi-

cal of source driver loads. The high switching frequen-

cy, which is programmable to any frequency between

450kHz to 1.2MHz with a single resistor, allows the use

of ultra-small inductors and ceramic capacitors. The

step-up regulator’s soft-start time is controlled by an

internal 10ms digital timer that requires no external

components; or if desired, the soft-start time can be

adjusted by adding a single external capacitor.

The low-voltage LDO linear regulator can provide at

least 250mA. The output voltage is accurate within ±2%.

The high-voltage, level-shifting scan driver is designed

to work with panels that incorporate row drivers on the

panel glass. Its seven outputs swing from +30V to -10V

and can swiftly drive capacitive loads.

The high-performance op amp is designed to drive the

LCD backplane and features 20MHz bandwidth, 45V/µs

slew rate, and 150mA output currents.

The programmable VCOM calibrator is externally

attached to the VCOM amplifier’s resistive voltage-

divider and sinks a programmable current to adjust the

VCOM voltage level. An internal 7-bit digital-to-analog

converter (DAC) controls the sink current. The DAC is

ratiometric relative to AVDD and is guaranteed monoto-

nic over all operating conditions. The calibrator

includes a nonvolatile memory device (IVR) to store the

desired VCOM voltage level. The 2-wire I

C interface

simplifies production equipment.

The MAX17094 is available in a 48-pin, 6mm x 6mm

TQFN package with a maximum thickness of 0.8mm for

thin LCD panels.

Applications

Notebook Computer Displays

Features

o 1.8V to 5.5V IN Supply Voltage Range

o 450kHz to 1.2MHz Adjustable Frequency Current-

Mode Step-Up Regulator

Fast-Transient Response

Integrated 14V, 2.5A, 150mΩ MOSFET

High Efficiency (> 85%)

o Low-Dropout Linear Regulator

High-Accuracy Output Voltage (2.0%)

Internal Digital Soft-Start

o High-Performance Operational Amplifier

200mA Output Short-Circuit Current

45V/µs Slew Rate

20MHz, -3dB Bandwidth

Rail-to-Rail Inputs and Outputs

o High-Voltage Drivers

+30V to -10V Outputs

o I

C Programmable VCOM Calibrator

7-Bit Adjustable Current-Sink Output

Nonvolatile IVR Memory

o Thermal-Overload Protection

MAX17094

Internal-Switch Boost Regulator with Integrated

7-Channel Driver, VCOM Calibrator, Op Amp, and LDO

________________________________________________________________

Maxim Integrated Products

TOP VIEW

MAX17094

TQFN

YDCHG

345

*EP

*EP = EXPOSED PAD.

678910

AGND

COMP

SENSE

FREQ

PGND

SDA

SCL

ADDR1

ADDR0

GND

FBL

LOUT

LIN

34 33 32 31 30 29 28 27

GOFF

GND

GON2

GON1

GND

SET

BGND

VCOM

NEG

POS

OUT

AVDD

Pin Configuration

Ordering Information

19-4348; Rev 0; 10/08

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

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

EVALUATION KIT

AVAILABLE

Denotes a lead(Pb)-free/RoHS-compliant package.

EP = Exposed pad.

PART TEMP RANGE PIN-PACKAGE

MAX17094ETM+ -40°C to +85°C 48 TQFN-EP*

Summary of content (26 pages)

PAGE 1
9-4348; Rev 0; 10/08 KIT ATION EVALU E L B A AVAIL Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO PIN-PACKAGE GOFF GND GON2 GON1 GND SET BGND VCOM NEG OUT TOP VIEW POS Pin Configuration 36 35 34 33 32 31 30 29 28 27 26 25 FB 37 24 Y8 PGND 38 23 Y7 PGND 39 22 Y6 LX 40 21 Y5 LX 41 20 Y4 42 19 Y3 FREQ MAX17094 EN 43 18 Y2 IN 44 17 YDCHG SENSE 45 16 SS COMP 46 15 A2 AGND 47 14 A3 VL 48 13 A4 *E
PAGE 2
MAX17094 Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO ABSOLUTE MAXIMUM RATINGS IN, LIN, LOUT, EN, VL, A2–A8, SCL, SDA, ADDR0, ADDR1.. ............................-0.3V to +7.5V COMP, FB, SENSE, SS to AGND ............…-0.3V to (VVL + 0.3V) FBL to AGND.............................................-0.3V to (VLIN + 0.3V) FREQ, SET to GND .....................................-0.3V to (VVL + 0.3V) LX to PGND ...................................................
PAGE 3
Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO (VIN = VLIN = VEN = +3.3V, circuit of Figure 2, VMAIN = 8V, VGON1 = VGON2 = 21V, VGOFF = -6.5V, TA = 0°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX RFREQ = 80k 1000 1200 1500 RFREQ = 30k 382 450 518 RFREQ = unconnected 570 600 690 UNITS STEP-UP DC-DC CONVERTER Switching Frequency f (MHz) = 0.
PAGE 4
MAX17094 Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO ELECTRICAL CHARACTERISTICS (continued) (VIN = VLIN = VEN = +3.3V, circuit of Figure 2, VMAIN = 8V, VGON1 = VGON2 = 21V, VGOFF = -6.5V, TA = 0°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX UNITS 14 V 15 15.
PAGE 5
Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO (VIN = VLIN = VEN = +3.3V, circuit of Figure 2, VMAIN = 8V, VGON1 = VGON2 = 21V, VGOFF = -6.5V, TA = 0°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.) PARAMETER CONDITIONS SET Full-Scale Error MIN TYP -4 SET Current SET External Resistance UNITS +5 LSB 120 μA To GND, VAVDD = 14V 8.5 170 To GND, VAVDD = 6V 2.
PAGE 6
MAX17094 Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO ELECTRICAL CHARACTERISTICS (VIN = VLIN = VEN = +3.3V, circuit of Figure 2, VMAIN = 8V, VGON1 = VGON2 = 21V, VGOFF = -6.5V. TA = -40°C to +85°C, unless otherwise noted.) (Note 3) PARAMETER CONDITIONS MIN TYP MAX UNITS 5.5 V GENERAL IN Input-Voltage Range 1.8 IN Shutdown Current EN = 0, VL > 2.4V 100 μA IN Quiescent VIN = 3V, VFB = 1.
PAGE 7
Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO (VIN = VLIN = VEN = +3.3V, circuit of Figure 2, VMAIN = 8V, VGON1 = VGON2 = 21V, VGOFF = -6.5V. TA = -40°C to +85°C, unless otherwise noted.
PAGE 8
MAX17094 Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO ELECTRICAL CHARACTERISTICS (continued) (VIN = VLIN = VEN = +3.3V, circuit of Figure 2, VMAIN = 8V, VGON1 = VGON2 = 21V, VGOFF = -6.5V. TA = -40°C to +85°C, unless otherwise noted.) (Note 3) PARAMETER CONDITIONS MIN TYP MAX UNITS INPUT-VOLTAGE DETECTOR SENSE Voltage Range SENSE Threshold Voltage Falling edge, 10mV (typ) hysteresis 1.200 VVL V 1.270 V 10.
PAGE 9
Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO (VIN = VLIN = VEN = +3.3V, circuit of Figure 2, VMAIN = 8V, VGON1 = VGON2 = 21V, VGOFF = -6.5V. TA = -40°C to +85°C, unless otherwise noted.) (Note 3) Note 1: Guaranteed by design, not production tested. Note 2: The maximum amount capacitance allowed on the SDA bus lines. Note 3: TA = -40°C specifications are guaranteed by design, not production tested.
PAGE 10
Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) 25 0.2A LOAD 15 10 30 VIN = 3.3V 25 20 15 5 0 0 2.7 3.8 4.9 6.0 -40 -15 10 35 60 NO LOAD ON VMAIN 3 85 6 9 SUPPLY VOLTAGE (V) AVDD CURRENT vs. TEMPERATURE STEP-UP CONVERTER SWITCHING FREQUENCY vs. RFREQ STEP-UP CONVERTER SWITCHING FREQUENCY vs. INPUT VOLTAGE VAVDD = 14V 5.0 4.8 VAVDD = 8V 4.6 VIN = 3.3V NO LOAD ON VMAIN 4.2 1200 1000 800 600 400 VIN = 3.3V VMAIN = 8V IMAIN = 350mA LOAD 200 4.
PAGE 11
Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO STEP-UP REGULATOR PULSED LOAD-TRANSIENT RESPONSE (20mA TO 1A) POWER-UP SEQUENCE OF ALL SUPPLY OUTPUTS MAX17094 toc12 MAX17094 toc13 0 VLX 10V/div 0 IL1 1A/div 0 0 0 0 0 VMAIN (AC-COUPLED) 500mV/div 0 VIN 5V/div VL 5V/div VMAIN 5V/div VCOM 5V/div VLOUT 5V/div VGON 20V/div 0 IMAIN 1A/div 0 VGOFF 20V/div 0 10μs/div 1ms/div RCOMP = 40.2kΩ CCOMP = 1000pF LDO OUTPUT REGULATION vs. LOAD CURRENT 0.
PAGE 12
MAX17094 Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.
PAGE 13
Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO PIN NAME 1 LIN 2 LOUT 3 FBL Linear Regulator Feedback Pin. Connect external resistor-divider tap here and minimize trace area. Set VLOGIC according to: VLOGIC = 0.618V x (1 + R7/R8) (Figure 2).
PAGE 14
Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO MAX17094 Pin Description (continued) PIN NAME FUNCTION 43 EN Enable. Pull EN low to turn off the DC-DC converter and the op amp. The high-voltage scan drivers and LDO remain active if sufficient voltage is available for operation. 44 IN Supply. Bypass to AGND with a minimum 0.1μF ceramic capacitor. 45 SENSE Input-Voltage Threshold Detector. Connect this pin to VIN through a resistor-divider.
PAGE 15
Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO 0.1μF D4 0.1μF VP 21V, 50mA D3 0.1μF MAX17094 D2 VN -6.5V, 50mA 0.1μF 0.1μF L1 4.1μH VIN 3.3V 15pF D1 RENA 80.6kΩ VLOGIC 2.5V, 250mA LIN FREQ EN IN VMAIN 8V, 300mA C4 10μF C3 1μF C2 1μF 0.1μF C5 4.7μF LX C6 4.7μF PGND LOUT R1 200kΩ C1 R7 4.7μF 63.4kΩ FB FBL RCOMP 40.2kΩ COMP R8 21kΩ SS GND CSS 0.1μF CCOMP 1000pF R2 36.5kΩ AGND VL 10kΩ 0.
PAGE 16
MAX17094 Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO VP VN VMAIN VIN IN LIN VLOGIC LOUT FREQ 250mA LINEAR REGULATOR EN LX PGND STEP-UP CONVERTER FBL FB COMP SS GND BOOTSRAP LINEAR REGULATOR VL SDA SCL ADDR0 ADDR1 2 I C BUS I2C 7 CONTROL INTERFACE AVDD DATA REGISTER 00H NEG OP WR 1 GON2 VP AGND 19R 7 00 CONTROL RSB REGISTER 02H IVR VCOM TO VCOM BACKPLANE BGND POS R OUT DAC 7F GON1 SET SENSE VIN REF COMP FROM TCON
PAGE 17
Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO The MAX17094 includes a high-performance step-up regulator, a 250mA LDO linear regulator, a high-speed operational amplifier, a digitally adjustable VCOM calibration device with nonvolatile memory and I2C interface, and a high-voltage, level-shifting scan driver optimized for active-matrix TFT LCDs.
PAGE 18
MAX17094 Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO Soft-Start The soft-start feature effectively limits the inrush current during startup by linearly ramping up the step-up converter’s peak switch current limit. The soft-start period terminates when either the output voltage reaches regulation or the full current limit has been reached.
PAGE 19
Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO Thermal-Overload Protection The thermal-overload protection prevents excessive power dissipation from overheating the device. When the junction temperature exceeds TJ = +160°C, a thermal sensor immediately activates the fault protection, which shuts down the step-up regulator, LDO, and the operational amplifiers, allowing the device to cool down.
PAGE 20
MAX17094 Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO The maximum output current, input voltage, output voltage, and switching frequency determine the inductor value. Very high inductance values minimize the current ripple and therefore reduce the peak current, which decreases core losses in the inductor and I2R losses in the entire power path.
PAGE 21
Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO IIN(DC,MAX) = 0.38 A × 8V ≈ 1.24 A 3V × 0.82 The ripple current and the peak current at that input voltage are: 3V × ( 8V - 3V ) IRIPPLE = ≈ 0.381A 4.1μH × 8V × 1.2MHz 0.381A = 1.43 A IPEAK = 1.24 A + 2 Setting the Switching Frequency To set the switching frequency, connect a resistor from FREQ to AGND. Calculate the resistor value in kΩ from the following equation: f(MHZ) = 0.
PAGE 22
MAX17094 Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO Input-Voltage Detector The falling-edge input-voltage threshold used by the voltage detector to drive YDCHG to VGON1 during powerdown is adjusted by connecting a resistive voltagedivider from VIN to AGND with the center tap connected to SENSE (see Figure 2). Select R6 in the 10kΩ range. Calculate R5 with the following equation: ⎛ VIN(THRESHOLD) ⎞ R5 = R6 × ⎜ - 1⎟ 1.
PAGE 23
Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO PDLDO = ILOUT × ( VLIN - VLOUT ) Scan Driver Outputs The power dissipated by the scan driver outputs (Y2–Y8) depends on the scan frequency, the voltage difference between the power rails across each driver, and the capacitive load driven by each output.
PAGE 24
MAX17094 Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO The MAX17094 does not generate an acknowledge while an internal programming cycle is in progress. Once the internally timed write cycle has started and the IVR inputs are disabled, acknowledge polling can be initiated. This involves sending a START condition followed by the device address byte.
PAGE 25
Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO to zeros. The ACR comprises volatile memory, which is preset to 00h during power-up. Figure 10 shows the ACR byte. Access Control Register (ACR) 02h The register select bit (RSB) is the most significant bit of the byte stored in the ACR and is used to select whether WR or IVR is accessed during read and write cycles involving the data register.
PAGE 26
MAX17094 Internal-Switch Boost Regulator with Integrated 7-Channel Driver, VCOM Calibrator, Op Amp, and LDO PCB Layout and Grounding capacitor ground connection, and the device’s exposed backside pad. Create a ground plane (BGND) to carry operational amplifier return current with the AVDO bypass capacitor connected to this ground plane. Connect the AGND, BGND, and PGND islands by connecting the PGND and BGND pins directly to the exposed backside pad.