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General Description

The MAX1513/MAX1514 provide complete power-sup-

ply solutions for active-matrix thin-film transistor (TFT)

liquid-crystal displays (LCDs). Both devices include a

high-performance step-up regulator controller, three lin-

ear-regulator controllers, and an adjustable delay block

for startup sequencing. The MAX1513 includes an

additional linear-regulator controller and a high-perfor-

mance buffer amplifier. The MAX1513/MAX1514 can

operate from 2.7V to 5.5V input supplies and provide

overload protection with timer delay latch on all the reg-

ulated outputs.

The step-up regulator controller drives an external N-

channel MOSFET to generate the regulated supply volt-

age for the panel source-driver ICs. Its current-mode

control architecture provides fast transient response to

pulsed loads. The high switching frequency (up to

1.5MHz) allows the use of ultra-small inductors and

ceramic capacitors while achieving efficiencies over 85%

using lossless current sensing. The internal soft-start lim-

its the input surge current during startup.

The gate-on and gate-off linear-regulator controllers of

the MAX1513/MAX1514 provide regulated TFT gate-on

and gate-off supplies. The gate-on supply is activated

after an adjustable delay following the step-up regulator.

The logic linear-regulator controller can be used to cre-

ate a low-voltage logic supply. The gamma linear-regula-

tor controller of the MAX1513 can be used to generate a

gamma-correction reference supply or another general-

purpose supply rail. The MAX1513’s high-performance

buffer amplifier can drive the LCD backplane (VCOM)

or the gamma-correction divider string.

The MAX1513/MAX1514 are available in 4mm ✕ 4mm

20-pin thin QFN packages with a maximum thickness of

0.8mm, suitable for ultra-thin LCD panel design.

Applications

Notebook Computer Displays

LCD Monitors and TVs

Automotive Displays

Features

♦ 2.7V to 5.5V Input Supply Range

♦ Input-Supply Undervoltage Lockout

♦ Current-Mode Step-Up Controller

Fast Transient Response to Pulsed Load

High Efficiency

Lossless Current Sensing

430kHz/750kHz/1.5MHz Switching Frequency

♦ Linear-Regulator Controllers for V

GON

, V

GOFF

♦ Linear-Regulator Controller for Logic Supply

♦ High-Performance Buffer Amplifier (MAX1513 Only)

♦ Additional Linear-Regulator Controller

(MAX1513 Only)

♦ Power-Up Sequence and V

GON

Delay Control

♦ V

MAIN

, V

GON

, V

GOFF

, V

GAMMA

Shutdown Control

♦ Timer-Delay Fault Latch for All Outputs

♦ Thermal-Overload Protection

MAX1513/MAX1514

TFT-LCD Power-Supply Controllers

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

19-3047; Rev 0; 10/03

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

MAX1513ETP

-40°C to +85°C

20 Thin QFN 4mm x 4mm

MAX1514ETP

-40°C to +85°C

20 Thin QFN 4mm x 4mm

Pin Configuration appears at end of data sheet.

EVALUATION KIT

AVAILABLE

MAX1513

MAX1514

SDFR

GAMMA

DEL

DRVL

FBLV

LOGIC

MAIN

DRVG

FBG

SUPB

FBPB

OUTBTO VCOM

MAIN

GOFF

GON

CS+

CS-

GATE

GND

DRVP

FBP

DRVN

FBN

REF

Minimal Operating Circuit

Summary of content (28 pages)

PAGE 1
9-3047; Rev 0; 10/03 KIT ATION EVALU E L B A AVAIL TFT-LCD Power-Supply Controllers Features The MAX1513/MAX1514 provide complete power-supply solutions for active-matrix thin-film transistor (TFT) liquid-crystal displays (LCDs). Both devices include a high-performance step-up regulator controller, three linear-regulator controllers, and an adjustable delay block for startup sequencing. The MAX1513 includes an additional linear-regulator controller and a high-performance buffer amplifier.
PAGE 2
MAX1513/MAX1514 TFT-LCD Power-Supply Controllers ABSOLUTE MAXIMUM RATINGS FB, FBP, FBN, FBG, FBL, IN, CS+, CS-, SDFR to GND ...............................................-0.3V to +6V DEL, GATE, REF to GND .............................-0.3V to (VIN + 0.3V) SUPB to GND .........................................................-0.3V to +14V OUTB, FBPB to GND ..............................-0.3V to (VSUPB + 0.3V) DRVP, DRVG, DRVL to GND ..................................-0.3V to +30V DRVN to GND ...............
PAGE 3
TFT-LCD Power-Supply Controllers (Circuit of Figure 1, VIN = 3V, VSUPB = 10V, SDFR = IN, CREF = 0.22µF, TA = 0°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.) PARAMETER SYMBOL FBP Effective Load-Regulation Error (Transconductance) DRVP Off-Leakage Current VFBP = 1.1V, VDRVP = 10V MAX UNITS -1.5 -2 % 8 1 VFBP = 1.5V, VDRVP = 28V DEL Charge Current During startup, VDEL = 1.0V VTH(DEL) DEL Discharge Switch On-Resistance Soft-Start Period TYP IDRVP = 50µA, 2.7V < VIN < 5.
PAGE 4
MAX1513/MAX1514 TFT-LCD Power-Supply Controllers ELECTRICAL CHARACTERISTICS (continued) (Circuit of Figure 1, VIN = 3V, VSUPB = 10V, SDFR = IN, CREF = 0.22µF, TA = 0°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS GATE-OFF LINEAR-REGULATOR CONTROLLER (REG N) FBN Regulation Voltage IDRVN = 0.
PAGE 5
TFT-LCD Power-Supply Controllers (Circuit of Figure 1, VIN = 3V, VSUPB = 10V, SDFR = IN, CREF = 0.22µF, TA = -40°C to +85°C, unless otherwise noted.) (Note 1) PARAMETER IN Supply Range SYMBOL CONDITIONS MAX UNITS 2.7 5.5 V VIN rising 2.5 2.9 VIN falling 2.2 2.5 VIN IN Undervoltage-Lockout Threshold IN Quiescent Current VUVLO IIN REF Output Voltage 350mV typical hysteresis MIN VFB = VFBP = VFBL = VFBG = 1.5V, VFBN = 0 TYP V 1.25 mA V -2µA < IREF < 100µA, 2.7V < VIN < 5.5V 1.225 1.
PAGE 6
MAX1513/MAX1514 TFT-LCD Power-Supply Controllers ELECTRICAL CHARACTERISTICS (continued) (Circuit of Figure 1, VIN = 3V, VSUPB = 10V, SDFR = IN, CREF = 0.22µF, TA = -40°C to +85°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS LOGIC LINEAR-REGULATOR CONTROLLER (REG L) FBL Regulation Voltage VFBL IDRVL = 1mA 1.225 1.275 V FBL Input Bias Current VFBL = 1.5V -250 +250 nA FBL Effective Load-Regulation Error (Transconductance) VDRVL = 3V, IDRVL = 0.
PAGE 7
TFT-LCD Power-Supply Controllers OUTPUT VOLTAGE (V) 80 VIN = 2.7V VIN = 3.3V 70 60 VIN = 5V VIN = 15V fOSC = 1.5MHz 15.0 50 VMAIN 100mV AC-COUPLED 14.9 14.8 IMAIN 500mA/div 0.1A 14.7 IL 1A/div 0A 14.
PAGE 8
MAX1513/MAX1514 TFT-LCD Power-Supply Controllers Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = 5V, VMAIN = 15V, VGON = 25V, VGOFF = -10V, VLOGIC = 3.3V, VGAMMA = 14.7V, TA = +25°C, unless otherwise noted.
PAGE 9
TFT-LCD Power-Supply Controllers PIN NAME FUNCTION MAX1513 MAX1514 8 DRVN DRVN REG N Base Drive. Open drain of an internal P-channel MOSFET. Connect to the base of an external NPN linear-regulator pass transistor. 9 DRVL DRVL Logic Linear-Regulator (REG L) Base Drive. Open drain of an internal N-channel MOSFET. Connect to the base of an external PNP linear-regulator pass transistor. 10 FBL FBL REG L Feedback Input. FBL regulates to 1.25V (typ).
PAGE 10
MAX1513/MAX1514 TFT-LCD Power-Supply Controllers VIN 4.5V TO 5.5V L1 2.2µH C1 22µF 6.3V D1 OPEN R1 110kΩ 17 CS+ 470pF 19 CS- IN GATE 2 SDFR GND 7 DEL 0.47µF FB 16 N1 R2 10.0kΩ 15 20 1.5kΩ 680Ω 9 Q1 VLOGIC 3.3V/500mA R7 16.5kΩ 10µF 10 DRVL DRVG 0.1µF 11 Q4 R8 10.0kΩ FBG R9 107kΩ 12 0.47µF R10 10.0kΩ LX 0.1µF SUPB 5 3.6kΩ 0.1µF 0.1µF FBPB 8 Q2 VGOFF -10V/30mA VGAMMA 14.7V/30mA FBL MAX1513 D2 1MΩ 0.1µF 18 2.
PAGE 11
TFT-LCD Power-Supply Controllers VIN 4.5V TO 5.5V LX L1 2.2µH D1 C1 22µF 6.3V C2 10µF 16V 909Ω OPEN R11 10Ω R1 110kΩ 1MΩ 0.1µF 18 CS+ 17 470pF 19 CS- IN GATE C10 1µF 2 SDFR GND 7 DEL 0.47µF 2.2µF FB 16 N1 R2 10.0kΩ 15 20 LX 680Ω 0.1µF 9 Q1 VLOGIC 3.3V/500mA R7 16.5kΩ 10µF 10 6.8kΩ DRVL 0.1µF FBL DRVP R8 10.0kΩ MAX1514 LX 0.1µF D2 D3 FBP 14 13 Q3 R5 191kΩ R6 10.0kΩ VGON 25V/20mA 0.47µF 3.6kΩ 0.1µF 8 Q2 VGOFF -10V/30mA R3 102kΩ 0.47µF 6 DRVN FBN R4 10.
PAGE 12
MAX1513/MAX1514 TFT-LCD Power-Supply Controllers VIN CS+ MAX1513 MAX1514 SDFR CS- MAIN STEP-UP CONTROLLER WITH SOFT-START AND FAULT COMPARATOR DEL VMAIN GATE GND FB VIN DRVL REG L WITH SOFT-START AND FAULT COMPARATOR VLOGIC DRVP FBL REG P WITH SOFT-START AND FAULT COMPARATOR VGON FBP CONTROL BLOCK VMAIN DRVG VGAMMA FBG REG G WITH SOFT-START AND FAULT COMPARATOR DRVN REG N WITH SOFT-START AND FAULT COMPARATOR SUPB VGOFF FBN FBPB REFERENCE TO VCOM REF OUTB OP-AMP THERMAL SHUTDOW
PAGE 13
TFT-LCD Power-Supply Controllers Detailed Description The typical operating circuit of the MAX1513 (Figure 1) is a complete power-supply system for TFT LCDs. The circuit generates a +15V source-driver supply, +25V and -10V gate-driver supplies, a +3.3V logic supply for the timing controller, a 14.7V gamma-correction string supply and a VCOM buffer.
PAGE 14
MAX1513/MAX1514 TFT-LCD Power-Supply Controllers input PWM comparator, the flip-flop is reset and the MOSFET turns off. Since the inductor current is continuous, a transverse potential develops across the inductor that turns on the diode (D1). The voltage across the inductor then becomes the difference between the output voltage and the input voltage.
PAGE 15
TFT-LCD Power-Supply Controllers Gate-Off Linear-Regulator Controller The gate-off linear-regulator controller (REG N) is an analog gain block with an open-drain P-channel output. It drives an external NPN pass transistor with a 3.6kΩ base-to-emitter resistor (Figure 1). Its guaranteed basedrive source current is at least 2mA. The regulator, including Q2 in Figure 1, uses a 0.47µF ceramic output capacitor and is designed to deliver 30mA at -10V.
PAGE 16
MAX1513/MAX1514 TFT-LCD Power-Supply Controllers Gamma Linear-Regulator Controller (MAX1513 Only) The gamma linear-regulator controller REG G is an analog gain block with an open-drain N-channel output. It drives an external PNP pass transistor with a 1.5kΩ base-to-emitter resistor (Figure 1). Its guaranteed basedrive sink current is at least 5mA. The regulator, including Q4 in Figure 1, uses a 0.47µF ceramic output capacitor, and the controller is designed to deliver 40mA at 14.7V.
PAGE 17
TFT-LCD Power-Supply Controllers Fault Protection During steady-state operation, if the step-up regulator output or any of the linear-regulator outputs does not exceed its respective fault detection threshold, the MAX1513/MAX1514 activate an internal fault timer. If any condition or the combination of conditions indicates a continuous fault for the fault-timer duration (43.6ms typ), the MAX1513/MAX1514 set the fault latch, shutting down all the outputs except the reference.
PAGE 18
MAX1513/MAX1514 TFT-LCD Power-Supply Controllers taken from an appropriate curve in the Typical Operating Characteristics, and an estimate of LIR based on the above paragraphs: 2 ⎛ V ⎞ ⎛ VMAIN - VIN ⎞ ⎛ ηTYP ⎞ L = ⎜ IN ⎟ ⎜ ⎟ ⎟⎜ ⎝ VMAIN ⎠ ⎝ IMAIN(EFF) × fOSC ⎠ ⎝ LIR ⎠ Choose an available inductor value from an appropriate inductor family.
PAGE 19
TFT-LCD Power-Supply Controllers SF = 2.2µH = 91.7µs 24mΩ Select CS = 0.1µF and calculate RS: 100mV VSENSE 91.7µs = 917Ω 0.1µF RS = Assuming ∆T is 40°C and TC is 0.5%, the worst-case high sense voltage over temperature is: Calculate RS1 and RS2: VSENSE = 2.6A × 30mΩ (1 + 0.005 × 40°C) = 93.6mV RS SF R × SF RS2 = S1 1 - SF RS1 = 6) If VSENSE is less than 80mV, the current-feedback signal is low relative to the current-limit threshold.
PAGE 20
MAX1513/MAX1514 TFT-LCD Power-Supply Controllers Select CS = 0.1µF, RS is: L VMAIN VIN RS = RS3 CS 220µs = 2200Ω 0.1µF Assuming ∆T is 40°C and TC is 0.5%, the worst-case high sense voltage over temperature is: RS4 CS+ VSENSE = 2.6A × 14mΩ (1 + 0.005 × 40°C) = 44mV CSGATE MAX1513 MAX1514 Because VSENSE would be much less than 80mV, the circuit in Figure 10 can be used to improve the currentlimit accuracy. Calculate RS3 and RS4: GND FB RS3 = Figure 10.
PAGE 21
TFT-LCD Power-Supply Controllers RESR(MAX) ≤ VRIPPLE(MAX) 2 × IPEAK ⎛ V - VIN 2 × IMAIN COUT(MIN) ≥ × ⎜ MAIN VRIPPLE(MAX) ⎝ VMAIN × fOSC where VRIPPLE(MAX) is the total peak-to-peak output ripple. Since the peak inductor current calculated in the Inductor Selection section is 2.6A, the maximum ESR of the output capacitor should be less than 29mΩ. On the other hand, only 3.1µF capacitance is needed to meet the capacitive ripple requirement based on the calculation.
PAGE 22
MAX1513/MAX1514 TFT-LCD Power-Supply Controllers The DC loop gain (ADC) is approximately: R2 1- D VMAIN ADC = × × R1 + R2 0.554 × RCS IMAIN(EFF) where R1 and R2 are the feedback-divider resistors (Figure 1), D is the duty cycle, IMAIN(EFF) is the effective maximum output current as described in the Inductor Selection section, 0.
PAGE 23
TFT-LCD Power-Supply Controllers 1 R1 × R2 ⎞ ⎛ 2π × ⎜ R4 + ⎟ × C2 ⎝ R1 + R2 ⎠ 1 fZ _ LAG = 2π × R4 × C2 fP _ LAG = At high frequencies, R4 is effectively in parallel with R2, increasing the divider attenuation ratio. If R4 is very large, the attenuation ratio remains unchanged and as R4 approaches zero, the attenuation ratio approaches infinity. A typical value for R4 is greater than 0.1 times R2. If high-value divider-resistors are used, choose R4 < 1.5kΩ for FB noise immunity.
PAGE 24
POSITIVE CHARGE-PUMP OUTPUT VOLTAGE vs. VMAIN NEGATIVE CHARGE-PUMP OUTPUT VOLTAGE vs. VMAIN -0 60 VD = 0.3V TO 1V 3-STAGE CHARGE-PUMP 1-STAGE CHARGE-PUMP -5 50 -10 -15 G_OFF (V) 40 G_ON (V) MAX1513/MAX1514 TFT-LCD Power-Supply Controllers 2-STAGE CHARGE-PUMP 30 -20 2-STAGE CHARGE-PUMP -25 -30 20 3-STAGE CHARGE-PUMP -35 10 -40 1-STAGE CHARGE-PUMP VD = 0.3V TO 1V -45 0 2 4 6 8 10 12 14 2 4 6 8 10 12 14 VMAIN (V) VMAIN (V) Figure 13. Positive Charge-Pump Output Voltage vs.
PAGE 25
TFT-LCD Power-Supply Controllers COUT _ CP ≥ ILOAD _ CP 2fOSCVRIPPLE _ CP where COUT_CP is the output capacitor of the charge pump, I LOAD_CP is the load current of the charge pump, and VRIPPLE_CP is the peak-to-peak value of the output ripple. The charge-pump output capacitor is typically also the input capacitor for a linear regulator. Often, its value must be increased to maintain the linear regulator’s stability.
PAGE 26
MAX1513/MAX1514 TFT-LCD Power-Supply Controllers ⎡ ⎛I ⎛ 4⎞ × hFE ⎞ ⎤ A V _ LR ≈ ⎜ ⎟ × ⎢1 + ⎜ BIAS ⎟ ⎥ × VREF ⎝ VT ⎠ ⎢⎣ ⎝ ILOAD _ LR ⎠ ⎥⎦ where CIN = gm is the transconductance of the pass transistor, and fT is the transition frequency. Both parameters can be found in the transistor’s data sheet. Because RBE is much greater than RIN, the above equation can be simplified: where VT is 26mV at room temperature and IBIAS is the current through the base-to-emitter resistor (RBE).
PAGE 27
TFT-LCD Power-Supply Controllers 1) Minimize the area of high-current loops. The highcurrent input loop goes from the positive terminals of the input capacitors to the inductor, to the power MOSFET, and to the negative terminals of the input capacitors. The high-current output loop is from the positive terminals of the input capacitors to the inductor, to the output diode, and to the positive terminals of the output capacitors, reconnecting between the output-capacitor and input-capacitor ground terminals.
PAGE 28
Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) 24L QFN THIN.EPS MAX1513/MAX1514 TFT-LCD Power-Supply Controllers PACKAGE OUTLINE 12,16,20,24L QFN THIN, 4x4x0.8 mm 21-0139 B 1 2 PACKAGE OUTLINE 12,16,20,24L QFN THIN, 4x4x0.