MAX1579ETG+ ,Complete Bias and White LED Power Supplies for Small TFT Displaysfeatures a tem-♦ 1µA Shutdown Currentperature derating function to avoid overdriving the♦ Tiny 4mm ..
MAX1579ETG+T ,Complete Bias and White LED Power Supplies for Small TFT DisplaysApplicationsPDAs, Palmtops LCD Displays withC1N 19 12 GNDWhite LED BacklightSmart Phones20 11 ONBIA ..
MAX157ACUA ,+2.7V, Low-Power, 2-Channel, 108ksps, Serial 10-Bit ADCs in 8-Pin ?MAXApplicationsMAX157ACUA 0°C to +70°C 8 µMAX ±0.5Battery-Powered Systems InstrumentationMAX157BCUA 0° ..
MAX157ACUA+ ,+2.7V, Low-Power, 2-Channel, 108ksps, Serial 10-Bit ADCs in 8-Pin µMAXELECTRICAL CHARACTERISTICS(V = +2.7V to +5.25V, V = 2.5V, 0.1μF capacitor at REF, f = 2.17MHz, 16 c ..
MAX157BCPA+ ,+2.7V, Low-Power, 2-Channel, 108ksps, Serial 10-Bit ADCs in 8-Pin µMAXFeaturesThe MAX157/MAX159 low-power, 10-bit analog-to-digi-♦ Single-Supply Operation (+2.7V to +5.2 ..
MAX157BCUA ,+2.7V, Low-Power, 2-Channel, 108ksps, Serial 10-Bit ADCs in 8-Pin ?MAXFeaturesThe MAX157/MAX159 low-power, 10-bit analog-to-digi-' Single-Supply Operation (+2.7V to +5.2 ..
MAX4242ESA ,Single/Dual/Quad / !.8V/10A / SOT23 / Beyond-the-Rails Op AmpsFeaturesThe MAX4240–MAX4244 family of micropower op amps' Ultra-Low-Voltage Operation:operate from ..
MAX4242ESA+ ,Single/Dual/Quad, +1.8V/10µA, SOT23, Beyond-the-Rails Op Ampsapplications.PART TEMP RANGEPACKAGE MARKThe MAX4240 is offered in a space-saving 5-pinSOT23 package ..
MAX4242ESA+T ,Single/Dual/Quad, +1.8V/10µA, SOT23, Beyond-the-Rails Op AmpsELECTRICAL CHARACTERISTICS (V = +1.8V to +5.5V, V = 0, V = 0, V = V / 2, R = 100kΩ tied to V / 2, S ..
MAX4242EUA ,Single/Dual/Quad / !.8V/10A / SOT23 / Beyond-the-Rails Op Ampsapplications.PIN- SOT PART TEMP. RANGEThe MAX4240 is offered in a space-saving 5-pin SOT23 PACKAGE ..
MAX4242EUA ,Single/Dual/Quad / !.8V/10A / SOT23 / Beyond-the-Rails Op AmpsGeneral Description ________
MAX4242EUA ,Single/Dual/Quad / !.8V/10A / SOT23 / Beyond-the-Rails Op AmpsGeneral Description ________
MAX1578ETG+-MAX1578ETG+T-MAX1579ETG+-MAX1579ETG+T
Complete Bias and White LED Power Supplies for Small TFT Displays
General DescriptionThe MAX1578/MAX1579 provide four regulated outputs
to meet all the voltage requirements for small active-
matrix TFT-LCD displays in handheld devices where
minimum external components and high efficiency are
required. Each device consists of three advanced
charge pumps for LCD bias power and a step-up con-
verter for driving up to 8 series white LEDs for back-
lighting. The input voltage range is from 2.7V to 5.5V.
The charge pumps provide fixed +5V, +15V, and -10V
for the LCD bias circuits. No external diodes are need-
ed. A high-efficiency, fractional (1.5x/2x) charge pump
followed by a low-dropout linear regulator provides +5V
to power the source driver. Automatic mode changing
achieves the highest conversion efficiency. Two multi-
stage, high-voltage charge pumps generate +15V and
-10V to provide VONand VOFF, respectively. Utilizing a
unique clocking scheme and internal drivers, these
charge pumps eliminate parasitic charge-current glitch-
es and reduce maximum input current, resulting in low
electromagnetic emissions. The outputs are sequenced
during startup and shutdown. In shutdown, the outputs
are discharged to zero.
The high-efficiency inductor step-up converter drives
up to 8 white LEDs in series with a constant current to
provide backlighting. The series connection allows the
LED currents to be identical for uniform brightness and
minimizes the number of traces to the LEDs. The
MAX1578 regulates constant LED current over the
entire temperature range. The MAX1579 features a tem-
perature derating function to avoid overdriving the
white LEDs during high ambient temperatures, enabling
higher drive current below +42°C.
The MAX1578/MAX1579 are available in space-saving
24-lead 4mm x 4mm thin QFN packages.
Applications
FeaturesFour Regulators in One PackageBias Power Using Charge Pumps
+5V at 25mA for Source Driver
+15V at 100µA for VON
-10V at 100µA for VOFF
No External Diodes Required
Output Sequencing
POS, NEG, and MAIN Are Autodischarged
During ShutdownLED Backlight Power Using Boost Converter
Series LED Connection for Uniform Illumination
Supports Up to 8 LEDs at 25mA (max)
900mW (max) Power
PWM or Analog Dimming Control
Overvoltage Protection
Low Input/Output Ripple
Soft-Start with Zero Inrush Current
Fast 1MHz PWM Operation for Small
Component Size
Temperature Derating Function (MAX1579)High Efficiency
Bias: 83% (5.0V at 25mA, 15V/-10V at 100µA)
LED: 84% (6 LEDs at 20mA)Uses Only Ceramic Capacitors and Only One
InductorIndependent Enable Inputs for LED and Bias
PowerThermal-Shutdown Protection1µA Shutdown CurrentTiny 4mm x 4mm Thin QFN Package
MAX1578/MAX1579
Complete Bias and White LED Power Supplies
for Small TFT Displays19-3359; Rev 1; 8/05
Ordering Information
EVALUATION KIT
AVAILABLE
PARTTEMP RANGEPIN-PACKAGE
MAX1578ETG-40°C to +85°C24 Thin QFN 4mm x 4mm
(T2444-4)
MAX1578ETG+-40°C to +85°C24 Thin QFN 4mm x 4mm
(T2444-4)
MAX1578/MAX1579
See Figure 3 for Typical Application Circuit.ONBIAS
CD2
GND
NEG
PMPB
CD1CTRLPGNDOUTCOMPCS
CU1CU3
MAIN
CU2
PMP
POS234561716151413
MAX1578
MAX1579
THIN QFN4mm x 4mmC2N
C2P
C1N
VDD
C1P
Pin Configuration
Ordering Information continued at end of data sheet.PDAs, Palmtops
Smart Phones
Internet Appliances
LCD Displays with
White LED Backlight
+ Denotes lead-free package.
MAX1578/MAX1579
Complete Bias and White LED Power Supplies
for Small TFT Displays
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(Circuit of Figure 3, VIN= 3V, CTRL = ONBIAS = IN, TA= -40°C to +85°C, typical values are at TA= +25°C, unless otherwise noted. Note 1)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
IN, CS, C1N, C2N, MAIN, ONBIAS, VDDto GND.....-0.3V to +6V
CTRL to GND..................-0.3V to the lesser of +6V or (VIN+ 2V)
LX, OUT to GND.....................................................-0.3V to +37V
COMP to GND.............................................-0.3V to (VIN+ 0.3V)
CU1 to MAIN............................................................-0.3V to +6V
CU2 to CU1..............................................................-0.3V to +6V
CU3 to CU2..............................................................-0.3V to +6V
CU3 to POS............................................................-0.3V to +18V
CU3 to GND...........................................................-0.3V to +18V
POS to GND...........................................................-0.3V to +18V
CD1 to MAIN..........................................................+0.3V to -12V
CD1 to GND.............................................................+0.3V to -6V
CD2 to CD1..............................................................+0.3V to -6V
NEG to CD2..............................................................+0.3V to -6V
NEG, CD2 to GND..................................................+0.3V to -12V
C1P, C2P to GND...........................................-0.3V to (VIN+ 6V)
PMP, PMPB to GND................................-0.3V to (VMAIN+ 0.3V)
GND to PGND.......................................................-0.3V to +0.3V
ILX...................................................................................1.0ARMS
Continuous Power Dissipation (TA= +70°C)
24-Pin 4mm x 4mm Thin QFN
(derate 20.8mW/°C above +70°C).............................1667mW
Short-Circuit Duration (MAIN, POS, NEG)..................Continuous
Operating Temperature Range...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s)................................+300°C
PARAMETERCONDITIONSMINTYPMAXUNITSIN Operating Supply Range2.75.5V
IN Undervoltage-Lockout (UVLO)
ThresholdRising edge, 30mV hysteresis2.12.352.6V
IN Quiescent CurrentSwitching35mA
TA = +25°C0.41IN Shutdown CurrentVCTRL = VONBIAS = 0VTA = +85°C1µA
Thermal ShutdownRising temperature, 20°C hysteresis (typ)+160°C
MAIN CHARGE PUMP WITH LINEAR REGULATORMain Pump EfficiencyILOAD = 25mA, VIN = 3.9V83%
VIN ≥ 3.8V in 1.5x mode920VDD Charge-Pump Open-Loop
Output ImpedanceVIN ≥ 3.0V in 2.0x mode7.520Ω
Operating Frequency200250300kHz
VDD Output VoltageCharge-pump pause threshold5.25.55.7VIN Fal l i ng S w i tchover to 2.0x M od e3.753.853.95VIN Ri si ng S w i tchover to 1.5x M od e3.83.94.0V
Quiescent Current
(Charge Pumps Only)VCTRL = 0V, ONBIAS = IN0.871.30mA
VMAIN Regulation Voltage0.1mA < ILOAD < 25mA4.95.05.1V
Discharge Switch Resistance
at VMAINVONBIAS = 0V13kΩ
POS, NEG CHARGE PUMPSOperating Frequency12.015.619.5kHz
Duty Cycle50%
POS Pump EfficiencyILOAD = 100µA97%
POS Output VoltageILOAD = 0 to 100µA13.914.715.3VOS D i schar g e S w i tch Resi stanceVONBIAS = 0V36kΩ
NEG Pump EfficiencyILOAD = -100µA97%
MAX1578/MAX1579
Complete Bias and White LED Power Supplies
for Small TFT Displays
PARAMETERCONDITIONSMINTYPMAXUNITSNEG Output VoltageILOAD = 0 to -100µA-10.2-9.8-9.3VE G D i schar g e S w i tch Resi stanceVONBIAS = 0V1.53kΩ
LOGIC INPUT (ONBIAS)Logic Input Low Voltage0.72V
Logic Input High Voltage1.6V
TA = +25°C0.011Input CurrentTA = +85°C1µA
LED BACKLIGHTINGEfficiencyLOAD = 6 LEDs in series at 20mA84%
OUT Voltage Range(Note 2)(VIN -
VD1)32V
Overvoltage-Lockout (OVLO)
ThresholdVOUT rising, 2V hysteresis323436V
VOUT = 32V, VCTRL > 0.24V102032
TA = +25°C0.011OUT Input Bias CurrentVOUT = VIN, VCTRL = 0TA = +85°C0.1
ERROR AMPLIFIERTA = +25°C0.2950.3000.305CTRL to CS RegulationVCTRL = 1.5V, VIN = 2.7V to
5.5VTA = -40°C to +85°C0.2920.3000.308V
TA = +25°C0.011CS Input Bias CurrentVCS = VCTRL / 5TA = +85°C0.03µA
MAX1578250500780
TA = +25°C250500780CTRL Input ResistanceVCTRL < 1.0VMAX1579TA = +85°C185
CTRL Dual Mode Threshold5mV hysteresis100170240mV
CTRL Shutdown Delay(Note 3)6.58.210.5ms
CS to COMP TransconductanceVCOMP = 1.0V326090µS
CS Regulation Derating Function
Start TemperatureVCTRL = 3V, MAX1579 only+42°C
CS Regulation Derating Function
SlopeVCTRL = 3V, TA = +65°C, MAX1579 only-6mV/°C
MAX1578, VCTRL = 3V310327345CS Maximum Brightness Clamp
VoltageMAX1579, VCTRL = 3V, TA = +25°C322340358mV
MAX15781.635CS Maximum Brightness Voltage
at CTRLMAX15791.70V
OSCILLATOROperating FrequencyfBOOST0.81.01.2MHz
PWM mode12Minimum Duty CyclePulse skipping0%
Maximum Duty CycleCTRL = IN, CS = GND9295%
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 3, VIN= 3V, CTRL = ONBIAS = IN, TA= -40°C to +85°C, typical values are at TA= +25°C, unless otherwise noted. Note 1)
MAX1578/MAX1579
Complete Bias and White LED Power Supplies
for Small TFT Displays
Note 1:All devices are 100% production tested at TA= +25°C. Limits over the operating temperature range are guaranteed by design.
Note 2:VD1is the forward-voltage drop of diode D1 in Figure 3.
Note 3:Time from CTRL going below the Dual-Mode threshold to IC shutdown.
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 3, VIN= 3V, CTRL = ONBIAS = IN, TA= -40°C to +85°C, typical values are at TA= +25°C, unless otherwise noted. Note 1)
PARAMETERCONDITIONSMINTYPMAXUNITS
N-CHANNEL SWITCHLX On-ResistanceILX = 190mA0.821.5Ω
TA = +25°C0.015LX Leakage CurrentVLX = 28V, CTRL = GNDTA = +85°C1µA
LX Current LimitDuty cycle = 90%500700900mA
Typical Operating Characteristics(Circuit of Figure 3, VIN= 3.6V, ILED= 20mA, 4 LEDs, CTRL = IN, TA= +25°C, unless otherwise noted.)510152025
LED EFFICIENCY vs. ILEDMAX1578toc01
LED CURRENT (mA)
EFFICIENCY (%)
2 LEDs
4 LEDs6 LEDs
8 LEDs
LED EFFICIENCY vs. VIN
MAX1578toc02
INPUT VOLTAGE (V)
EFFICIENCY (%)ILED = 2mA
ILED = 10mA
ILED = 20mA
LED CURRENT vs. TEMPERATURE
MAX1578toc03
TEMPERATURE (°C)
ILED
(mA)-153560
MAX1579
RCS = 13Ω
MAX1578
RCS = 22Ω
LED CURRENT vs. VCTRL
MAX1578toc04
CTRL VOLTAGE (V)
ILED
(mA)
Typical Operating Characteristics (continued)(Circuit of Figure 3, VIN= 3.6V, ILED= 20mA, 4 LEDs, CTRL = IN, TA= +25°C, unless otherwise noted.)
MAX1578/MAX1579
Complete Bias and White LED Power Supplies
for Small TFT Displays
PWM-DIMMING WAVEFORMSMAX1578toc08
VCTRL
IIN
VOUT
AC-COUPLED
VIN
AC-COUPLED
2V/div
50mV/div
20mA/div
20mV/div
40μs/div
LCD BIAS SUPPLY CURRENT
vs. INPUT VOLTAGE
MAX1578toc09
INPUT VOLTAGE (V)
IIN
VCTRL = 0V
LCD BIAS STARTUP SEQUENCEMAX1578toc10
VONBIAS
VPOS
VNEG
VMAIN
5V/div
5V/div
10V/div
5V/div
10ms/div
BOOST STARTUP AND
SHUTDOWN WAVEFORMSMAX1578toc07
VCTRL
IIN
VOUT
VIN
AC-COUPLED
2V/div
5V/div
100mA/div
20mV/div
4ms/div
LED CURRENT vs.
DIRECT-PWM DUTY CYCLE
MAX1578toc05
PWM DUTY CYCLE (%)
ILED
(mA)
fPWM = 200Hz TO 200kHz
BOOST-SWITCHING WAVEFORMSMAX1578toc06VIN
AC-COUPLED
VLX
VOUT
AC-COUPLED
20mV/div
10V/div
200mV/div
400ns/div
MAX1578/MAX1579
Complete Bias and White LED Power Supplies
for Small TFT DisplaysPOS
NEG
POS AND NEG LOAD REGULATION
MAX1578toc12
LOAD CURRENT (μA)
VOLTAGE DROOP (%)
MAIN OUTPUT LOAD REGULATION
MAX1578toc11
LOAD CURRENT (mA)
VOLTAGE DROOP (%)51520
PINNAMEFUNCTIONMAINLDO Output and the POS and NEG Charge-Pump Inputs. VMAIN is regulated to 5V. Bypass to GND
with a 1µF capacitor. Output is internally discharged with a 1kΩ resistor when VONBIAS = 0V.CU1POS Charge-Pump Capacitor Connection 1. Connect a 1µF capacitor between CU1 and PMP.CU2POS Charge-Pump Capacitor Connection 2. Connect a 1µF capacitor between CU2 and PMPB.CU3POS Charge-Pump Capacitor Connection 3. Connect a 1µF capacitor between CU3 and GND.POSOutput of Positive (3x) Charge Pump. Bypass POS to GND with a 1µF capacitor. POS is internally
discharged with a 3kΩ resistor when VONBIAS = 0V.
6PMPCharge-Pump Capacitor Connection. Connect a 1µF capacitor between PMP and CU1 and another
1µF capacitor between PMP and CD1.PMPBCharge-Pump Capacitor Connection. Connect a 1µF capacitor between PMPB and CU2 and another
1µF capacitor between PMPB and CD2. PMPB is 180° out of phase with PMP.CD1NEG Charge-Pump Capacitor Connection 1. Connect a 1µF capacitor and a 200Ω ±5% resistor in
series between CD1 and PMP.CD2NEG Charge-Pump Capacitor Connection 2. Connect a 1µF capacitor and a 200Ω ±5% resistor in
series between CD2 and PMPB.NEGOutput of Inverting (-2x) Charge Pump. Bypass NEG to GND with a 1µF capacitor. Output is internally
discharged with a 1.5kΩ resistor when VONBIAS = 0V.
Pin Descriptionypical Operating Characteristics (continued)(Circuit of Figure 3, VIN= 3.6V, ILED= 20mA, 4 LEDs, CTRL = IN, TA= +25°C, unless otherwise noted.)
MAX1578/MAX1579
Complete Bias and White LED Power Supplies
for Small TFT Displays
PINNAMEFUNCTIONONBIASLogic Input to Enable VDD, MAIN, POS, and NEG Charge Pumps. Drive ONBIAS high to enable all the
charge pumps. Connect to GND to disable the charge pumps.GNDGround. Connect to PGND and the exposed pad directly under the IC.COMPLED Driver Compensation. Connect a 0.1µF from COMP to GND. CCOMP stabilizes the driver and
sets the soft-start time.CS
Current-Sense Feedback Input. Connect a resistor from CS to GND to set the LED current. For the
MAX1578, CS regulates to VCTRL / 5 or 0.327V, whichever is lower. For the MAX1579, CS regulates to
VCTRL / 5 or 0.340V, whichever is lower.CTRL
LE D Br i g htness C ontr ol Inp ut. C onnect C TRL to a 0.24V to 1.65V i np ut to set the b r i g htness of the
exter nal LE D s. H ol d C TRL b el ow 100m V for m or e than 10.5m s, to shut d ow n the LE D d r i ver . D r i ve C TRLi th a 200H z to 200kH z unfi l ter ed P W M d i m m i ng si g nal for D C LE D cur r ent that i s p r op or ti onal to the
si g nal ’ s d uty cycl e.OUTOver vol tag e S ense Inp ut. The M AX 1578/M AX 1579 tur n off the n- channel M OS FE T w hen V OU T exceed s 34V .
Once V OU T d r op s b el ow 32V , the IC r e- enter s soft- star t. Byp ass OU T to GN D w i th a 0.1µF cap aci tor .LXInductor Connection. Connect to the switched side of the external inductor as well as the anode of the
external diode. LX is high impedance during shutdown.PGNDPower Ground. Connect to GND and the exposed pad directly under the IC.C1NMain Charge-Pump Transfer Capacitor Negative Connection 1. Connect a 2.2µF capacitor between
C1N and C1P.C2NMain Charge-Pump Transfer Capacitor Negative Connection 2. Connect a 2.2µF capacitor between
C2N and C2P.INP ow er - S up p l y Inp ut. C onnect to a 2.7V to 5.5V i np ut sup p l y. Byp ass IN to GN D w i th a 4.7µF cap aci tor .C2PMain Charge-Pump Transfer Capacitor Positive Connection 2. Connect a 2.2µF capacitor between
C2P and C2N.C1PMain Charge-Pump Transfer Capacitor Positive Connection 1. Connect a 2.2µF capacitor between
C1P and C1N.VDDRegulated Main Charge-Pump Output. VDD is regulated to 5.5V. Bypass VDD to GND with a 4.7µF
capacitor. VDD is connected to IN when ONBIAS is pulled low.EPExposed Paddle. Connect directly to a ground plane, GND, and PGND directly under the IC.
Pin Description (continued)
