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MAX1585ETJ ,5-Channel Slim DSC Power SuppliesFeaturesThe MAX1584/MAX1585 provide a complete power- Step-Up DC-DC Converter, 95% Efficient suppl ..
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MAX4245AXT ,Ultra-Small, Rail-to-Rail I/O with Disable, Single/Dual-Supply, Low-Power Op AmpsElectrical Characteristics(V = +2.7V, V = 0V, V = 0V, V = V /2, R connected from OUT to V /2, SHDN_ ..
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MAX1582ETC+-MAX1582ETC+T-MAX1582ETC-T
High-Efficiency Step-Up Converters for White LED Main and Subdisplay Backlighting
General DescriptionThe MAX1582/MAX1582Y drive up to six white LEDs in
series with a constant current to provide display back-
lighting for two (main and sub-) displays in cell phones
and other handheld devices. This configuration elimi-
nates the need for ballast resistors and expensive fac-
tory calibration. The proprietary dual-output, step-up
pulse-width modulation (PWM) converter includes a low
RDSONn-channel MOSFET switch for high efficiency and
maximum battery life.
The MAX1582/MAX1582Y utilize 1MHz current-mode
PWM control to allow small input and output capacitors
and a small inductor, while minimizing ripple on the input
supply and avoiding interference to sensitive circuitry in
the equipment. Integrated overvoltage protection (27V
for the MAX1582 and 18V for the MAX1582Y) eliminates
the need for an external zener diode to protect the IC
from open circuit. Flexible dimming control utilizes either
an analog control signal or direct digital PWM control
without external RC filtering. This also increases dimming
accuracy at low brightness levels. The PWM dimming
signal can be any frequency from 200Hz to 200kHz. Soft-
start eliminates inrush current during startup.
The MAX1582/MAX1582Yare available in tiny 4 ✕4
chip-scale (UCSP™) and 12-pin thin QFN packages.
ApplicationsCell Phones with One or Two Displays
Smart Phones, Palmtops, and WirelessHandhelds
Other Handheld Devices with Dual Displays
FeaturesAccurate Current Regulation for Uniform
IlluminationLights Up Two LED Sections for Main and
SubdisplaysUp to 84% EfficiencyInternal High-Power, 30V MOSFETLow 15mVP-PInput RippleFlexible Dimming Control
Analog DAC Controlled
Direct-Digital PWM (No RC Required)
from 200Hz to 200kHzOvervoltage Protection to Eliminate Zener DiodeConstant 1MHz PWM OperationLow-Profile Inductor and CapacitorsSoft-Start Eliminates Inrush Current2.6V to 5.5V Input0.01µA (typ) Shutdown CurrentTiny UCSP (2.1mm ✕2.1mm ✕0.61mm) and Thin
QFN (4mm ✕4mm) Packages
MAX1582/MAX1582Y
High-Efficiency Step-Up Converters
for White LED Main and Subdisplay Backlighting
Ordering Information19-2783; Rev 2; 8/05
EVALUATION KIT
AVAILABLE
PARTTEMP RANGEPIN-PACKAGETOP
MARKA X1 5 8 2 E BE - T-40°C to +85°C16 UCSP-161582EBEAX 1582E BE + T-40°C to +85°C16 UCSP-161582EBE
MAX1582ETC-40°C to +85°C12 Thin QFN-EP*AACE
MAX1582ETC+-40°C to +85°C12 Thin QFN-EP*AACE
Pin ConfigurationsMAX1582
INPUT
2.6V TO 5.5V
2.2μF
0.022μF
0.1μF
CTRL
EN1
EN2
COMP
22μH
OUT1
PGND
OUT2
GND
2 TO 4 LEDSMAIN
DISPLAY
2 TO 3 LEDSSUB-
DISPLAY
7.5Ω
ANALOG OR
DIRECT PWM
DIMMING
Typical Application CircuitMAX1582
MAX1582YV+
TOP VIEWVPCTRL
OUT2
EN211106
PGNDLXOUT1
COMP
GND
EN1
4mm x 4mm
THIN QFNA "+" SIGN WILL REPLACE THE FIRST PIN INDICATOR ON LEAD-FREE PACKAGES.
Pin Configurations continued at end of data sheet.
*EP = Exposed paddle.
+Denotes lead-free package.
UCSP is a trademark of Maxim Integrated Products, Inc.
Ordering Information continued at end of data sheet.
MAX1582/MAX1582Y
High-Efficiency Step-Up Converters
for White LED Main and Subdisplay Backlighting
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(VV+= +3.0V, VOUT1 = 20V, L1 = 22µH, COUT = 0.1µF, CCOMP = 0.022µF, RSENSE = 7.5Ω, VCTRL = +1.5V, EN1 = EN2 = V+, TA =
0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (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.
V+, VP, CTRL to GND............................................-0.3V to +6.0V
PGND to GND.......................................................-0.3V to +0.3V
LX, OUT1 to GND...................................................-0.3V to +30V
OUT2 to GND.........................................................-0.3V to +14V
COMP, CS, EN1, EN2 to GND....................-0.3V to (VV++ 0.3V)
ILX....................................................................................................1ARMS
Continuous Power Dissipation (TA = +70°C)
12-Pin Thin QFN (derate 16.9mW/°C above +70°C)....1349mW
16-Pin UCSP (derate 6.5mW/°C above +70°C)..............518mW
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
PARAMETERCONDITIONSMINTYPMAXUNITSSupply Voltage2.65.5V
Undervoltage Lockout (UVLO)
ThresholdV+ rising or falling2.102.382.55V
UVLO Hysteresis40mV
Quiescent CurrentNo switching, VCTRL = VCS = +0.25V0.400.56mA
TA = +25°C0.011Shutdown Supply CurrentEN1 = EN2 = GND, OUT1 = V+TA = +85°C0.1µA
MAX1582262729Overvoltage Lockout (OVLO)
Threshold (Rising)MAX1582Y171819V
MAX15822OVLO HysteresisMAX1582Y1.3V
MAX1582, VOUT1 = +26V, EN1 = EN2 = V+204065
MAX1582Y, VOUT1 = +16V, EN1 = EN2 = V+204065
TA = +25°C0.011OUT1 Input Bias Current
OUT1 = V+, EN1 = EN2 = GNDTA = +85°C0.05
MAX1582(VV+ -
VDIODE)25.5
Output Voltage Range (Note 2)
MAX1582Y(VV+ -
VDIODE)17.0
ERROR AMPLIFIERCTRL to CS RegulationVCTRL = +1.0V, VV+ = +2.6V to +5.5V0.0950.1000.106V
TA = +25°C0.011CS Input Bias CurrentVCS = VCTRL / 10TA = +85°C1µA
CTRL Input Resistance0 < VCTRL < +1V290500780kΩ
CS to COMP TransconductanceVCOMP = +1.0V325082µS
OSCILLATOROperating Frequency0.801.01.25MHz
PWM mode12Minimum Duty CyclePulse skipping0%
Maximum Duty CycleCTRL = V+, CS = GND9194%
MAX1582/MAX1582Y
High-Efficiency Step-Up Converters
for White LED Main and Subdisplay Backlighting
ELECTRICAL CHARACTERISTICS (continued)(VV+= +3.0V, VOUT1 = 20V, L1 = 22µH, COUT = 0.1µF, CCOMP = 0.022µF, RSENSE = 7.5Ω, VCTRL = +1.5V, EN1 = EN2 = V+, TA =
0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
PARAMETERCONDITIONSMINTYPMAXUNITS
N-CHANNEL SWITCHLX On-Resistance1.502.25Ω
TA = +25°C0.015LX Leakage CurrentVLX = +28VTA = +85°C0.02µA
LX Current LimitDuty cycle = 90%450650950mA
MAIN AND SUBDISPLAY ON/OFF SWITCHESOUT1 to OUT2 On-ResistanceEN1 = GND, EN2 = V+2.5Ω
OUT2 to CS On-ResistanceEN1 = V+, EN2 = GND2.5Ω
OUT1 to OUT2 Leakage CurrentE N 1 = E N 2 = V + , V OU T 1 = 25V , V OU T 2 = + 9V , TA = + 85° C 0.05µA
OUT2 to CS Leakage CurrentEN1 = EN2 = V+, VOUT2 = 12V, VCS = 0, TA = +85°C0.05µA
EN1 and EN2 Logic Input Voltage
High+2.6V < VV+ < +5.5V1.6V
EN1 and EN2 Logic Input Voltage
Low+2.6V < VV+ < +5.5V0.6V
TA = +25°C0.021EN1 and EN2 Input LeakageVV+ = VEN1 = VEN2 = +5.5VTA = +85°C0.1µA
ELECTRICAL CHARACTERISTICS (VV+= +3.0V, VOUT1 = +20V, L1 = 22µH, COUT = 0.1µF, CCOMP = 0.022µF, RSENSE = 7.5Ω, VCTRL = +1.5V, EN1 = EN2 = V+, TA =
-40°C to +85°C, unless otherwise noted.) (Notes 1, 3)
PARAMETERCONDITIONSMINMAXUNITSSupply Voltage2.65.5V
Undervoltage Lockout (UVLO)
ThresholdV+ rising or falling2.102.55V
Quiescent CurrentNo switching, VC = +0.25V0.56mA
MAX15822629Overvoltage Lockout (OVLO)
Threshold (Rising)MAX1582Y1719V
OUT1 Input Bias CurrentVOUT1 = +26V, EN1 = EN2 = V+2065µA
ERROR AMPLIFIERCTRL to CS RegulationVCTRL = +1.0V, VV+ = +2.6V to +5.5V0.0930.107V
CTRL Input Resistance0 < VCTRL < +1.0V290780kΩ
CS to COMP TransconductanceVCOMP = 1.0V3285µS
OSCILLATOROperating Frequency0.751.30MHz
EFFICIENCY vs. LED CURRENT
(vs. NUMBER of LEDs)
MAX1582 toc01
LED CURRENT (mA)
EFFICIENCY (%)2 LEDs
4 LEDs
6 LEDs
EFFICIENCY vs. LED CURRENT
(vs. INPUT VOLTAGE)
MAX1582 toc02
LED CURRENT (mA)
EFFICIENCY (%)4.2 VIN
3.6 VIN
2.7 VIN
EFFICIENCY vs. LED CURRENT
(vs. INDUCTANCE)
MAX1582 toc03
LED CURRENT (mA)
EFFICIENCY (%)
10μH
4.7μH47μH
22μH1015202553035404550
INPUT RIPPLE vs. INDUCTANCEMAX1582 toc04
INDUCTANCE (μH)
INPUT RIPPLE (mV
P-P23451678910
INPUT RIPPLE SPECTRUMMAX1582 toc05
FREQUENCY (MHz)
INPUT RIPPLE (mV
RMS203040501060708090100
LED CURRENT vs. DIRECT-PWM
DIMMING DUTY CYCLEMAX1582 toc06
DIRECT-PWM DIMMING DUTY CYCLE (%)
LED CURRENT (mA)
VCTRL = SQUARE WAVE
200Hz < FREQ < 200kHz
Typical Operating Characteristics(See the Typical Applications Circuit, VV+= VVP= 3.6V, ILED= 15mA, L1 = 22µH, COUT1= 0.1µF, CCOMP= 0.022µF, RSENSE= 7.5Ω,
VCTRL= 1.5V, 4 LEDs, TA= +25°C, unless otherwise noted.)
MAX1582/MAX1582Y
High-Efficiency Step-Up Converters
for White LED Main and Subdisplay Backlighting
ELECTRICAL CHARACTERISTICS (continued)(VV+= +3.0V, VOUT1 = +20V, L1 = 22µH, COUT = 0.1µF, CCOMP = 0.022µF, RSENSE = 7.5Ω, VCTRL = +1.5V, EN1 = EN2 = V+, TA =
-40°C to +85°C, unless otherwise noted.) (Notes 1, 3)
PARAMETERCONDITIONSMINMAXUNITSMaximum Duty CycleCTRL = V+, CS = GND91%
N-CHANNEL SWITCHLX On-Resistance2.25Ω
LX Current LimitDuty cycle = 90%450950mA
Note 1:Limits are 100% production tested at TA= +25°C for UCSP parts. Limits over the entire operating temperature range are
guaranteed by design and characterization but are not production tested.
Note 2:The minimum output voltage is the input voltage minus the forward voltage drop of the Schottky diode:
VOUT(MIN)= VV+- VDIODE
Note 3:Specifications to -40°C are guaranteed by design and not production tested.
MAX1582/MAX1582Y
High-Efficiency Step-Up Converters
for White LED Main and Subdisplay Backlighting
Pin Description
SWITCHING WAVEFORMSMAX1582 toc07
VIN
10mV/div
VOUT
100mV/div
VLX
10V/div
500ns/div
DIRECT-PWM DIMMINGMAX1582 toc08
VCTRL
32kHz
1V/div
IIN
50mA/div
VIN
50mV/div
VOUT
5V/div
0mA
50μs/div
VIN = 3.8V Li+ BATTERY
Typical Operating Characteristics (continued)(See the Typical Applications Circuit, VV+= VVP= 3.6V, ILED= 15mA, L1 = 22µH, COUT1= 0.1µF, CCOMP= 0.022µF, RSENSE= 7.5Ω,
VCTRL= 1.5V, 4 LEDs, TA= +25°C, unless otherwise noted.)
PIN
QFNUCSPNAMEFUNCTION1A1V+Input Voltage Supply. Input voltage range is 2.6V to 5.5V. Connect a 2.2µF capacitor from V+ to
PGND.A2VPHigh-Current Input Supply. Connect to V+.
3A3CTRL
Brightness Control Input. LED brightness is controlled by the voltage applied to CTRL. Varying the
voltage from 0 to +1.62V adjusts the brightness from dim to bright, respectively. Any voltage
above +1.62V does not increase brightness.
4A4COMPCompensation Input. Connect a 0.022µF capacitor (CCOMP) from COMP to GND. CCOMP
stabilizes the converter and controls soft-start. CCOMP discharges to GND when in shutdown.B4GNDGround. Connect to PGND at a single point near the IC.C4EN1Enable 1 Input. Drive EN1 high to enable the main-display LEDs. Pull EN1 low to turn off the main-
display LEDs. Pull both EN1 and EN2 low to place the IC in low-current shutdown mode.D4EN2Enable 2. Drive EN2 high to enable the subdisplay LEDs. Pull EN2 low to turn off the subdisplay
LEDs. Pull both EN1 and EN2 low to place the IC in low-current shutdown mode.
8D3CSCurrent-Sense Feedback Input. Connect a resistor (RSENSE) from CS to GND to set the LED bias
current. The voltage at CS regulates to VCTRL / 10 or +0.162V, whichever is lower.
9D2OUT2
Display Switch Output. OUT2 is internally connected to CS when only the main display is lit. OUT2
is internally connected to OUT1 when only the subdisplay is lit. OUT2 is high impedance when
both displays are lit and when the IC is shut down.D1OUT1
Overvoltage Sense. When VOUT1 is greater than 27V (18V on the MAX1582Y), the internal
n-channel MOSFET turns off until VOUT1 drops below 25V (16.7V on the MAX1582Y), then the IC
re-enters soft-start. Connect a 0.1µF capacitor from OUT1 to PGND.C1LXInductor Connection. During shutdown, this pin is high impedance.B1PGNDPower Ground. Connect to GND at a single point near the IC.—EPExposed Paddle. Connect directly to GND and PGND under the IC.
MAX1582/MAX1582Y
Detailed DescriptionThe MAX1582’s high efficiency and small size make it
ideally suited to drive up to six series-connected LEDs
(four LEDs for the MAX1582Y). Separate enable inputs
are provided to control the main and subdisplay back-
lighting. The MAX1582/MAX1582Y operate as a boost
DC-to-DC converter that regulates output current rather
than voltage. It provides even illumination by sourcing the
same output current through each LED, eliminating the
need for expensive factory calibration. The fast 1MHz
internal oscillator allows for a small inductor and small
input and output capacitors while minimizing input and
output ripple.
Shutdown for Main and SubdisplayThe MAX1582/MAX1582Yhave two enable inputs (EN1
and EN2) used to enable or shutdown the main and
subdisplay LEDs. When EN1 and EN2 are both high, all
LEDs are lit. With EN1 high and EN2 low, the main-dis-
play LEDs are lit, and the subdisplay LEDs are shorted
by the MAX1582/MAX1582Y. With EN1 low and EN2
high, the main-display LEDs are shorted and the subdis-
play LEDs are lit.
When both EN1 and EN2 are low, the MAX1582/
MAX1582Yenter shutdown, reducing supply current to
0.01µA (typ). Although the internal n-channel MOSFET
does not switch in shutdown, there is still a DC-current
High-Efficiency Step-Up Converters
for White LED Main and Subdisplay BacklightingSLOPE COMP.
CURRENT SENSE
114kΩ336kΩ
50kΩ
PWM
CONTROL
CTRL
UP TO 27V
2.6V TO 5.5V
DAC OR
PWMCOMP
OUT1
PGND
OVERVOLTAGE
PROTECTION
GND
EN1
EN2
2 TO 4 LEDS
2 TO 3 LEDS
OUT2
1.25V CLAMP
UP TO 13V
CIN
2.2μF
COUT1
0.1μF
22μF
ENABLE
INPUTS
MAIN DISPLAY
SUBDISPLAYCCOMP
0.022μF
RSENSE
7.5ΩSHUTDOWN
fOSC
1.0MHz
MAX1582
Figure 1. Functional Diagram