MAX1574ETB ,180mA / 1x/2x / White LED Charge Pump in 3mm x 3mm TDFNELECTRICAL CHARACTERISTICS(V = 3.6V, V = 0V, EN = IN, R = 13.7kΩ, T = -40°C to +85°C, unless otherw ..
MAX1574ETB ,180mA / 1x/2x / White LED Charge Pump in 3mm x 3mm TDFNApplicationsOrdering InformationLCD BacklightingPIN- TOPPART TEMP RANGEPACKAGE MARKCamera Strobes/F ..
MAX1574ETB+ ,180mA, 1x/2x, White LED Charge Pump in 3mm x 3mm TDFNELECTRICAL CHARACTERISTICS(V = 3.6V, V = 0V, EN = IN, R = 13.7kΩ, T = -40°C to +85°C, unless otherw ..
MAX1574ETB+T ,180mA, 1x/2x, White LED Charge Pump in 3mm x 3mm TDFNFeaturesThe MAX1574 charge pump drives up to three white♦ Up to 180mA (60mA/LED) Drive CapabilityLE ..
MAX1575ETE ,White LED 1x/1.5x Charge Pump for Main and Sub-DisplaysFeaturesThe MAX1575 evaluation kit (EV kit) is a fully assem-♦ Powers 4 Main and 2 Sub-Display LEDs ..
MAX1575ETE+ ,White LED 1x/1.5x Charge Pump for Main and Sub-DisplaysFeaturesThe MAX1575 charge pump drives up to four white♦ Powers Main and Sub-Display LEDsLEDs in th ..
MAX4238ASA+T ,Ultra-Low Offset/Drift, Low-Noise, Precision SOT23 AmplifiersApplications• 0.1µA Shutdown Mode● Thermocouples● Strain GaugesPin Configurations appear at end of ..
MAX4238ASA+T ,Ultra-Low Offset/Drift, Low-Noise, Precision SOT23 AmplifiersApplications• 0.1µA Shutdown Mode● Thermocouples● Strain GaugesPin Configurations appear at end of ..
MAX4238ATT+T ,Ultra-Low Offset/Drift, Low-Noise, Precision SOT23 AmplifiersMAX4238/MAX4239 Ultra-Low Offset/Drift, Low-Noise, Precision SOT23 Ampliiers
MAX4238AUT#TG16 ,Ultra-Low Offset/Drift, Low-Noise, Precision SOT23 AmplifiersElectrical Characteristics(2.7V ≤ V ≤ 5.5V, V = V = 0V, V = V /2, R = 10kΩ connected to V /2, SHDN ..
MAX4238AUT+T ,Ultra-Low Offset/Drift, Low-Noise, Precision SOT23 AmplifiersElectrical Characteristics(2.7V ≤ V ≤ 5.5V, V = V = 0V, V = V /2, R = 10kΩ connected to V /2, SHDN ..
MAX4239ASA+ ,Ultra-Low Offset/Drift, Low-Noise, Precision SOT23 AmplifiersFeaturesThe MAX4238/MAX4239 are low-noise, low-drift, ultra- ● DC Performance Ideal for High-Precis ..
MAX1574ETB
180mA / 1x/2x / White LED Charge Pump in 3mm x 3mm TDFN
General DescriptionThe MAX1574 charge pump drives up to three white
LEDs with regulated constant current for uniform intensity.
By utilizing adaptive 1x/2x charge-pump modes and
very-low-dropout current regulators, it achieves 180mA
output drive capability and high efficiency over the 1-cell
lithium-battery input voltage range. Fixed-frequency
(1MHz) switching allows for tiny external components,
and the regulation scheme is optimized to ensure low EMI
and low input ripple.
The MAX1574 uses an external resistor to set the full-
scale 100% LED current. An enable input (EN) is used for
simple on/off control or can be pulsed repeatedly to set
lower LED current in multiple steps down to 5%. Once the
desired brightness is set, the MAX1574 maintains con-
stant LED current as long as EN is kept high. If EN is kept
low for more than 2ms, the MAX1574 enters shutdown.
The MAX1574 is available in a 10-pin 3mm x 3mm TDFN
package (0.8mm max height).
ApplicationsLCD Backlighting
Camera Strobes/Flashes and Movie Lights
Cell Phones/Smart Phones
PDAs, Digital Cameras, and Camcorders
FeaturesUp to 180mA (60mA/LED) Drive Capability83% Average Efficiency (PLED / PBATT) Over Li+
Battery Discharge0.5% (typ) LED Current MatchingAdaptive 1x/2x Mode SwitchoverLow Input Ripple and EMI5% to 100% Dimming Through Single-Wire Serial
Pulse InterfaceLow 0.1µA Shutdown Current2.7V to 5.5V Supply Voltage RangeSoft-Start Limits Inrush CurrentOutput Overvoltage ProtectionThermal-Shutdown Protection10-Pin 3mm x 3mm TDFN Package
MAX1574
180mA, 1x/2x, White LED Charge Pump
in 3mm x 3mm TDFN
Pin Configuration
Ordering Information
Typical Operating Circuit
MAX1574
180mA, 1x/2x, White LED Charge Pump
in 3mm x 3mm TDFN
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(VIN= 3.6V, VGND= 0V, EN = IN, RSET= 13.7kΩ, TA= -40°C to +85°C,unless otherwise noted. Typical values are at TA= +25°C.)
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, OUT, EN to GND..............................................-0.3V to +6.0V
SET, LED1, LED2, LED3, CN to GND.........-0.3V to (VIN + 0.3V)
CP to GND ......................................................................-0.3V to
the greater of (VOUT+ 1V) or (VIN + 1V)
OUT Short Circuit to GND..........................................Continuous
Continuous Power Dissipation (TA = +70°C)
10-Pin TDFN (derate 18.2mW/°C above +70°C).......1454mW
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
MAX1574
180mA, 1x/2x, White LED Charge Pump
in 3mm x 3mm TDFN
Note 2:LED current matching is defined as: (ILED- IAVG) / IAVG
Note 3:Dropout voltage is defined as the LED_-to-GND voltage at which current into LED_ drops 10% from the value at VLED_= 0.2V.
ELECTRICAL CHARACTERISTICS (continued)(VIN= 3.6V, VGND= 0V, EN = IN, RSET= 13.7kΩ, TA= -40°C to +85°C,unless otherwise noted. Typical values are at TA= +25°C.)
(Note 1)
Typical Operating Characteristics(Circuit of Figure 2, VIN= 3.6V, EN = IN, driving three white LEDs, TA= +25°C, unless otherwise noted.)
MAX1574
180mA, 1x/2x, White LED Charge Pump
in 3mm x 3mm TDFN
Typical Operating Characteristics (continued)(Circuit of Figure 2, VIN= 3.6V, EN = IN, driving three white LEDs, TA= +25°C, unless otherwise noted.)
MAX1574
180mA, 1x/2x, White LED Charge Pump
in 3mm x 3mm TDFN
Typical Operating Characteristics (continued)(Circuit of Figure 2, VIN= 3.6V, EN = IN, driving three white LEDs, TA= +25°C, unless otherwise noted.)
MAX1574
Detailed DescriptionThe MAX1574 charge pump drives up to three white
LEDs with regulated constant current for uniform inten-
sity. By utilizing adaptive 1x/2x charge-pump modes
and very-low-dropout current regulators, it achieves
180mA output drive capability and high efficiency over
the 1-cell lithium-battery input voltage range. Fixed-fre-
quency switching of 1MHz allows for tiny external com-
ponents, and the regulation scheme is optimized to
ensure low EMI and low input ripple.
1x to 2x SwitchoverWhen VINis higher than VOUT, the MAX1574 operates in
1x mode and VOUTis pulled up to VIN. The internal cur-
rent regulators regulate the LED current. As VINdrops,
VLED_eventually falls below the switchover threshold of
130mV, and the MAX1574 starts switching in 2x mode.
When the input voltage rises above VOUTby approxi-
mately 50mV, the MAX1574 switches back to 1x mode.
Soft-StartThe MAX1574 includes soft-start circuitry to limit inrush
current at turn-on. When starting up, the output capacitor
is charged directly from the input with a ramped current
source (with no charge-pump action) until the output volt-
age approaches the input voltage. Once this occurs, the
charge pump determines if 1x or 2x mode is required. In
the case of 1x mode, the soft-start is terminated and nor-
mal operation begins. During the soft-start time, the out-
put current is set to 5% of the maximum set by RSET. In
the case of 2x mode, soft-start operates until the lowest of
LED1 to LED3 reaches regulation. If an overload condi-
tion occurs, soft-start repeats every 2.1ms. If the output is
shorted to ground, the output current is limited by the
MAX1574 switching technique.
Setting the Output CurrentThe LED current at full brightness is set by a resistor,
RSET, as follows:
EN Dimming ControlWhen the LEDs are enabled by driving EN high, the
MAX1574 goes through soft-start, bringing the LED cur-
rent up to ILED_. Dimming is then done by pulsing EN
low (500ns to 500µs pulse width). Each pulse reduces
the LED current by 10%, so after one pulse the LED cur-
rent is 0.9 x ILED. The tenth pulse reduces the current by
5%, so the ILED_current reduces from 0.1 x ILED_to 0.05
x ILED. The eleventh pulse sets the LED current back to
ILED_. Figure 1 shows a timing diagram for EN.
If dimming control is not required, EN works as a simple
on/off control. Drive EN high to enable the LEDs, or
drive EN low for shutdown.
Shutdown ModeWhen EN is held low for 2ms or longer, the MAX1574
is shut down and put in a low-current mode. OUT is
internally pulled to GND with 5kΩduring shutdown.
Overvoltage ProtectionIf any LED fails as an open circuit, the output voltage is
limited to about 5V by gating on/off the charge pump.
If any LED_ is floating or grounded, the MAX1574 oper-
ates in the same overvoltage-protection mode. To avoid
overvoltage-protection mode when using fewer than
three LEDs, connect any unused LED_ to IN (Figure 3).
Thermal ShutdownThe MAX1574 includes a thermal-limit circuit that shuts
down the IC at approximately+160°C. The part turns on
after the IC cools by approximately 20°C.
180mA, 1x/2x, White LED Charge Pump
in 3mm x 3mm TDFN
