MAX1848EVKIT

MAX1848EVKIT Datasheet

Evaluates MAX1848

Part	Datasheet
MAX1848EVKIT	MAX1848EVKIT (pdf)

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Evaluates MAX1848 MAX1848 Evaluation Kit The MAX1848 evaluation kit EV kit is a fully assembled and tested circuit board that contains a step-up switching-regulator current source powering three series-connected white LEDs. The circuit provides programmable LED current. The EV kit can be powered from a 2.6VDC to 5.5VDC source. The MAX1848 features programmable soft-start and LED brightness control. The MAX1848 EV kit demonstrates matching LED brightness with high converter efficiency 87% to maximize battery life. Operation at 1.2MHz allows the use of tiny surface-mount components. o >87% Efficiency o 2.6V to 5.5V Input Voltage Range o Analog LED Intensity Control o Drives Up to Three Series White LEDs with Uniform Brightness o Small, Low-Profile External Components o 0.3µA IC Shutdown Current typ o 1.2MHz Switching Frequency o 8-Pin SOT23 Package o Fully Assembled and Tested Component Suppliers SUPPLIER Central Murata PHONE 631-435-1110 770-436-1300 FAX 631-435-1824 770-436-3030 Taiyo Yuden 800-348-2496 847-925-0899 Note Please indicate that you are using the MAX1848 when contacting these component suppliers. PART MAX1848EVKIT Ordering Information TEMP RANGE 0°C to +70°C IC PACKAGE 8 SOT23 DESIGNATION QTY 3.3µF, 6.3V X5R ceramic capacitor 1 0805 Taiyo Yuden JMK212BJ335MG 1.0µF, 16V X5R ceramic capacitor 1 0805 Taiyo Yuden EMK212BJ105KG 0.22µF, 10V X7R ceramic capacitor 1 0603 Taiyo Yuden LMK107BJ224KA 1000pF, 50V X7R ceramic 1 capacitor 0603 Taiyo Yuden UMK107B102KZ 0.2A, 30V high-speed switching diode SOD-323 Central Semiconductor Corp. CMDSH2-3 Component List DESIGNATION QTY D2, D3, D4 Right angle white LEDs SMD 2.8mm x 1.2mm x 1mm 47µH, 170mA inductor low cost 1 Murata LQH3C470K34 33µH optimum performance R1 U1 None 1 ±1% resistor 0805 1 MAX1848EKA 8-pin SOT23 1 MAX1848 PC board 1 MAX1848 data sheet 1 MAX1848 EV kit data sheet Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at Evaluates MAX1848 MAX1848 Evaluation Kit Quick Start The MAX1848 EV kit is fully assembled and tested. Follow these steps to verify board operation. Do not turn on the power supply until all connections are completed. Recommended Equipment • One voltmeter • Dual power supply 5V, 1A Main Output 1 Connect a voltmeter to the VOUT pad. 2 Make sure both power supplies are set to 0V and off before connecting the power supplies to the circuit. 3 Connect a 5V supply to the VIN pad. Connect the power-supply ground to the GND pad. 4 Connect a 5V supply to the VCTRL pad. Connect the power-supply ground to the GND pad. 5 Turn on the VIN power supply and set it to 3.3V. 6 Turn on the VCTRL power supply, vary the VCTRL between 0 and 2V and observe the variation in brightness of the LEDs. 7 Verify that the output, VOUT is approximately 10V when the VCTRL power supply is 2V. 8 Vary the VIN power supply from 2.6V to 5.5V and verify that the LED brightness remains constant. 9 Verify that the LEDs are off when VCTRL drops below 100mV. Detailed Description The MAX1848 EV kit contains a switching-regulator current-source circuit. The EV kit’s circuit is configured to drive three series-connected LEDs. The EV kit can be powered by a 2.6V to 5.5V DC source. The MAX1848 EV kit features programmable LED brightness by controlling LED current, overvoltage protection, and up to 87% efficiency for maximum battery life. Soft-Start The soft-start feature limits the inrush current during startup. Capacitor C3 determines the startup delay time for the EV kit. The delay time for the EV kit is set to 18.3ms. The following equation can be used to configure the EV kit for other startup times: t = C3 x 1V / 12µA where t = desired startup time delay LED Current The current through the LEDs is related to the currentsense resistor R1 by the following equation: ILED = VCTRL / x R1 Adjusting the control voltage VCTRL varies the intensity of the LEDs. VCTRL can range from 250mV to 5.5V or VIN + 2V , whichever is lower. However, with R1 = VCTRL should not exceed +2V in order to keep the LED current below its absolute maximum rating of 30mA. Shutdown The MAX1848 enters shutdown mode when VCTRL drops below 100mV. In shutdown mode, the MAX1848 quiescent current is reduced to 0.3µA. The MAX1848 comes out of shutdown mode when VCTRL rises above 250mV. Overvoltage Protection Overvoltage protection occurs when VOUT is above 13.25V typ . The EV kit comes out of the overvoltage protection when VOUT falls below 12.25V typ . This protects the MAX1848 and white LEDs during a fault condition. Evaluates MAX1848 MAX1848 Evaluation Kit VIN 2.6V TO 5.5V GND VCTRL C1 3.3µF C4 1000pF C3 0.22µF L1 47µH D1 4 LX 2 CTRL MAX1848 PGND 5 1 COMP 6 GND Figure MAX1848 EV Kit Schematic C2 1µF

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Evaluates MAX1848

MAX1848 Evaluation Kit

The MAX1848 evaluation kit EV kit is a fully assembled and tested circuit board that contains a step-up switching-regulator current source powering three series-connected white LEDs. The circuit provides programmable LED current. The EV kit can be powered from a 2.6VDC to 5.5VDC source.

The MAX1848 features programmable soft-start and LED brightness control. The MAX1848 EV kit demonstrates matching LED brightness with high converter efficiency 87% to maximize battery life. Operation at 1.2MHz allows the use of tiny surface-mount components.
o >87% Efficiency o 2.6V to 5.5V Input Voltage Range o Analog LED Intensity Control o Drives Up to Three Series White LEDs with

Uniform Brightness o Small, Low-Profile External Components o 0.3µA IC Shutdown Current typ o 1.2MHz Switching Frequency o 8-Pin SOT23 Package o Fully Assembled and Tested

Component Suppliers

SUPPLIER Central Murata

PHONE 631-435-1110 770-436-1300

FAX 631-435-1824 770-436-3030

Taiyo Yuden
800-348-2496
847-925-0899

Note Please indicate that you are using the MAX1848 when contacting these component suppliers.

PART MAX1848EVKIT
Ordering Information

TEMP RANGE 0°C to +70°C

IC PACKAGE 8 SOT23

DESIGNATION QTY
3.3µF, 6.3V X5R ceramic capacitor
1 0805

Taiyo Yuden JMK212BJ335MG
1.0µF, 16V X5R ceramic capacitor
1 0805

Taiyo Yuden EMK212BJ105KG
0.22µF, 10V X7R ceramic capacitor
1 0603

Taiyo Yuden LMK107BJ224KA
1000pF, 50V X7R ceramic
1 capacitor 0603

Taiyo Yuden UMK107B102KZ
0.2A, 30V high-speed switching
diode SOD-323 Central Semiconductor Corp.

CMDSH2-3

Component List

DESIGNATION QTY

D2, D3, D4

Right angle white LEDs SMD 2.8mm x 1.2mm x 1mm
47µH, 170mA inductor low cost
1 Murata LQH3C470K34
33µH optimum performance

R1 U1 None
1 ±1% resistor 0805 1 MAX1848EKA 8-pin SOT23 1 MAX1848 PC board 1 MAX1848 data sheet 1 MAX1848 EV kit data sheet

Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at

Evaluates MAX1848

MAX1848 Evaluation Kit

Quick Start

The MAX1848 EV kit is fully assembled and tested. Follow these steps to verify board operation. Do not turn on the power supply until all connections are completed.

Recommended Equipment
• One voltmeter
• Dual power supply 5V, 1A

Main Output 1 Connect a voltmeter to the VOUT pad.
2 Make sure both power supplies are set to 0V and off before connecting the power supplies to the circuit.
3 Connect a 5V supply to the VIN pad. Connect the power-supply ground to the GND pad.
4 Connect a 5V supply to the VCTRL pad. Connect the power-supply ground to the GND pad.
5 Turn on the VIN power supply and set it to 3.3V.
6 Turn on the VCTRL power supply, vary the VCTRL between 0 and 2V and observe the variation in brightness of the LEDs.
7 Verify that the output, VOUT is approximately 10V when the VCTRL power supply is 2V.
8 Vary the VIN power supply from 2.6V to 5.5V and verify that the LED brightness remains constant.
9 Verify that the LEDs are off when VCTRL drops below 100mV.

Detailed Description

The MAX1848 EV kit contains a switching-regulator current-source circuit. The EV kit’s circuit is configured to drive three series-connected LEDs. The EV kit can be powered by a 2.6V to 5.5V DC source.

The MAX1848 EV kit features programmable LED brightness by controlling LED current, overvoltage protection, and up to 87% efficiency for maximum battery life.

Soft-Start The soft-start feature limits the inrush current during startup. Capacitor C3 determines the startup delay time for the EV kit. The delay time for the EV kit is set to 18.3ms. The following equation can be used to configure the EV kit for other startup times:
t = C3 x 1V / 12µA
where t = desired startup time delay

LED Current The current through the LEDs is related to the currentsense resistor R1 by the following equation:

ILED = VCTRL / x R1

Adjusting the control voltage VCTRL varies the intensity of the LEDs. VCTRL can range from 250mV to 5.5V or VIN + 2V , whichever is lower. However, with R1 = VCTRL should not exceed +2V in order to keep the LED current below its absolute maximum rating of 30mA.

Shutdown The MAX1848 enters shutdown mode when VCTRL drops below 100mV. In shutdown mode, the MAX1848 quiescent current is reduced to 0.3µA. The MAX1848 comes out of shutdown mode when VCTRL rises above 250mV.

Overvoltage Protection Overvoltage protection occurs when VOUT is above 13.25V typ . The EV kit comes out of the overvoltage protection when VOUT falls below 12.25V typ . This protects the MAX1848 and white LEDs during a fault condition.

Evaluates MAX1848

MAX1848 Evaluation Kit

VIN 2.6V TO 5.5V

GND VCTRL

C1 3.3µF

C4 1000pF

C3 0.22µF

L1 47µH

D1 4 LX
2 CTRL MAX1848 PGND 5
1 COMP
6 GND

Figure MAX1848 EV Kit Schematic

C2 1µF

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Datasheet ID: MAX1848EVKIT 647264