MAX38889 datasheet(4/9 Pages) MAXIM

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MAX38889A Evaluation Kit

Evaluates: MAX38889

www.maximintegrated.com

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Ready Mode

The MAX38889A EV kit maximum supercapacitor voltage is set to 2.7V by resistors R1, R2, and R3 with VFBCH = 0.5V.

Once the sup

ercapacitor is charged to the set maximum charge voltage of 2.7V, the MAX38889 consumes only 4μA

current. The MAX38889A EV kit provides a RDY test point to monitor the supercapacitor charge status. The RDY test

point will be high when the voltage of the FBCR pin crosses the FBCR threshold (VTH_FBCR = 0.5V) set by R1, R2, and

R3. In this EV kit, the VCAP at which RDY goes high is 1.5V. Similarly, when the supercapacitor is providing backup, the

RDY flag goes low when the supercapacitor discharges below 1.5V.

Discharge (Backup) Mode

When the main battery is removed and VFBS drops to 1.2V, the MAX38889 draws power from the supercapacitor and

regulates the VSYS to the set backup voltage. The backup voltage is set to 3V by resistors R5 and R6 with VFBS = 1.2V.

The MAX38889A EV kit provides a BKB test point to monitor the system backup status. BKB is pulled low when the

system is backing up (the supercapacitor is discharging) and pulled high when the system is charging or in idle state.

Charge/Backup Current Configuration

The MAX38889A EV kit provides a resistor R4 to configure the charge/backup peak inductor current.

The peak inductor current is set by resistor R4 connecting between the ISET and GND pins.

LX _ CHG

33k

Peak charging current (I

)



= 



LX _ BU

33k

Peak backup current (I

)



= 



Set R4 to 33kΩ to ensure accurate current compliance.

Ordering Information

PART

TYPE

MAX38889AEVKIT#

EV Kit

#Denotes RoHS-compliant.

Component Suppliers

SUPPLIER

WEBSITE

AVX

www.avx.com

Kemet

www.kemet.com

Murata/TOKO

www.murata.com

Wurth Electronics

www.we-online.com

Note: Indicate that you are using the MAX38889A when contacting these component suppliers.

MAX38889 Datasheet(PDF) 4 Page - Maxim Integrated Products

MAX38889 Datasheet(HTML) 4 Page - Maxim Integrated Products

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