MAX1800EVKIT Maxim Integrated, MAX1800EVKIT Datasheet - Page 5

• Manufacturer Part Number: MAX1800EVKIT
• Description: Power Management IC Development Tools
• Manufacturer: Maxim Integrated
• Series: MAX1800r

Also, note that the voltages at MAIN, OUT3, and OUT4
will drop slightly below the battery voltage when OFF,
due to the DC current path through the inductor and
output rectifier. For the step-up outputs, a switch may
be added between the output voltage and the load to
disconnect them while the output is disabled.
The MAIN output is designed to operate with an input
voltage above or below the output regulation voltage.
Since MAIN is a step-up converter, when the input volt-
age is above the regulation voltage, the output will be
nearly that of the input voltage. If the input battery volt-
age ranges above and below the regulation voltage,
follow the MAIN output with the LDO output to form a
step-up/step-down regulator. In this case, when the
battery voltage is low, the step-up converter raises the
battery voltage to the regulation voltage. When the bat-
tery voltage is above the regulation voltage, the LDO
regulator controls the output voltage.
For high input voltages, if the power is applied abruptly,
the MAIN output capacitor charges quickly, causing
the L2 inductor current to rise above the 2A current
limit. To prevent damage to the MAX1800, diode D10 is
used to charge main output capacitor C17, preventing
excessive current in the inductor. Components R46,
C24, and D9 delay turn-on of the MAIN converter when
power is applied. This prevents damage to the switch-
es caused by switching with excessive inductor current
at turn-on. If the MAX1800 is used exclusively with low
input voltage, components R46, C24, D9, and D10 may
be omitted.
High Input Voltage Operation
_______________________________________________________________________________________
MAX1800 Evaluation Kit
Note: Please indicate that you are using the MAX1800/
MAX1801 when contacting these suppliers.
AVX
Central
Semiconductor
Fairchild
Semiconductor
Motorola
Sumida
Taiyo Yuden
TDK
SUPPLIER
Component Suppliers
803-946-0690
631-435-1110
408-721-2181
602-303-5454
847-956-0666
408-573-4150
847-803-6100
PHONE
803-626-3123
631-435-1824
408-721-1635
602-994-6430
847-956-0702
408-573-4159
847-803-6296
FAX
5