MAX1677EVKIT Maxim Integrated, MAX1677EVKIT Datasheet - Page 3

• Manufacturer Part Number: MAX1677EVKIT
• Description: Power Management IC Development Tools Evaluation Kit for the MAX1677
• Manufacturer: Maxim Integrated
• Series: MAX1677r

Specifications of MAX1677EVKIT

• Output Voltage: 3.3 V, +/- 28 V
• Output Current: 350 mA

The main boost converter has three operational modes:
a low-power PFM mode; a high-power, low-noise PWM
mode; and a high-power PWM mode with the internal
oscillator synchronized to an external clock. The EV kit
operates at 300kHz switching frequency and allows the
use of small inductor values. The switching frequency
can also be synchronized to an external clock ranging
from 200kHz to 400kHz. The 3-pin headers JU3 and
JU6 select the operating mode for each circuit. Table 3
lists the jumper options.
Table 3. Jumper JU3/JU6 Functions
LOCATION
SHUNT
Open
1 & 2
2 & 3
Connected to GND
Connected to V
CLK/SEL connect-
ed to CLK/SEL pad
CLK/SEL PIN
_______________________________________________________________________________________
OUT
Low-power mode,
MAX1677 operates in the
PFM mode.
High-power, low-noise
mode, MAX1677 operates
in the PWM mode.
Synchronized PWM high-
power mode, CLK/SEL
pin is driven by an exter-
nal clock between 200kHz
and 400kHz.
OPERATING MODE
Operating Mode
MAX1677 Evaluation Kit
The main output is set to +3.3V by grounding the feed-
back pins (FB) via PC traces shorting R2 and R10. To
generate main output voltages other than +3.3V (+2.5V
to +5.5V), cut the traces across R2 and R10 and select
the external voltage divider resistors (R1, R2 or R9, and
R10). Refer to Design Procedure section in the
MAX1677 data sheet for instructions on selecting R1,
R2 and R9, and R10.
The ±20V LCD bias output voltages are set with voltage
dividers (R3, R4 or R11, and R12) at the LCD feedback
pins (LCDFB). To generate LCD output voltages other
than ±20V, refer to Setting the LCD Output Voltage sec-
tion in the MAX1677 data sheet.
The LCD inductor current limit can be set to 225mA or
350mA. The EV kit is factory-configured for 350mA. To
set the limit to 225mA, cut the PC trace shorting R17 or
R18 and insert a 56kΩ resistor. This allows the use of
the smallest possible inductors for low-current displays.
See the LCD Boost Converter section of the MAX1677
data sheet for more information.
Evaluating Other Output Voltages
Changing the LCD Current Limit
3