Analog Devices EVAL-LT8277-AZ User Manual

General Description
Evaluation circuit EVAL-LT8277-AZ is a dual-phase non-
synchronous high-power step-up converter featuring the
LT8277. It regulates the output voltage up to 60V and
drives up to a 3A load at 60V when the V
and 36V. The EVAL-LT8277-AZ runs at 200kHz switching
frequency with the ability to turn on spread spectrum
frequency modulation (SSFM) for reduced EMI emission.
It can run with or without SPI communications. Multiple
EVAL-LT8277-AZ can be paralleled to deliver more output
power. A graphic user interface (GUI) is available when
connected to a DC2026C Linduino One demo circuit.
The LT8277 is a dual-phase interleaved current mode
boost and SEPIC controller. It has a wide input voltage
range from 3V to 40V and an adjustable switching
frequency between 100kHz and 2MHz. The EVAL-
LT8277-AZ enables users to easily evaluate LT8277's
features, like the SPI interface, PGOOD output status
reporting, frequency synchronization, clock output for 4- or
8-phase operation, etc. Users could change the R
to set the circuit's switching frequency, change ENABLE
resistors to set the minimum input voltage when the circuit
starts operation and change V
loop compensation.
With SPI control, EVAL-LT8277-AZ can set the output
voltage from 9V to 60V in a 0.5V step. The SPI interface
also configures on/off of the clock output (CLKOUT pin),
clock output phase shift, speed of soft start, and keep/drop
Performance Summary (T
PARAMETER
Input Voltage PV Range
IN
Switching Frequency
Output Voltage Range V
OUT
Max. Output Current I
OUT
PV Undervoltage Lockout
IN
(Falling)
PV Turn-On Voltage (Rising)
IN
Efficiency
Rev.0
O n e A n a l o g W a y , W i l m i n g t o n , M A 0 1 8 8 7 - 2 3 5 6 , U . S . A .
is between 9V
IN
resistor
T
pin components to adjust
C
= 25°C)
A
CONDITIONS
Operating
R8 = 200kΩ
Set by SPI Interface
V = 9V, V = 60V
IN OUT
R9 = 383kΩ, R12 = 82.5kΩ
R9 = 383kΩ, R12 = 82.5kΩ
V = 12V, V = 60V, I
IN OUT
DOCUMENT FEEDBACK
T e l : 7 8 1 . 3 2 9 . 4 7 0 0
Evaluation Board User Guide
EVAL-LT8277-AZ
High Power Multiphase Step-Up Controller
phase two at light load conditions. The MODE pin controls
the watchdog timer of the SPI interface. The JP3 jumper
sets the MODE pin voltage or enables GUI control of the
MODE pin. For a detailed way of using the SPI interface
and MODE pin, refer to the EVAL-LT8277-AZ GUI manual.
The EVAL-LT8277-AZ features an input EMI filter for low
emissions. Inductor current is sensed by sensing resistors,
while DCR sensing is available. Power-stage MOSFETs
and diodes are optimized to achieve high efficiency. The
PCB has large copper planes and extensive vias for
excellent high-power thermal performance.
The LT8277 data sheet gives a complete description of the
device, operation, and applications information. The data
sheet must be read in conjunction with this user guide for
EVAL-LT8277-AZ.
assembled in a 3mm x 4mm, Plastic Side-solderable QFN
package with a thermally enhanced ground pad. A proper
board layout is essential
performance. Refer to the data sheet layout considerations
section.
Windows ® -based graphical user interface (GUI) software
is available for use with the EV kit and can be downloaded
from the LT8277 website. Follow the EVAL-LT8277-AZ
GUI manual for software installation and evaluation
guidance.
Design files for this circuit board are available at
www.analog.com.
MIN
9
9
= 3A
OUT
© 2 0 2 3 A n a l o g D e v i c e s , I n c . A l l r i g h t s r e s e r v e d .
The LT8277RUDCM#WPBF
for maximum
TYP MAX
36
200
60
3
7.1
8.4
92
TECHNICAL SUPPORT
is
thermal
UNITS
V
kHz
V
A
V
V
%