Analog Devices EVAL-LT8624S-AZ-IBB User Manual

General Description
The EVAL-LT8624S-AZ-IBB demonstration board is the
inverting buck-boost topology version of the LT8624S, an
18V, 4A synchronous Silent Switcher
regulator with ultra-low noise, high efficiency, and power
density. The input voltage range of the EVAL-LT8624S-
AZ-IBB is 2.7V to (18V - |V
setting is -5V for a 2A maximum DC output current with a
5V input, or a 4A maximum DC output current with a 12V
input. The LT8624S is a compact, ultra-low noise, ultra-low
emission, high efficiency, and high-speed synchronous
monolithic step-down switching regulator used as an
inverting buck-boost converter. The uniquely designed
combination of the ultra-low noise reference and third-
generation Silent Switcher architecture enables the
LT8624S to achieve both high efficiency and excellent
wideband noise performance. A minimum on-time of 12ns
allows high V to low V
IN OUT
The LT8624S switching frequency can be programmed
either through an external resistor RT, or an external clock
over a 300kHz to 6MHz range. The default frequency of
EVAL-LT8624S-AZ-IBB demo board is 2MHz. The SYNC
pin on the demo board is connected to -V
mode operation. To synchronize to an external clock,
move JP1 to SYNC and apply the external clock to the
SYNC terminal. Select the forced continuous mode (FCM)
by moving the JP1 shunt respectively.
efficiency of the circuit at 5V input and 12V input in the
Rev A
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 .
LT8624S 18V, 4A Synchronous Step-Down Silent Switcher
with Ultra-Low Noise Reference Used as an IBB Converter
®
3 step-down
|). The default demo board
OUT
conversion at high frequency.
for pulse-skip
OUT
Figure 1 shows the
Evaluation Board User Guide
EVAL-LT8624S-AZ-IBB
FCM operation (input from VIN terminal).
the LT8624S temperature rising on the EVAL-LT8624S-
AZ-IBB demo board under 1A, 2A, and 3A load conditions,
for the full input voltage range. The case temperature rise
was measured with the following reference points: The
peak IC case temperature and a point on the board,
marked with a red 'X' as shown in the thermal picture in
Figure 7.
The demo board has an electromagnetic interference
(EMI) filter installed by default between V
the IC. The EMI performance of the board is shown in
Figure 3. The red line in Radiated EMI Performance is the
CISPR32 Class B limit. In addition to the excellent EMI
performance, the regulator also features ultra-low noise
over a wide frequency range, as is shown in
The LT8622S/LT8624S data sheet gives a complete
description of the LT8624S part, including operation and
application information. Read the data sheet in conjunction
with this demo manual for LT8624S-AZ-IBB demo board.
The LT8624S is assembled in a 4mm x 3mm LQFN
package with exposed ground pads for low thermal
resistance. The layout recommendations for low EMI
operation and maximum thermal performance are
available in the LT8622S/LT8624S data sheet section
'PCB Layout Recommendations.'
Design files for this circuit board are available in the
Design Center at www.analog.com.
DOCUMENT FEEDBACK
T e l : 7 8 1 . 3 2 9 . 4 7 0 0 © 2 0 2 4 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 .
Figure 2 shows
terminal and
IN
Figure 4.
TECHNICAL SUPPORT