Analog Devices Linear ADI Power SCP-LT8618-BEVALZ Quick setup guide

DEMO MANUAL SCP-LT8618-BEVALZ
Rev. 0
1
DESCRIPTION
Demonstration circuit SCP-LT8618-BEVALZ is a high effi-
ciency 60V, 1 0 0 m A s y n c h r o n o u s s t e p -down regulator. The
wide input range also allows output voltage inversion by
using the SCP-LT8618-IEVALZ version of this board.
Like all boards in the Signal Chain Power series, this board
is designed to be easily plugged into other SCP boards to
form a complete signal chain power system, enabling fast
evaluation of low power signal chains. To evaluate this
board, some universal SCP hardware is required, namely:
SCP-INPUT-EVALZ SCP-FILTER-EVALZ
SCP-OUTPUT-EVALZ SCP-1X2BKOUT-EVALZ
SCP-1X5BKOUT-EVALZ SCP-5X1-EVALZ
SCP-THRUBRD-EVALZ
To properly evaluate SCP series demo boards, you will
need the SCP Configurator companion software. SCP
Configurator can help you choose the right board and to-
pology for your design.
Note that this Demo Manual does not cover details im-
portant to the operation and configuration regarding the
LT8618. Please refer to the LT 8 6 1 8 d a t a s h e e t for a com-
plete description of the part.
Design files for this circuit board are available.
All registered trademarks and trademarks are property of their respective owners.
Table 1. Performance Summary
SYMBOL
PARAMETER
NOTES
MIN
TYP
MAX
UNITS
V
IN(MAX)
Max Input Voltage
60
V
V
OUT(MAX)
Max Output Voltage
48
V
I
OUT(MAX)
Max Output Current
100
mA
BOARD IMAGE
Figure 1. SCP-LT 8 6 1 8 -BEVALZ Evaluation Board
DEMO MANUAL
SCP-LT8618-BEVALZ
Signal Chain Power Series
LT8618 High Efficiency
Synchronous Buck Converter

DEMO MANUAL SCP-LT8618-BEVALZ
Rev. 0
2
QUICK START PROCEDURE
Demonstration circuit SCP-LT8618-BEVALZ is easy to
set up to evaluate the performance of any SCP hard-
ware configuration.
1. The SCP-LT8618-BEVALZ ships with a default output
voltage of 5V. To change the output voltage, see “Con-
figuration Settings” section, and modify the board ac-
cordingly. Be sure to check for open connections or sol-
der shorts after making any modifications.
2. Connect the SCP-INPUT-EVALZ and SCP-OUTPUT-
EVALZ boards to the SCP-LT8618-BEVALZ (refer to Fig-
ure 2) and connect the input board to a voltage source,
V
SOURCE
. Connect the output board to a voltmeter or
dynamic load. Slowly raise the input voltage until the
SCP-LT8618-BEVALZ powers up into regulation and
sweep V
SOURCE
through the desired range of operation.
NOTE: Make sure that the input voltage is always within
spec. If using a dynamic load to measure output volt-
age, make sure the load is initially set to zero.
3. Check for proper output voltage. The output should be
regulated at the programmed value (±5%).
4. Once the proper output voltage is established, power
off V
SOURCE
and similarly test other boards in the SCP
system until all elements have been individually verified
prior to assembling into the final circuit configuration.
NOTE: When measuring the input or output voltage rip-
ple, use the optional SMA connector locations available
on the input, output, 1 ´ 5, 1 ´ 2, and 5 ´ 1 breakout
boards. Avoid using the test point connections with
long scope leads.
Figure 2. Proper Measurement Equipment Setup (Use SMA connectors for Measuring Input or Output Ripple)

DEMO MANUAL SCP-LT8618-BEVALZ
Rev. 0
3
CONFIGURATION SETTINGS
Demonstration circuit SCP-LT8618-BEVALZ is a high effi-
ciency 65V, 100mA synchronous step-down regulator. The
wide input range also allows output voltage inversion by
using the SCP-LT8618-IEVALZ version of this board.
The output of the SCP-LT8618-BEVALZ is resistor-pro-
grammable from 0.8V to 48V. T h e b o a r d c a n b e also con-
figured to drive VIOC-capable linear regulators.
OUTPUT VOLTA G E PROGRAMMING
!
Table 2. Resistor Selection Guide for Common Output Voltages
V
OUT
(V)
R4 (Ω)
R5 (Ω)
0.8
3.24k
115k
0.9
3.83k
137k
1.0
102k
357k
1.1
42.2k
102k
1.2
102k
187k
1.25
162k
267k
1.5
205k
221k
1.8
1.00M
768k
2.0
1.15M
732k
2.5
1.47M
665k
3.0
1.02M
357k
3.3
590k
182k
3.5
357k
102k
4.0
422k
102k
4.5
511k
107k
5.0
1.02M
187k
5.5
698k
115k
6.0
1.13M
169k
6.5
787k
107k
7.0
1.50M
187k
7.5
1.27M
147k
8.0
1.30M
140k
12.0
1.47M
102k
16.0
1.50M
76.8k
20.0
1.50M
60.4k
24.0
1.50M
49.9k
30.0
1.50M
40.2k
36.0
1.50M
33.2k
42.0
1.50M
28.0k
48.0
1.50M
24.9k
EN/UV PIN CONFIGURATION
The EN/UV pin is tied to the optional SCP Run/Sequence
header P1. To create a harness for this function, use Molex
part 0510650300 with crimp pin 50212-8000.
To use an active run signal, use a 1.00M resistor for either
pull-up or pull-down resistors R1 and R6, short R11 with
0 W , and use the drive signal from connector P1. Also,
short R12 with 0 W for output voltage monitoring.
If precision UVLO operation is desired, program enable di-
vider R1 and R6 such that:
R6 is 10k to 100k, nominal
!
The LT8618 has an accurate 1.05V threshold which places
the part into under voltage lockout. The hysteresis thresh-
old on the rising edge is typically 50mV and scales by the
factor:
!
VOLTAGE INPUT-TO-OUTPUT CONTROL (VIOC)
IMPLEMENTATION
To implement the VIOC function for this regulator, set R8
and R13 to 0 W , respectively. Refer to the “Configuration
Settings” section in the Demo Manual for the low-dropout
(LDO) linear regulator board and use the following config-
uration for this board.
Table 3. VIOC Cross-Reference Designators
VIOC SETTING REFERENCES
R
BOT
R
TOP
R
MAX
V
OUT
Reference Designators
R5
R4
R7
!
I
SINK
is the current through R
MAX
, typically 15µA, so R
BOT
should be sized such that the divider current runs a mini-
mum of 100µA to minimize the I
SINK
error term.
VOUT =0 .7 7 8 V 1 +R4
R5
⎛
⎝
⎜⎞
⎠
⎟
R1 =R6 VIN −1 .0 5 V
1 .0 5 V
⎛
⎝
⎜⎞
⎠
⎟
VHYST =50mV R1+R6
R6
VL DOIN −VL DOOUT =VVIOC =0 .7 7 8 V RBOT +RTOP
RBOT
⎛
⎝
⎜⎞
⎠
⎟
VMAX
( )
LDOIN =0 .7 7 8 V RBOT +RTOP +RMAX
RBOT
⎛
⎝
⎜⎞
⎠
⎟+ISINKRMAX

DEMO MANUAL SCP-LT8618-BEVALZ
Rev. 0
4
FREQUENCY PIN CONFIGURATION
The LT8618 allows the user to program an operating fre-
quency by a single resistor. The default operating fre-
quency is 2.0MHz. Note that changing the switching fre-
quency may affect other parameters and likely necessi-
tates a change in inductor and compensation component
values. Contact the SCP team for applications support if
shifting the switching frequency greater than ±10%.
Table 4. Resistor Selection Guide for Switching Frequency Setting
f
SW
R
2
(Ω)
f
SW
R
2
(Ω)
200kHz
221k
1.30MHz
30.1k
300kHz
143k
1.40MHz
27.4k
400kHz
110k
1.50MHz
25.5k
500kHz
86.6k
1.60MHz
23.7k
600kHz
71.5k
1.70MHz
22.1k
700kHz
60.4k
1.80MHz
20.5k
800kHz
52.3k
1.90MHz
19.1k
900kHz
46.4k
2.00MHz
18.2k
1.00MHz
40.2k
2.10MHz
16.9k
1.10MHz
36.5k
2.20MHz
16.2k
1.20MHz
33.2k

DEMO MANUAL SCP-LT8618-BEVALZ
Rev. 0
5
PARTS LIST
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
1
1
PCB
PRINTED CIRCUIT BOARD
ANALOG DEVICES 08_059761a
2
1
C1
CAP 22uF 63V ALUM 8x10.5
SUN ELECTRONIC 63CE22BSA
3
1
C2
CAP 1uF 100V CER, X7R 1206
TAIYO YUDEN HMK316B7105KL-T
4
1
C3
CAP 0.1uF 100V CER X7R 0603
SAMSUNG CL10B104KC8NNNC
5
1
C4
CAP 47nF 50V CER X7R 0603
KEMET C0603X473K5RACTU
6
1
C5
CAP MLCC 0603 (Note 1)
N/A
7
1
C6
CAP 10uF 50V X5R 1206
SAMSUNG CL31A106MBHNNNE
8
1
C7
CAP 1uF 10V X7R 0603
SAMSUNG CL10B105KP8NNNC
9
1
C8
CAP 10nF 50V CER X7R 0603
YAGEO CC0603KRX7R9BB103
10
1
C9
CAP 4.7uF 50V CER X7R 1206
SAMSUNG CL31B475KBHNNNE
11
1
INPUT
CONN MALE 3POS 2.54MM PITCH R/A
SULLINS PBC03SBAN
12
1
L1
IND 33uH 0.42A 0.66OHM
WURTH ELEKTRONIK 44031330
13
1
OUTPUT
CONN FEMALE 3POS 2.54MM PITCH R/A
SULLINS PPPC031LGBN-RC
14
1
P1
CONN-PCB 3POS HEADER WIRE TO BRD WAFER ASSY
STRAIGHT 2MM PITCH (Note 1)
MOLEX 53253-0370
15
1
R1
RES 1M 1%THICK FILM 0805
YAGEO RC0805JR-071ML
16
6
R6, R8, R10,
R11, R12, R13
RED THICK FILM 0805 (Note 1)
N/A
17
3
R14, R15, R16
RES 0 OHM 1% 3/4W 0612
VISHAY RCL06120000Z0EA
18
2
R17, R18
RES THICK FILM 0612 (Note 1)
N/A
19
1
R2
RES 18.2K 1% THICK FILM 0805
PANASONIC ERJ-6ENF1822V
20
1
R3
RES 49.9K 1% THICK FILM 0805
PANASONIC ERJ-3EKF4992V
21
1
R4
RES 1M 1% THICK FILM 0805
PANASONIC ERJ-6ENF1004V
22
1
R5
RES 187K 1% THICK FILM 0805
PANASONIC ERJ-6ENF1873V
23
2
R7, R9
RES 0-OHM 1%THICK FILM 0805
VISHAY CRCW08050000Z0EA
24
1
U1
IC-ADI HIGH EFFICIENCY 60V/100MA SYNCHRONOUS BUCK
ANALOG DEVICES LT 8 6 1 8 E D D B # P B F
25
1
VIOC
CONN FEMALE 2POS 2.54MM PITCH R/A
SULLINS PPPC021LGBN-RC
Note 1. These items are not stuffed (DNI).

DEMO MANUAL SCP-LT8618-BEVALZ
Rev. 0
6
SCHEMATIC DIAGRAM
LT8618 BUCK
22UF 0.1UF
100V
DNI
0.047UF
10UF
49.9K
0
0
50V
DNI
DNI
4.7UF
50V
33UH
10V
DNI
50V
0.01UF
187K
18.2K
50V
LT8618EDDB#PBF
1MEG
DNI
63V
PPPC021LGBN-RC
PBC03SBAN
1UF
0
PPPC031LGBN-RC
53253-0370
DNI
DNI 1UF
DNI
DNI
0
0
DNI
1MEG
100V
A SERQUINA
02_059761 A
1:1
HW TYPE : Customer Evaluation
Product(s): LT8618
: LT8618
<DESIGN_VIEW>
22
PG
C3
R11
C1
U1
R1
C2
C8C7
L1
R5
C4
C6 C9
INPUT
OUTPUT VIOC
R7
P1
C5
R4
R3
R2
R18
R17
R14
R12 R13
R10
R8
R16
R9
R15
R6
PG
VPOS
BIAS
VIOC
PG
VNEG
RUN
VNEG
V+
VO-
VO+
RUN
GND
VO+
VNEG
VIOC
VO- GND
GND
BIAS
PAD
P
2
N
3
1
9
6
4
85
7
10
1 2 31
2 3 1 2
1 2 3
GND
EN/UV VIN
PG
TR/SS
FB/OUT
BIAS RT INTVCC
SW
BST
D
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DEMO MANUAL SCP-LT8618-BEVALZ
Rev. 0
7
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Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications
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DEMO MANUAL SCP-LT8618-BEVALZ
Rev. 0
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circuitry, damage may occur on devices subjected to high energy ESD. Therefore, proper ESD precautions should be taken to avoid performance degradation or loss of functionality.
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