Configuration Settings - Analog Devices Linear SCP-LT8362-S-EVALZ Demo Manual

CONFIGURATION SETTINGS

Demonstration circuit SCP-LT8362-S-EVALZ features the
LT8362 in a SEPIC configuration. It operates with a switch-
ing frequency of 2MHz and has an output voltage of 12V.
The output of the SCP-LT8362-B-EVALZ is resistor-pro-
grammable from 5V to 48V. The board can be also config-
ured to drive VIOC-capable LDO regulators.
OUTPUT VOLTAGE PROGRAMMING
⎛ ⎞
R6
= 1 .6 V 1 +
V ⎝ ⎜ ⎠ ⎟
OUT FBX
R8
Table 2. Resistor Selection Guide for Common Output Voltages
V (V)
OUT
5.0
6.0
7.0
8.0
9.0
10.0
11.0
12.0
13.0
14.0
15.0
16.0
17.0
18.0
19.0
20.0
21.0
22.0
23.0
24.0
25.0
30.0
35.0
40.0
45.0
48.0
DEMO MANUAL SCP-LT8362-S-EVALZ
R6 (Ω) R8 (Ω)
24.3K 11.5K
31.6K 11.5K
115K 34.0K
102K 25.5K
118K 25.5K
105K 20.0K
107K 18.2K
71.5K 11.0K
97.6K 13.7K
78.7K 10.2K
115K 13.7K
102K 11.3K
162K 16.9K
205K 20.0K
150K 13.7K
115K 10.0K
243K 20.0K
255K 20.0K
226K 16.9K
140K 10.0K
215K 14.7K
442K 24.9K
287K 13.7K
255K 10.7K
374K 13.7K
309K 10.7K
EN/UVLO PIN CONFIGURATION
The EN/UVLO pin is tied to the optional SCP Run/Se-
quence 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 for either pull-up
or pull-down resistors R1 and R3, short R13 with 0W, and
use the drive signal from connector P1.
If precision UVLO operation is desired, program enable di-
vider R5 and R6 such that:
R6 = 1 0 k − 1 0 0 k, n o min al
⎛ − 1 .6 0 V ⎞
V
IN TH
R5 = R6
⎝ ⎜ ⎠ ⎟
1 .6 0 V
TH
The LT8330 has an accurate 1.60V threshold which places
the part into under voltage lockout. The hysteresis thresh-
old on the rising edge is typically 80mV and scales by the
factor:
R5 + R6
⎛ ⎞
V = 80mV
⎝ ⎜ ⎠ ⎟
HYST
R6
VOLTAGE INPUT-TO-OUTPUT CONTROL (VIOC)
IMPLEMENTATION
To implement the VIOC function for this regulator, set R27
to 0W. Refer to the "Configuration Settings" section in the
Demo Manual for the LDO board and use the following
configuration for this board.
Table 3. VIOC Cross-Reference Designators
VIOC SETTING REFERENCES
V Reference Designators
OUT
− V = V = 1 .6 0 V
V
L DOIN L DOOUT VIOC
⎛
R
BOT
= 1 .6 0 V
V
( )
FB ⎝ ⎜
MAX LDOIN
I is the current through R
SINK
should be sized such that the divider current runs a mini-
mum of 100µA to minimize the I
R R R
BOT TOP
R8 R6 R14
⎛ ⎞
R + R
BOT TOP
FB ⎝ ⎜ ⎠ ⎟
R
BOT
⎞
+ R + R
TOP MAX
+ I
R
⎠ ⎟ MAX
SINK
R
BOT
, typically 15µA, so R
MAX
error term.
SINK
MAX
BOT
Rev. 0
3