8
Rev. 0
EVALUATE USB CHARGER PROFILES
The LT8698S/LT8698S-1 supports several common USB
charger profiles, and the DC2688A demo board is easy to
set up to evaluate these common charger profiles.
Refer to Figure 9 for proper measurement equipment
setup and follow the procedure below.
1. Check that JP6 and JP7 are placed on the OFF posi-
tion, to ensure that the on-board LDOs are disabled.
2. Select JP2, JP3, and JP4 jumpers at appropriate
locations based on the desired charger profile and
SEL pin lookup table in the LT8698S/LT8698S-1 data
sheet. Table 1 shows several popular USB charger
profiles available in the LT8698S/LT8698S-1. Refer
to LT8698S/LT8698S-1 data sheet for further infor-
mation about USB charger profiles.
3. With power off, connect the input power supply to
V
EMI
and GND turrets. If the EMI/EMC performance
is not important, connect the input power supply to
VIN and GND turrets.
4. Check that JP1 EN jumper is placed on the ON position.
QUICK START PROCEDURE
5. Turn on the power at the input.
NOTE:
Make sure that the input voltage never
exceeds 42V.
6. Check for proper output voltages: V
BUS
= 5V, and D11
LED indicator lights up in green.
7. Attach a portable device to the type A socket of the
DC2688A demo board.
8. Observe the battery charging activity on the
portable device.
9. Observe charging current by measuring the voltage
on IMON turret: the IMON voltage should be equal to
0.46V/A in proportion to the I
BUS
load current.
Table 1. Common USB Charger Profiles and Corresponding
SEL Pins
SEL1
SEL2
SEL3 CHARGER PROFILE DESCRIPTION
State 21
LOW
TRI
HIGH USB BC 1.2 DCP Profile
State 22
TRI
TRI
HIGH 2.0A Vendor Charger Profile
State 24
LOW
HIGH
HIGH 2.4A Vendor Charger Profile
