Linear Technology Analog Devices LT8708, Datasheet

Page: 60 / 64

LT8708
60
Rev 0
For more information www.analog.com
APPLICATIONS INFORMATION
Transient Behavior Upon V
IN
Dropout, V
BAT
= 52V
Transient Behavior Upon V
IN
Dropout, V
BAT
= 53V
Transient Behavior Upon V
IN
Dropout, V
BAT
= 38V
52V Battery Backup Supply Using FHCM and RHCM Detail
Table of Operation Modes and Power Flow Directions
CONDITIONS RESULTS
V
LOAD
V
BAT
POWER FLOW CHIP OPERATES IN RVSOFF DIR
– <V
BAT_DEAD
No Power Flow Shutdown – –
>50.2V*
>52.1V
V
BAT_DEAD
to 52.1V
Power Flows from V
IN
to V
BAT
(V
BAT
Charging)
FHCM Lo Hi
Fell Into (47.4V to 50.2V) Range*
>52.1V
No Power Flow Fell Into (45.9V to 47.4V) Range*
>V
BAT_DEAD
Rose Into (47.4V to 50.2V) Range*
RHCM Hi Lo Rose Into (45.9V to 47.4V) Range
Power Flows from V
BAT
to V
LOAD
(Backup Operation)
<45.9V
*V
LOAD
is powered from V
IN
.
V
BAT
Charge Voltage = 52.1V (FBOUT in FHCM) V
LOAD
Rising to Activate V
BAT
Charging = 50.2V (VINHIMON Rising Activating FHCM)
V
LOAD
Regulation Voltage = 47.4V (FBIN in RHCM) V
LOAD
Falling to Activate Backup Operation = 45.9V (VINHIMON Falling Activating RHCM)
V
BAT_DEAD
= 36V (Falling) or 37.5V (Rising) V
BAT
Charging Current Limit = 5A (IMON_OP)
Frequency = 150kHz V
LOAD
Current Limit = 5A (IMON_INN)
3ms/DIV
8708 TA05d
DIR 5V/DIV
V
LOAD
5V/DIV
V
IN
5V/DIV
I
L
5A/DIV
3ms/DIV
8708 TA05e
DIR 5V/DIV
V
LOAD
5V/DIV
V
IN
5V/DIV
I
L
10A/DIV
3ms/DIV
8708 TA05f
DIR 5V/DIV
V
LOAD
5V/DIV
V
IN
5V/DIV
I
L
5A/DIV