Datasheet
4
LTC1479
AC ELECTRICAL CHARACTERISTICS
V
DCIN
= 25V, V
BAT1
= 16V, V
BAT2
= 12V, T
A
= 25°C unless otherwise noted. (Note 2)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
t
ONGA/GB
Gate A/B Turn-On Time V
GS
> 3V (Note 5) 30 µs
t
ONGC/GD
Gate C/D Turn-On Time V
GS
> 3V (Note 5) 30 µs
t
ONGE/GF
Gate E/F Turn-On Time V
GS
> 3V (Note 5) 30 µs
t
OFFGA/GB
Gate A/B Turn-Off Time V
GS
< 1V (Note 5) 3 µs
t
OFFGC/GD
Gate C/D Turn-Off Time V
GS
< 1V (Note 5) 3 µs
t
OFFGE/GF
Gate E/F Turn-Off Time V
GS
< 1V (Note 5) 3 µs
t
ONGG/GH
Gate G/H Turn-On Time V
GS
> 3V (Note 5) 300 µs
t
OFFGG/GH
Gate G/H Turn-Off Time V
GS
< 1V (Note 5) 5 µs
f
OVGG
V
GG
Reg Operating Frequency 30 kHz
t
dLOBAT
LOBAT Delay Times ∆V
BDIV
= ±100mV, R
PULLUP
= 51k 5 µs
t
dDCINGOOD
DCINGOOD Delay Times ∆V
DCDIV
= ±100mV, R
PULLUP
= 51k 5 µs
The ● denotes specifications which apply over the full operating
temperature range.
Note 1: The logic inputs are high impedance CMOS gates with ESD
protection diodes to ground and therefore should not be forced below
ground. These inputs can however be driven above the V
CCP
or V
CC
supply
rails as there are no clamping diodes connected between the input pins
and the supply rails. This facilitates operation in mixed 5V/3V systems.
Note 2: The Selected Operating Mode Truth Table, which defines the
operating conditions and logical states associated with each “normal”
operating mode, should be used in conjunction with the Electrical
Characteristics table to establish test conditions. Actual production test
conditions may be more stringent.
Note 3: The following inputs are high impedance CMOS inputs:
3DM and DCIN/BAT and have no internal pull-up current.
Note 4: The following inputs have built-in 2µA pull-up current sources
(passed through series diodes): BATSEL, BATDIS and CHGSEL.
Note 5: Gate turn-on and turn-off times are measured with no inrush
current limiting, i. e., V
SENSE
= 0V, using Si4936DY MOSFETs in the typical
application circuit.
TRUTH TABLE
SELECTED MODES LOGIC INPUTS SWITCH STATUS OUTPUTS
SW SW SW SW SW
NO. MODE 3DM DCIN/BAT BATSEL BATDIS CHGSEL A/B C/D E/F G H CHGMON V
BAT
LOBAT DCINGOOD
1 DC Operation H H H L H On Off Off Off Off Hi-Z BAT1 H H
2 DC Operation and H H H H H On Off Off On Off BAT1 BAT1 H H
BAT1 Charging
3 DC Operation and H H L L L On Off Off Off Off Hi-Z BAT2 H H
BAT2 Disconnected
4 DC Operation and H H L H L On Off Off Off On BAT2 BAT2 H H
BAT2 Charging
5 BAT1 Operation H L H H H Off On Off Off Off Hi-Z BAT1 H L
6 BAT2 Operation H L L H H Off Off On Off Off Hi-Z BAT2 H L
7 BAT1 Low and H L H L H Off Off Off Off Off Hi-Z BAT1 L L
Disconnected
8 Backup Operation H L H L H Off Off Off Off Off Hi-Z BAT1 L L
9 No Power L L L L L Off Off Off Off Off Hi-Z BAT2 L L
(No Backup)
10 DC Reconnected L L H L H 3DM* 3DM* 3DM* Off Off Hi-Z BAT1 L H
11 DC Connected H H H L H On Off Off Off Off Hi-Z BAT1 L H
and Reset
(Selected Operating Modes)
* 3DM = Three Diode Mode. When this mode is invoked, only the first
MOSFET switch in each back-to-back switch pair, i. e., SW A, SW C and
SW E is turned on. Current may still pass through the inherent body
diode of the idled switches, i.e., SW B, SW D and SW F to help restart
the system after abnormal operating conditions have been encountered.
See the Timing Diagram and Applications Information sections for
further details.