LTC1479 datasheet(4/24 Pages) LINER

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LTC1479

AC ELECTRICAL CHARACTERISTICS

VDCIN = 25V, VBAT1 = 16V, VBAT2 = 12V, TA = 25°C unless otherwise noted. (Note 2)

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

tONGA/GB

Gate A/B Turn-On Time

VGS > 3V (Note 5)

µs

tONGC/GD

Gate C/D Turn-On Time

VGS > 3V (Note 5)

µs

tONGE/GF

Gate E/F Turn-On Time

VGS > 3V (Note 5)

µs

tOFFGA/GB

Gate A/B Turn-Off Time

VGS < 1V (Note 5)

µs

tOFFGC/GD

Gate C/D Turn-Off Time

VGS < 1V (Note 5)

µs

tOFFGE/GF

Gate E/F Turn-Off Time

VGS < 1V (Note 5)

µs

tONGG/GH

Gate G/H Turn-On Time

VGS > 3V (Note 5)

300

µs

tOFFGG/GH

Gate G/H Turn-Off Time

VGS < 1V (Note 5)

µs

fOVGG

VGG Reg Operating Frequency

kHz

tdLOBAT

LOBAT Delay Times

∆VBDIV = ±100mV, RPULLUP = 51k

µs

tdDCINGOOD

DCINGOOD Delay Times

∆VDCDIV = ±100mV, RPULLUP = 51k

µs

The q 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 VCCP or VCC 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 2

µA 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., VSENSE = 0V, using Si4936DY MOSFETs in the typical

application circuit.

TRUTH TABLE

SELECTED MODES

LOGIC INPUTS

SWITCH STATUS

OUTPUTS

NO. MODE

3DM DCIN/BAT BATSEL

BATDIS

CHGSEL

A/B

C/D

E/F

CHGMON

VBAT LOBAT DCINGOOD

DC Operation

Off

Hi-Z

BAT1

DC Operation and

Off

BAT1

BAT1 Charging

DC Operation and

Off

Hi-Z

BAT2

BAT2 Disconnected

DC Operation and

Off

BAT2

BAT2 Charging

BAT1 Operation

Off

Hi-Z

BAT1

BAT2 Operation

Off

Hi-Z

BAT2

BAT1 Low and

Off

Hi-Z

BAT1

Disconnected

Backup Operation

Off

Hi-Z

BAT1

No Power

Off

Hi-Z

BAT2

(No Backup)

10 DC Reconnected

3DM* 3DM* 3DM* Off

Off

Hi-Z

BAT1

11 DC Connected

Off

Hi-Z

BAT1

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.

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