LTC7803 datasheet(6/42 Pages) AD

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LTC7811

Rev. 0

For more information www.analog.com

ELECTRICAL CHARACTERISTICS The

indicates specifications which apply over the specified operating

junction temperature range, otherwise specifications are for TA = 25°C, VBIAS = 12V, RUN1,2,3>1.25V, EXTVCC = 0V, VPRG3 = FLOAT

unless otherwise noted. (Note 2)

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

PLLIN Input High Level

PLLIN Input Low Level

2.2

0.5

Spread Spectrum Frequency Range

(Relative to fOSC)

PLLIN/SPREAD = INTVCC

Minimum Frequency

Maximum Frequency

–12

+15

PGOOD1 and BATTGOOD Outputs

PGOOD1 Voltage Low

IPGOOD1 = 2mA

0.2

0.4

PGOOD1 Leakage Current

VPGOOD1 = 5V

±1

µA

PGOOD1 Trip Level

VFB1 Relative to Set Regulation Point

VFB1 Rising

Hysteresis

2.5

VFB1 Falling

Hysteresis

–13

–10

2.5

–7

PGOOD1 Delay for Reporting a Fault

µs

BATTGOOD Voltage Low

IBATTGOOD = 2mA

0.2

0.4

BATTGOOD Leakage Current

VBATTGOOD = 5V

±1

µA

Battery Comparator Thresholds

VBATTSNS Rising

VBATTSNS Falling

Hysteresis

9.2

9.1

9.75

9.50

250

10.3

9.9

BATTSNS Pin Current

VBATTSNS = 16V, RUN3 = 2V

VBATTSNS = 16V, RUN3 = 0V

±5

±50

µA

Note 1: Stresses beyond those listed under Absolute Maximum Ratings

may cause permanent damage to the device. Exposure to any Absolute

Maximum Rating condition for extended periods may affect device

reliability and lifetime.

Note 2: The LTC7811 is tested under pulsed load conditions such that

TJ ≈ TA. The LTC7811I is guaranteed over the –40°C to 125°C operating

junction temperature range, and the LTC7811J is guaranteed over the

–40°C to 150°C operating junction temperature range. High junction

temperatures degrade operating lifetimes; operating lifetime is derated

for junction temperatures greater than 125°C. Note that the maximum

ambient temperature consistent with these specifications is determined by

specific operating conditions in conjunction with board layout, the rated

package thermal impedance and other environmental factors. The junction

temperature (TJ, in °C) is calculated from the ambient temperature (TA, in

°C) and power dissipation (PD, in Watts) according to the formula: TJ = TA

+ (PD • θJA), where θJA (in °C/W) is the package thermal impedance.

Note 3: When SENSE1– ≥ 3.2V or EXTVCC ≥ 4.8V, VBIAS supply current is

transferred to these pins to reduce the total input supply quiescent current.

SENSE1– bias current is reflected to the buck channel 1 input supply (VIN1)

by the formula IVIN1 = ISENSE1– • VOUT1/(VIN1 • η), where η is the efficiency.

EXTVCC bias current is similarly reflected to a buck channel input supply

when biased by a buck channel output. To minimize input supply current,

select channel 1 to be the lowest output voltage greater than 3.2V and

connect EXTVCC to the lowest output voltage greater than 4.8V.

Note 4: The LTC7811 is tested in a feedback loop that servos VITH1,2,3 to

a specified voltage and measures the resultant VFB1,2,3. The specifications

at 0°C and 85°C are not tested in production and are assured by

design, characterization and correlation to production testing at other

temperatures (125°C for the LTC7811I, 150°C for the LTC7811J).

Note 5: Dynamic supply current is higher due to the gate charge being

delivered at the switching frequency. See Applications Information.

Note 6: Rise and fall times are measured using 10% and 90% levels. Delay

times are measured using 50% levels.

Note 7: The minimum on-time condition is specified for an inductor

peak-to-peak ripple current > 40% of IL(MAX) (See Minimum On-Time

Considerations in the Applications Information section).

Note 8: This IC includes overtemperature protection that is intended to

protect the device during momentary overload conditions. The maximum

rated junction temperature will be exceeded when this protection is active.

Continuous operation above the specified absolute maximum operating

junction temperature may impair device reliability or permanently damage

the device.

Note 9: Do not apply a voltage or current source to these pins. They must be

connected to capacitive loads only, otherwise permanent damage may occur.

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