LTC7878

4

Rev. 0

For more information www.analog.com

ELECTRICAL CHARACTERISTICS The

l

denotes the specifications which apply over the specified operating

junction temperature range, otherwise specifications are at TA = 25°C. , VIN = 12V, RUN > 1.25V unless otherwise noted. (Note 2)

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 LTC7878 is tested under pulsed load conditions such that TJ

≈ TA. The LTC7878A is guaranteed to meet specifications from –40°C to

125°C junction temperature. 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 • JA), where θJA (in

°C/W) is the package thermal impedance.

Note 3: When VIN > EXTVCC and EXTVCC > 8V, VBIAS supply current is

transferred to EXTVCC pin to reduce the total input supply quiescent

current.

Note 4: The LTC7878 is tested in a feedback loop that servos VITH to

a specified voltage and measures the resultant VFB. The specifications

at –40°C and 125°C are not tested in production and are assured by

design, characterization and correlation to production testing at other

temperatures.

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

delivered at the switching frequency. See Applications Information section.

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.

Note 10: Guaranteed by design.

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

DRVCC and INTVCC Linear Regulators

VDRVCC

DRVCC Regulation Voltage

VIN = 12V, EXTVCC = 0V

VIN = 5V, EXTVCC = 12V

6.8

6.8

7

7

7.2

7.2

V

V

VDRVCC_LREG

DRVCC Voltage Load Regulation

IDRVCC = 0mA to 55mA, VIN = 12V

1

2

%

VINTVCC

INTVCC Regulation Voltage

4.8

5

5.2

V

Oscillator and Phase Locked Loop

IFREQ

FREQ Pin Output Current

9

10

11

µA

fSW(MIN)

Low Fixed Switching Frequency

VFREQ = 0V

50

kHz

fSW(MAX)

High Fixed Switching Frequency

VFREQ = 5V

800

kHz

fSW_SYNC

Synchronizable Frequency

SYNC = External Clock

100

600

kHz

VTH_SYNC

SYNC Pin Input Threshold

SYNC Pin Rising

1.2

2

V

SYNC Pin Falling

0.5

0.9

V

RSYNC

SYNC Pin Input Resistance to Ground

500

kΩ

Clock Output High Voltage

4.8

5

V

Clock Output Low Voltage

0

0.2

V

Power Good

VPGOOD

PGOOD Trip Level, VFB Respect to Set

Regulated Voltage

VFB Ramping Negative

–10

%

VFB Ramping Positive

10

%

RPGOOD

PGOOD Open Drain On-Resistance

55

Ω

IPGOOD

PGOOD Leakage Current

VPGOOD = 6V

±1

µA

Gate Drivers

RTG1, RTG2

Top Driver Pull-Up On-Resistance

BOOST – SW = 7V

3

Ω

Top Driver Pull-Down On-Resistance

BOOST – SW = 7V

1.5

Ω

RBG1, RBG2

Bottom Driver Pull-Up On-Resistance

DRVCC = 7V

3.5

Ω

Bottom Driver Pull-Down On-Resistance

DRVCC = 7V

3

Ω