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LTC7138

7138f

For more information www.linear.com/LTC7138

elecTrical characTerisTics The

denotes the specifications which apply over the specified operating

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

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Output Supply (VFB)

VFB(ADJ)

Feedback Comparator Threshold

(Adjustable Output)

VFB Rising, VPRG1 = VPRG2 = 0V

LTC7138E, LTC7138I

LTC7138H, LTC7138MP

0.792

0.788

0.800

0.808

0.812

VFBH

Feedback Comparator Hysteresis

(Adjustable Output)

VFB Falling, VPRG1 = VPRG2 = 0V

IFB

Feedback Pin Current

VFB = 1V, VPRG1 = VPRG2 = 0V

–10

VFB(FIXED)

Feedback Comparator Thresholds

(Fixed Output)

VFB Rising, VPRG1 = SS, VPRG2 = 0V

VFB Falling, VPRG1 = SS, VPRG2 = 0V

4.94

4.91

5.015

4.985

5.09

5.06

VFB Rising, VPRG1 = 0V, VPRG2 = SS

VFB Falling, VPRG1 = 0V, VPRG2 = SS

3.25

3.23

3.31

3.29

3.37

3.35

VFB Rising, VPRG1 = VPRG2 = SS

VFB Falling, VPRG1 = VPRG2 = SS

1.78

1.77

1.81

1.80

1.84

1.83

Operation

IPEAK

Peak Current Comparator Threshold

ISET Floating

100k Resistor from ISET to GND

ISET Shorted to GND

540

270

140

610

310

170

680

350

200

IVAL

Valley Current Comparator Threshold

Relative to IPEAK

ISET Floating

100k Resistor from ISET to GND

ISET Shorted to GND

RON

Power Switch On-Resistance

ISW = –100mA

1.8

ILSW

Switch Pin Leakage Current

VIN = 140V, SW = 0V

0.1

μA

ISS

Soft-Start Pin Pull-Up Current

VSS < 2.5V

μA

tINT(SS)

Internal Soft-Start Time

SS Pin Floating

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 LTC7138 is tested under pulsed load conditions such that

TJ ≈ TA. The LTC7138E is guaranteed to meet performance specifications

from 0°C to 85°C. Specifications over the –40°C to 125°C operating

junction temperature range are assured by design, characterization and

correlation with statistical process controls. The LTC7138I is guaranteed

over the –40°C to 125°C operating junction temperature range, the

LTC7138H is guaranteed over the –40°C to 150°C operating junction

temperature range and the LTC7138MP is tested and guaranteed over the

–55°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.

Note 3: 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 is 40°C/W for the MSOP package.

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.

Note 4: 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. The overtemperature protection level is not production tested.

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

delivered at the switching frequency. See Applications Information.

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