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LTC1872

ABSOLUTE MAXIMUM RATINGS

(Note 1)

Input Supply Voltage (VIN).........................– 0.3V to 10V

SENSE –, NGATE Voltages ............ – 0.3V to (VIN + 0.3V)

VFB, ITH/RUN Voltages ..............................–0.3V to 2.4V

NGATE Peak Output Current (< 10

µs) ....................... 1A

Storage Ambient Temperature Range ... – 65

°C to 150°C

Operating Temperature Range (Note 2) .. – 40

°C to 85°C

Junction Temperature (Note 3) ............................. 150

°C

Lead Temperature (Soldering, 10 sec).................. 300

°C

PACKAGE/ORDER INFORMATION

TJMAX = 150°C, θJA = 230°C/ W

S6 PART MARKING

ORDER PART

NUMBER

LTC1872ES6

LTMK

Consult factory for parts specified with wider operating temperature ranges.

ELECTRICAL CHARACTERISTICS The q denotes specifications that apply over the full operating temperature

range, otherwise specifications are at TA = 25°C. VIN = 4.2V unless otherwise specified. (Note 2)

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Input DC Supply Current

Typicals at VIN = 4.2V (Note 4)

Normal Operation

2.4V

≤ VIN ≤ 9.8V

270

420

µA

Sleep Mode

2.4V

≤ VIN ≤ 9.8V

230

370

µA

Shutdown

2.4V

≤ VIN ≤ 9.8V, VITH/RUN = 0V

µA

UVLO

VIN < UVLO Threshold

µA

Undervoltage Lockout Threshold

VIN Falling

1.55

2.00

2.35

VIN Rising

1.85

2.10

2.40

Shutdown Threshold (at ITH/RUN)

0.15

0.35

0.55

Start-Up Current Source

VITH/RUN = 0V

0.25

0.5

0.85

µA

Regulated Feedback Voltage

°C to 70°C(Note 5)

0.780

0.800

0.820

–40

°C to 85°C(Note 5)

0.770

0.800

0.830

VFB Input Current

(Note 5)

Oscillator Frequency

VFB = 0.8V

500

550

650

kHz

Gate Drive Rise Time

CLOAD = 3000pF

Gate Drive Fall Time

CLOAD = 3000pF

Peak Current Sense Voltage

(Note 6)

114

120

ITH/RUN 1

GND 2

VFB 3

6 NGATE

5 VIN

4 SENSE–

TOP VIEW

S6 PACKAGE

6-LEAD PLASTIC SOT-23

Note 1: Absolute Maximum Ratings are those values beyond which the life

of a device may be impaired.

Note 2: The LTC1872E is guaranteed to meet performance specifications

from 0

°C to 70°C. Specifications over the –40°C to 85°C operating

temperature range are assured by design, characterization and correlation

with statistical process controls.

Note 3: TJ is calculated from the ambient temperature TA and power

dissipation PD according to the following formula:

TJ = TA + (PD • θJA°C/W)

Note 4: Dynamic supply current is higher due to the gate charge being

delivered at the switching frequency.

Note 5: The LTC1872 is tested in a feedback loop that servos VFB to the

output of the error amplifier.

Note 6: Guaranteed by design at duty cycle = 30%. Peak current sense

voltage is VREF/6.67 at duty cycle <40%, and decreases as duty cycle

increases due to slope compensation as shown in Figure 2.

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