LTC1844 datasheet(4/12 Pages) LINER

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LTC1844 Series

1844fa

ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C. VIN = VOUT + 0.5V, unless otherwise noted. (Note 2)

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

LTC1844-1.5

IOUT = 50mA

●

115

160

IOUT = 150mA

●

350

450

LTC1844-BYP

IOUT = 50mA

●

IOUT = 150mA

●

135

200

LTC1844-SD

IOUT = 50mA

●

IOUT = 150mA

●

135

200

ILIM

Output Current Limit

●

160

350

Output Voltage Noise

f = 10Hz to 100kHz, CBP = 0.1µF, COUT = 10µF, IL = 150mA

µVRMS

f = 10Hz to 100kHz, CBP = 0.1µF, COUT = 1µF, IL = 150mA

µVRMS

VSHDN

SHDN Input Threshold

●

0.35

0.65

0.9

tDELAY

Shutdown Exit Delay

CBP = 0.01µF, COUT = 1µF, No load

100

µs

CBP = 0.01µF, COUT = 1µF, No load

●

200

µs

TSHDN

Thermal Shutdown Limit

155

°C

∆TSHDN

Thermal Shutdown Hysteresis

°C

IADJ

ADJ Pin Bias Current

(Notes 3, 8)

●

100

IIRL

Input Reverse Leakage Current

LTC1844-3.3, LTC1844-2.8, LTC1844-2.5, LTC1844-1.8,

●

200

500

µA

LTC1844-1.5, VIN = –5V, VOUT = 0V

LTC1844-BYP, LTC1844-SD, VIN = –5V, VOUT = 0V

●

1000

1500

µA

IORL

Output Reverse Leakage Current

VIN = 0V, VOUT = VOUT(NOMINAL)

0.01

0.1

µA

(Note 9)

VIN = 0V, VOUT = VOUT(NOMINAL)

●

1.2

µA

VOSH

Start-Up Overshoot

RL = 1k, SHDN Rise Time ≤ 1µs2

%VOUT

VRP

Output Ripple Rejection

(VIN – VOUT) = 1V (Avg), VRIPPLE = 0.5VP-P,50

fRIPPLE = 120Hz, ILOAD = 100mA

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

of a device may be impaired.

Note 2: The LTC1844 is tested and specified under pulse load conditions

such that TJ ≈ TA. The LTC1844E is guaranteed to meet performance

specifications from 0

°C to 70°C. Specifications over the –40°C to 125°C

operating junction temperature range are assured by design,

characterization and correlation with statistical process controls.

Note 3: The LTC1844 adjustable versions are tested and specified for

these conditions with the ADJ pin connected to the OUT pin for a

VOUT(NOMINAL) of 1.25V.

Note 4: Operating conditions are limited by maximum junction

temperature. The regulated output voltage specification will not apply for

all possible combinations of input voltage and output current. When

operating at maximum input voltage, the output current range must be

limited. When operating at maximum output current, the input voltage

range must be limited.

Note 5: The LTC1844’s high precision degrades slightly at high

temperatures (TJ > 70°C) with input voltages below 2.2V. The lower output

voltage versions have been split into higher and lower accuracy input

voltage ranges to reflect this.

Note 6: To ensure adequate input supply voltage, the LTC1844 adjustable

versions are tested and specified for these conditions with an external

resistor divider (two 100k resistors) for an output voltage of 2.50V. The

external resistor divider will add a 5

µA load on the output.

Note 7: Dropout voltage is (VIN – VOUT) when VOUT falls to 100mV below

its nominal value measured at VIN = VOUT + 0.5V. For example, the

LTC1844-3.3 is tested by measuring the VOUT at VIN = 3.8V, then VIN is

lowered until VOUT falls 100mV below the measured value. The difference

(VIN – VOUT) is then measured and defined as ∆VDO.

Note 8: ADJ pin bias current flows into the ADJ pin.

Note 9: Output reverse leakage current is tested with the IN pin grounded

and the OUT pin forced to the rated output voltage.

Note 10: This IC includes overtemperature protection that is intended to

protect the device during momentary overload conditions. Junction

temperature will exceed 125

°C when overtemperature protection is active.

Continuous operation above the specified maximum operating junction

temperature may impair device reliability.

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