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LT3844EFE-PBF

High Voltage, Current Mode Switching Regulator Controller with Programmable Operating Frequency

Linear Technology 

LT3844

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

temperature range, otherwise specifications are at TA = 25°C. VIN = 20V, VCC = BOOST = BURST_EN = 10V, SHDN = 2V, RSET = 49.9kΩ,

SENSE– = SENSE+ = 10V, SGND = PGND = SW = SYNC = 0V, unless otherwise noted.

PARAMETER

VCC Operating Voltage Range (Note 5)

VCC Output Voltage

VCC UVLO Threshold (Rising)

VCC UVLO Threshold Hysteresis

VCC Supply Current (Note 6)

VCC Burst Mode Current

VCC Shutdown Current

VCC Current Limit

Error Amp Reference Voltage

VFB Pin Input Current

SHDN Enable Threshold (Rising)

SHDN Threshold Hysteresis

Sense Pins Common Mode Range

Current Limit Sense Voltage

Input Current

(ISENSE+ + ISENSE–)

Operating Frequency

Minimum Programmable Frequency

Maximum Programmable Frequency

External Sync Frequency Range

SYNC Input Resistance

SYNC Voltage Threshold

Soft-Start Capacitor Control Current

Error Amp Transconductance

Error Amp DC Voltage Gain

Error Amp Sink/Source Current

TG Drive On Voltage (Note 7)

TG Drive Off Voltage

TG Drive Rise/Fall Time

Minimum TG Off Time

Minimum TG On Time

CONDITIONS

Over Full Line and Load Range

VBURST_EN = 0V

VSHDN = 0V

Measured at VFB Pin

VFB = 1.231V

VSENSE+ – VSENSE–

VSENSE(CM) = 0V

VSENSE(CM) = 2V

VSENSE(CM) > 4V

MIN

●

●

●

● –40

1.224

● 1.215

● 1.3

●0

● 90

290

● 270

●

● 500

● 100

●

● 270

CLOAD = 2200pF

CLOAD = 2200pF

10% to 90% or 90% to 10%, CLOAD = 2200pF

●

●

TYP

8

6.25

500

1.7

95

20

– 120

1.231

25

1.35

120

100

350

–25

–170

300

40

1.4

2

340

62

±30

9.8

0.1

40

350

250

MAX

20

8.3

2.1

1.238

1.245

1.4

36

115

310

330

100

600

2

410

500

350

UNITS

V

V

V

mV

mA

μA

μA

mA

V

V

nA

V

mV

V

mV

μA

μA

μA

kHz

kHz

kHz

kHz

kHz

kΩ

V

μA

μS

dB

μA

V

V

ns

ns

ns

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 LT3844 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.

Note 3: The LT3844E is guaranteed to meet performance specifications from

0°C to 125°C junction temperature. Specifications over the –40°C to 125°C

operating junction temperature range are assured by design, characterization

and correlation with statistical process controls. The LT3844I is guaranteed

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

Note 4: VIN voltages below the start-up threshold (7.5V) are only

supported when the VCC is externally driven above 6.5V.

Note 5: Operating range is dictated by MOSFET absolute maximum VGS.

Note 6: Supply current specification does not include switch drive

currents. Actual supply currents will be higher.

Note 7: DC measurement of gate drive output “ON” voltage is typically

8.6V. Internal dynamic bootstrap operation yields typical gate “ON”

voltages of 9.8V during standard switching operation. Standard operation

gate “ON” voltage is not tested but guaranteed by design.

Note 8: The –1V absolute maximum on the SW pin is a transient

condition. It is guaranteed by design and not subject to test.

3844fa

3

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