LT3844EFE-PBF(RevB) Просмотр технического описания (PDF) - Linear Technology

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LT3844EFE-PBF
(Rev.:RevB)

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

Linear Technology 

LT3844

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

temperature range,

SENSE– = SENSE+ =

otherwise specifications are at TA

10V, SGND = PGND = SW = SYNC

=

=

25°C. VIN

0V, unless

= 20V, VCC

otherwise

= BOOST

noted.

=

BURST_EN

=

10V,

SHDN

=

2V,

RSET

=

49.9k,

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

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

Over Full Line and Load Range

VBURST_EN = 0V

VSHDN = 0V

Measured at VFB Pin

l

20

V

l

8

8.3

V

6.25

V

500

mV

l

1.7

2.1

mA

95

μA

20

μA

l –40

–120

mA

1.224

1.231

1.238

V

l 1.215

1.245

V

VFB Pin Input Current

SHDN Enable Threshold (Rising)

SHDN Threshold Hysteresis

VFB = 1.231V

25

nA

l 1.3

1.35

1.4

V

120

mV

Sense Pins Common Mode Range

Current Limit Sense Voltage

Input Current

(ISENSE+ + ISENSE–)

Operating Frequency

VSENSE+ – VSENSE–

VSENSE(CM) = 0V

VSENSE(CM) = 2V

VSENSE(CM) > 4V

l

0

36

V

l

90

100

115

mV

350

μA

–25

μA

–170

μA

290

300

310

kHz

l 270

330

kHz

Minimum Programmable Frequency

Maximum Programmable Frequency

l

l 500

100

kHz

kHz

External Sync Frequency Range

l 100

600

kHz

SYNC Input Resistance

40

kΩ

SYNC Voltage Threshold

l

1.4

2

V

Soft-Start Capacitor Control Current

2

μA

Error Amp Transconductance

l 270

340

410

μS

Error Amp DC Voltage Gain

62

dB

Error Amp Sink/Source Current

±30

μA

TG Drive On Voltage (Note 7)

TG Drive Off Voltage

TG Drive Rise/Fall Time

Minimum TG Off Time

CLOAD = 2200pF

CLOAD = 2200pF

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

l

9.8

V

0.1

V

40

ns

350

500

ns

Minimum TG On Time

l

250

350

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.

3844fb

3

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