LTC1772HS6 データシートの表示（PDF） - Linear Technology

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LTC1772HS6

Constant Frequency Current Mode Step-Down DC/DC Controller in SOT-23

Linear Technology 

LTC1772

ELECTRICAL CHARACTERISTICS

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

of a device may be impaired.

Note 2: The LTC1772E is guaranteed to meet 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. The LTC1772I is guaranteed to meet specified

performance from –40°C to 85°C. The LTC1772H is guaranteed to meet

specified performance from –40°C to 140°C.

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)

Operation at high junction temperatures degrades operating lifetimes.

Operating lifetimes at junction temperatures greater than 125°C is derated

to 1000 hours.

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

delivered at the switching frequency.

Note 5: The LTC1772 is tested in a feedback loop that servos VFB to the

output of the error amplifier.

Note 6: Peak current sense voltage is reduced dependent on duty cycle to

a percentage of value as given in Figure 2.

TYPICAL PERFOR A CE CHARACTERISTICS

Reference Voltage

vs Temperature

825

VIN = 4.2V

820

815

810

805

800

795

790

785

780

775

–55 –35 –15 5 25 45 65 85 105 125 145

TEMPERATURE (°C)

1772 G01

Normalized Frequency

vs Temperature

10

VIN = 4.2V

8

6

4

2

0

–2

–4

–6

–8

–10

–55 –35 –15 5 25 45 65 85 105 125 145

TEMPERATURE (°C)

1772 G02

Undervoltage Lockout Trip

Voltage vs Temperature

2.14

VIN FALLING

2.10

2.06

2.02

1.98

1.94

1.90

1.86

1.82

1.78

1.74

–55 –35 –15 5 25 45 65 85 105 125 145

TEMPERATURE (°C)

1772 G03

Maximum (VIN – SENSE–) Voltage

vs Duty Cycle

130

VIN = 4.2V

120

TA = 25°C

110

100

90

80

70

60

50

20 30 40 50 60 70 80 90 100

DUTY CYCLE (%)

1772 G04

Shutdown Threshold

vs Temperature

550

VIN = 4.2V

510

470

430

390

350

310

270

230

190

150

–55 –35 –15 5 25 45 65 85 105 125 145

TEMPERATURE (°C)

1772 G05

1772fb

3

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