LT1507 Просмотр технического описания (PDF) - Linear Technology

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LT1507

500kHz Monolithic Buck Mode Switching Regulator

Linear Technology 

LT1507

ELECTRICAL CHARACTERISTICS

TJ = 25°C, VIN = 5V, VC = 1.5V, boost open, switch open unless otherwise specified.

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Switch Frequency

Switch Frequency Line Regulation

Frequency Shifting Threshold on FB Pin

Minimum Input Voltage (Note 2)

VC Set to Give 50% Duty Cycle

– 25°C ≤ TJ ≤ 125°C

TJ ≤ –25°C

4.3V ≤ VIN ≤ 15V

∆f = 10kHz

460

500

540

kHz

440

560

kHz

440

570

kHz

q

0.05

0.15

%/ V

q 0.8

1.0

1.3

V

q

4

4.3

V

Minimum Boost Voltage (Note 3)

Boost Current (Note 4)

Input Supply Current (Note 5)

ISW ≤ 1.5A

VBOOST = VIN + 5V

q

ISW = 500mA, –25°C ≤ TJ ≤ 125°C

TJ ≤ –25°C

ISW = 1.5A, –25°C ≤ TJ ≤ 125°C

TJ ≤ –25°C

q

3

3.5

V

12

22

mA

25

mA

25

35

mA

40

mA

3.8

5.4

mA

Shutdown Supply Current

Lockout Threshold

Shutdown Threshold

VSHDN = 0V, VIN ≤ 12V

VSW = 0V, VC Open

VC Open

VC Open

Device Shutting Down

Device Starting Up

15

50

µA

q

75

µA

q 2.3

2.38

2.46

V

q 0.15

0.37

0.70

V

q 0.25

0.45

0.70

V

Minimum Synchronizing Amplitude

q

1.5

2.2

V

Synchronizing Frequency Range (Note 7)

580

1000

kHz

The q denotes specifications which apply over the operating temperature

range.

Note 1: Gain is measured with a VC swing equal to 200mV above the low

clamp level to 200mV below the upper clamp level.

Note 2: Minimum input voltage is not measured directly, but is guaranteed

by other tests. It is defined as the voltage where internal bias lines are still

regulated, so that the reference voltage and oscillator frequency remain

constant. Actual minimum input voltage to maintain a regulated output will

depend on output voltage and load current. See Applications Information.

Note 3: This is the minimum voltage across the boost capacitor needed to

guarantee full saturation of the internal power switch.

Note 4: Boost current is the current flowing into the BOOST pin with the

pin held 5V above input voltage. It flows only during switch ON time.

Note 5: Input supply current is the bias current drawn by the VIN pin when

the SHDN pin is held at 1V (switching disabled).

Note 6: Switch ON resistance is calculated by dividing VIN to VSW voltage

by the forced current (1.5A). See Typical Performance Characteristics for

the graph of switch voltage at other currents.

Note 7: For synchronizing frequency above 700kHz, with duty cycles

above 50%, external slope compensation may be needed. See Applications

Information.

Note 8: Transconductance and voltage gain refer to the internal amplifier

exclusive of the voltage divider. To calculate gain and transconductance

refer to SENSE pin on fixed voltage parts. Divide values shown by the ratio

VOUT/ 2.42.

TYPICAL PERFORMANCE CHARACTERISTICS

VC Pin Shutdown Threshold

1.4

1.2

Switch Peak Current Limit

100

VIN = 5V

VOUT = 3.3V

90

1.0

80

0.8

70

0.6

60

Feedback Pin Voltage and Current

2.44

2.0

2.43

1.5

VOLTAGE

2.42

1.0

CURRENT

2.41

0.5

0.4

–50 –25 0 25 50 75 100 125

JUNCTION TEMPERATURE (°C)

LT1507 • TPC01

50

0

0.25 0.50 0.75 1.00 1.25

LOAD CURRENT (A)

LT1507 • TA02

2.40

0

–50 –25 0 25 50 75 100 125

JUNCTION TEMPERATURE (°C)

LT1507 • TPC03

3

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