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LTC1705

Dual 550kHz Synchronous Switching Regulator Controller with 5-Bit VID and 150mA LDO

Linear Technology 

LTC1705

ELECTRICAL CHARACTERISTICS

The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.

VCC = PVCC = BOOST = 5V, VINCLK = 3.3V unless otherwise specified. (Note 3)

SYMBOL PARAMETER

CONDITIONS

MIN TYP MAX UNITS

AFB

Feedback Amplifier DC Gain

GBW Feedback Amplifier Gain Bandwidth Product f = 100kHz (Note 7)

q 74

85

dB

20

MHz

ICOMP

VPGOOD

Feedback Amplifier Output Sink/Source Current

Negative Power Good Threshold

Positive Power Good Threshold

Relative to Nominal Output Voltage

q ±3

±10

mA

q –15 –10

–6

%

q6

10

15

%

AILIM Current Limit Amplifier DC Gain

IIMAX IMAX Source Current

Core, I/O Supply Switching Characteristics

VIMAXC = VIMAXIO = 0V

q 40

60

dB

q –12 –10

–8

µA

fOSC

Oscillator Frequency

ΦOSC Core and I/O Oscillator Phase Difference

DCMAX Maximum Duty Cycle

tNOV

Driver Nonoverlap

tr, tf

Driver Rise/Fall Time

Clock Supply Output

Test Circuit 1

(Note 7)

Test Circuit 1, 50% to 50%

Test Circuit 1, 10% to 90%

q 460

550

650

kHz

180

DEG

q 87

90

93

%

q 10

25

120

ns

q

15

100

ns

VOUTCLK CLK Output Voltage

IVOUTCLK = 0mA

q 2.45 2.50 2.55

V

dVOUTCLK Output Voltage Line Regulation

VINCLK = 3.0V to 5.5V

q

±0.02 ±0.1

%/V

Output Voltage Load Regulation

IVOUTCLK = 0mA to 150mA

q – 0.1 – 0.05

%

ILMCLK CLK Output Short-Circuit Current

IVOUTCLK = 0V

q

– 240 –150

mA

VDROPOUT CLK Output Dropout Voltage

IVOUTCLK = 150mA, dVOUTCLK = –1% (Note 8)

q

0.3

0.5

V

VPGOOD Negative VOUTCLK Power Good Threshold

Positive VOUTCLK Power Good Threshold

Relative to VOUTCLK

Relative to VOUTCLK

q –15 –10

–6

%

q6

10

15

%

VID Inputs

R1

Resistance Across SENSEC and FBC

10

kΩ

RVID

VVID

PGOOD

VID Input Pull-Up Resistance

VID Input Threshold

(Note 9)

30

kΩ

q 0.4

1.6

V

IPGOOD VPGOOD Sink Current

Power Good

Power Bad

q

q 10

10

µA

mA

VOLPG

TPGOOD

PGOOD Output Low Voltage

VPGOOD Falling Edge Delay

VPGOOD Rising Edge Delay

VPBAD Pulse

IPGOOD = 1mA

VID Code Change

q

0.03

0.1

V

q2

4

8

µs

q 10

20

40

µs

q 10

20

40

µs

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

of a device may be impaired.

Note 2: The LTC1705 is guaranteed to meet performance 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.

Note 3: All currents into device pins are positive; all currents out of device

pins are negative. All voltages are referenced to ground unless otherwise

specified.

Note 4: PVCC and BVCC (VBOOST – VSW) must be greater than VGS(ON) of

the external MOSFETs to ensure proper operation.

Note 5: Supply current in normal operation is dominated by the current

needed to charge and discharge the capacitance of the external MOSFET

gates. This current varies with supply voltage and the choice of external

MOSFETs.

Note 6: Supply current in shutdown is dominated by external MOSFET

leakage and may be significantly higher than the quiescent current drawn

by the LTC1705, especially at elevated temperature.

Note 7: Guaranteed by design, not subject to test.

Note 8: Dropout voltage is the minimum input-to-output voltage

differential required to maintain regulation at the specified output current.

In dropout, the output voltage will be equal to VINCLK – VDROPOUT.

Note 9: Each internal pull-up resistor attached to the VID inputs has a

series diode connected to VCC to allow input voltages higher than the VCC

supply without damage or clamping. (See Block Diagram.)

Note 10: The core feedback voltage accuracy is guaranteed by the VSENSE

output voltage accuracy test.

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