LM3679 datasheet(4/24 Pages) TI

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LM3679

SNVS510A – SEPTEMBER 2007 – REVISED FEBRUARY 2008

www.ti.com

ELECTRICAL CHARACTERISTICS

(1) (2) (3)

Limits in standard typeface are for TJ = TA = 25°C. Limits in boldface type apply over the operating ambient temperature

range (

−30°C ≤ TA ≤ +85°C). Unless otherwise noted, specifications apply to the LM3679TL/UR with VIN = EN = 3.6V.

Symbol

Parameter

Condition

Min

Typ

Max

Units

VIN

Input Voltage

See(4)

2.5

5.5

VFB

Feedback Voltage

PWM mode

-2.5

+2.5

VREF

Internal Reference Voltage

0.5

ISHDN

Shutdown Supply Current

EN = 0V

0.01

µA

DC Bias Current into VIN

No load, device is not switching

µA

RDSON (P)

Pin-Pin Resistance for PFET

VIN= VGS= 3.6V, ISW= 100mA

350

450

Ω

RDSON (N)

Pin-Pin Resistance for NFET

VIN= VGS= 3.6V, ISW= -100mA

150

250

Ω

ILIM

Switch Peak Current Limit

Open Loop(5)

820

950

1075

VIH

Logic High Input

1.0

VIL

Logic Low Input

0.4

IEN

Enable (EN) Input Current

0.01

µA

FOSC

Internal Oscillator Frequency

PWM Mode

2.5

3.5

MHz

(1)

All voltages are with respect to the potential at the GND pin.

(2)

Min and Max limits are specified by design, test or statistical analysis. Typical numbers are not ensured, but do represent the most likely

norm.

(3)

The parameters in the electrical characteristic table are tested under open loop conditions at VIN= 3.6V unless otherwise specified. For

performance over the input voltage range and closed loop condition, refer to the datasheet curvescurves

(4)

Input voltage will depend on IOUT MAX value. IOUT MAX = 300mA -> VIN = 2.5 to 5.5V. IOUT MAX = 350mA - > VIN = 2.7V to 5.5V

(5)

Refer to datasheet curves for closed loop data and its variation with regards to supply voltage and temperature. Electrical Characteristic

table reflects open loop data (FB=0V and current drawn from SW pin ramped up until cycle by cycle current limit is activated). Closed

loop current limit is the peak inductor current measured in the application circuit by increasing output current until output voltage drops

by 10%.

DISSIPATION RATING TABLE

θJA

TA≤ 25°C

TA= 60°C

TA= 85°C

Power Rating

85°C/W (4-layer board)

1176 mW

765 mW

470 mW

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