LM3478

LM3478-Q1

SNVS085V – JULY 2000 – REVISED FEBRUARY 2013

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Connection Diagram

Figure 2. 8-Lead VSSOP-8 Package

Figure 3. 8-Lead SOIC-8 Package

Table 1. Pin Descriptions

Pin Name

Pin No.

Description

1

Current sense input pin. Voltage generated across an external sense resistor is fed into this pin.

COMP

2

Compensation pin. A resistor, capacitor combination connected to this pin provides compensation for the

control loop.

FB

3

Feedback pin. The output voltage should be adjusted using a resistor divider to provide 1.26V at this pin.

AGND

4

Analog ground pin.

PGND

5

Power ground pin.

DR

6

Drive pin. The gate of the external MOSFET should be connected to this pin.

FA/SD

7

Frequency adjust and Shutdown pin. A resistor connected to this pin sets the oscillator frequency. A high level

on this pin for longer than 30 µs will turn the device off. The device will then draw less than 10µA from the

supply.

8

Power Supply Input pin.

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam

during storage or handling to prevent electrostatic damage to the MOS gates.

Absolute Maximum Ratings

(1)

Input Voltage

45V

FB Pin Voltage

FA/SD Pin Voltage

Peak Driver Output Current (<10µs)

1.0A

Power Dissipation

Internally Limited

Storage Temperature Range

−65°C to +150°C

Junction Temperature

+150°C

ESD Susceptibility

2kV

Lead Temperature

Vapor Phase (60 sec.)

215°C

Infrared (15 sec.)

260°C

DR Pin Voltage

−0.4V ≤ VDR ≤ 8V

500mV

(1)

Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which

operation of the device is intended to be functional. For guaranteed specifications and test conditions, see the Electrical Characteristics.

(2)

The human body model is a 100 pF capacitor discharged through a 1.5k

Ω resistor into each pin.

Operating Ratings

(1)

Supply Voltage

2.97V

Junction Temperature Range

Switching Frequency

100kHz

(1)

Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which

operation of the device is intended to be functional. For guaranteed specifications and test conditions, see the Electrical Characteristics.

2

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