Datasheet

LM3478
LM3478-Q1
SNVS085V –JULY 2000–REVISED FEBRUARY 2013 www.ti.com
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
I
SEN
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.
V
IN
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 -0.4V < V
FB
< 7V
FA/SD Pin Voltage -0.4V < V
FA/SD
< 7V
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
Human Body Model
(2)
2kV
Lead Temperature Vapor Phase (60 sec.) 215°C
Infrared (15 sec.) 260°C
DR Pin Voltage −0.4V ≤ VDR ≤ 8V
I
SEN
Pin Voltage 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 1.5kΩ resistor into each pin.
Operating Ratings
(1)
Supply Voltage 2.97V ≤ V
IN
≤ 40V
Junction Temperature Range −40°C ≤ T
J
≤ +125°C
Switching Frequency 100kHz ≤ F
SW
≤ 1MHz
(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 Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated
Product Folder Links: LM3478 LM3478-Q1