SNVS797B March   2012  – October 2015 LM3492HC , LM3492HC-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Switching Frequency
      2. 8.3.2  LDO Regulator
      3. 8.3.3  Enable and Disable
      4. 8.3.4  Current Limit
      5. 8.3.5  Thermal Protection
      6. 8.3.6  Dynamic Headroom Control, Over-Ride, and Soft-Start
      7. 8.3.7  Current Regulator
      8. 8.3.8  Output Voltage Feedback
      9. 8.3.9  Overvoltage Protection
      10. 8.3.10 Bidirectional Communication Pin
        1. 8.3.10.1 Power-Good Indication
        2. 8.3.10.2 Overtemperature Indication
        3. 8.3.10.3 Output Current Undervoltage Indication
        4. 8.3.10.4 Switching Frequency Tuning
    4. 8.4 Device Functional Modes
    5. 8.5 Programming
      1. 8.5.1 Output Current Overvoltage Indication
      2. 8.5.2 COMM Pin Bit Pattern
      3. 8.5.3 Channel 1 Disable
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
        1. 9.2.1.1 RFB1, RFB2, and CFB
        2. 9.2.1.2 L1
        3. 9.2.1.3 D1
        4. 9.2.1.4 CIN and COUT
        5. 9.2.1.5 CVCC
        6. 9.2.1.6 CCDHC
        7. 9.2.1.7 RRT and RIREF
        8. 9.2.1.8 RCOMM
      2. 9.2.2 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Related Links
    2. 12.2 Community Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

6 Pin Configuration and Functions

PWP Package
20 Pin HTSSOP
Top View
LM3492HC-Q1 LM3492HC pwp20_pinout_lusc65.gif

Pin Functions

PIN TYPE(1) DESCRIPTION
NAME NO.
CDHC 11 I Dynamic headroom control. An external capacitor connected to this pin sets the DHC sensitivity. At start-up, a 12- µA internal current source charges an external capacitor to provide a soft-start function.
COMM 13 I/O Bidirectional logic communication. This pin is open drain for various indications (power-good, overtemperature, IOUT overvoltage and undervoltage) and command sending (switching frequency tuning and channel 1 disabling).
DIM1/CLK 15 I/O Dimming control of channel 1. Control the on and off of the current regulator of channel 1. This pin is internally pulled low by a 5-µA current. This pin also serves as a clock signal for latching input and output data of the COMM pin.
DIM2 16 I Dimming control of channel 2. Control the on and off of the current regulator of channel 2. This pin is internally pulled low by a 5-µA current.
EN 1 I Enable input. Contains an internal pullup. Connect to a voltage higher than 1.63 V to provide precision enable for the device.
FB 7 I Output voltage feedback. The output voltage is connected to this pin through a feedback resistor divider for output voltage regulation. The voltage of this pin is from 1.05 V to 2.5 V.
GND 8 G Analog signal ground. Connect to the exposed pad directly beneath the device.
ILIM 20 I Peak current limit adjust. Connecting an external resistor from the ILIM pin to the VCC pin reduces peak current limit. Connect the ILIM pin to ground to obtain the maximum current limit.
IOUT1 10 I Current regulator input for channel 1. Input of the current regulator of channel 1. The regulated current is programmable (see the IREF pin).
IOUT2 9 I Current regulator input for channel 2. Input of the current regulator of channel 2. The regulated current is programmable (see the IREF pin).
IREF 12 I Current setting pin for the current regulators. An external resistor connected from this pin to ground programs the regulated current of the current regulator of channels 1 and 2.
LGND 14 G Current regulator ground. Must be connected to the GND pin and exposed pad for normal operation. The LGND and GND pins are not internally connected.
PGND 17 G Integrated MOSFET ground. Must be connected to the GND pin and exposed pad for normal operation. The PGND and GND pins are not internally connected.
18
RT 6 I Frequency control pin. An external resistor from the VOUT pin to this pin sets the switching frequency.
SW 3 I Switch node. Internally connected to the drain of the integrated MOSFET.
4
VCC 19 O Internal LED regulator output. Nominally regulated to 5.5 V. Connect a capacitor of 0.47-μF or larger between the VCC and GND pins.
VIN 2 I Input supply voltage pin. Input voltage range is from 4.5 V to 65 V.
VOUT 5 I Output voltage sense pin. Senses the output voltage for nearly constant switching frequency control.
Exposed Pad G Thermal connection pad. Connect to a ground plane.
(1) I = Input, O = Output, G = Ground