SLVSC42A August   2013  – April 2015 TPS22967

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Typical Application Schematic
  5. 5 Revision History
  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: VBIAS = 5 V
    6. 7.6 Electrical Characteristics: VBIAS = 2.5 V
    7. 7.7 Switching Characteristics
    8. 7.8 Typical Characteristics
      1. 7.8.1 Typical AC Scope Captures at TA = 25ºC, CT = 1 nF
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 ON/OFF Control
      2. 8.3.2 Adjustable Rise Time
      3. 8.3.3 Quick Output Discharge
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Input Capacitor (Optional)
      2. 9.1.2 Output Capacitor (Optional)
      3. 9.1.3 VIN and VBIAS Voltage Range
      4. 9.1.4 Safe Operating Area (SOA)
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Inrush Current
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Trademarks
    2. 12.2 Electrostatic Discharge Caution
    3. 12.3 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

封装选项

机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)
订购信息

8 Detailed Description

8.1 Overview

The TPS22967 device is a single-channel, 4-A load switch in an 8-pin WSON package. To reduce the voltage drop in high current rails, the device implements an ultra-low resistance N-channel MOSFET. The device has a programmable slew rate for applications that require specific rise time.

The device has very low leakage current during off state. This prevents downstream circuits from pulling high standby current from the supply. Integrated control logic, driver, power supply, and output discharge FET eliminates the need for any external components, which reduces solution size and bill of materials (BOM) count.

8.2 Functional Block Diagram

TPS22967 fbd_SLVSC42.gif

8.3 Feature Description

This section describes the integrated features for the TPS22967.

8.3.1 ON/OFF Control

The ON pin controls the state of the switch. Asserting ON high enables the switch. ON is active high and has a low threshold, making it capable of interfacing with low-voltage signals. The ON pin is compatible with standard GPIO logic thresholds. It can be used with any microcontroller with 1.2 V or higher GPIO voltage. This pin cannot be left floating and must be driven either high or low for proper functionality.

8.3.2 Adjustable Rise Time

A capacitor to GND on the CT pin sets the VOUT slew rate. The voltage on the CT pin can be as high as 12 V. Therefore, the minimum voltage rating for the CT capacitor must be 25 V for optimal performance. An approximate formula for the relationship between CT and slew rate is (Equation 1 accounts for 10% to 90% measurement on VOUT and does NOT apply for CT = 0 pF. Use Table 1 to determine rise times for when CT = 0 pF):

Equation 1. TPS22967 eq1_lvsbj0.gif

where

  • SR = slew rate (in µs/V).
  • CT = the capacitance value on the CT pin (in pF).
  • The units for the constant 13.4 is in µs/V. The units for the constant 0.39 are in µs/(V × pF).

Rise time can be calculated by multiplying the input voltage by the slew rate. Table 1 contains rise time values measured on a typical device. Rise times shown below are only valid for the power-up sequence where VIN and VBIAS are already in steady state condition, and the ON pin is asserted high.

Table 1. Rise Times On a Typical Device

CTx (pF) RISE TIME (µs) 10% - 90%, CL = 0.1 µF, CIN = 1 µF, RL = 10 Ω
TYPICAL VALUES at 25°C, 25 V X7R 10% CERAMIC CAPACITOR
5 V 3.3 V 1.8 V 1.5 V 1.2 V 1.05 V 0.8 V
0 127 93 62 55 51 46 42
220 475 314 188 162 141 125 103
470 939 637 359 304 255 218 188
1000 1869 1229 684 567 476 414 344
2200 4020 2614 1469 1211 1024 876 681
4700 8690 5746 3167 2703 2139 1877 1568
10000 18360 12550 6849 5836 4782 4089 3449

8.3.3 Quick Output Discharge

The TPS22967 includes a Quick Output Discharge (QOD) feature. When the switch is disabled, a discharge resistor is connected between VOUT and GND. This resistor has a typical value of 225 Ω and prevents the output from floating while the switch is disabled.

8.4 Device Functional Modes

Table 2 describes the functional state of the load switch as determined by the ON pin.

Table 2. Functional Table

ON VIN to VOUT VOUT to GND
L Off On
H On Off