JAJSKO7D October   2020  – March 2022

PRODUCTION DATA

1. 特長
2. アプリケーション
3. 概要
4. Revision History
5. Device Comparison Table
6. Pin Configuration and Functions
7. Specifications
8. Detailed Description
1. 8.1 Overview
2. 8.2 Functional Block Diagram
3. 8.3 Feature Description
4. 8.4 Device Functional Modes
1. 8.4.1 Shutdown Mode
2. 8.4.2 Standby Mode
3. 8.4.3 Active Mode
9. Application and Implementation
1. 9.1 Application Information
2. 9.2 Typical Application
1. 9.2.1 Design Requirements
2. 9.2.2 Detailed Design Procedure
3. 9.2.3 Application Curves
3. 9.3 What to Do and What Not to Do
10. 10Power Supply Recommendations
11. 11Layout
1. 11.1 Layout Guidelines
2. 11.2 Layout Example
12. 12Device and Documentation Support
13. 13Mechanical, Packaging, and Orderable Information

• RPE|9
• RPE|9

### 8.3.12 Input Supply Current

The LMR436x0-Q1 is designed to have very low input supply current when regulating light loads. This is achieved by powering much of the internal circuitry from the output. The VOUT/FB pin in the fixed-output voltage variants is the input to the LDO that powers the majority of the control circuits. By connecting the VOUT/FB input pin to the output node of the regulator, a small amount of current is drawn from the output. This current is reduced at the input by the ratio of VOUT / VIN as described in Equation 2.

Equation 2. ${I}_{QVIN}={I}_{Q}+{I}_{EN}+{I}_{BIAS}*\frac{{V}_{OUT}}{{\eta }_{eff}*{V}_{IN}}$

where

• IQVIN is the total standby (switching) current consumed by the operating (switching) buck converter when unloaded.
• IQ is the current drawn from the VIN terminal.
• IEN is current drawn by the EN terminal. Include this current if EN is connected to VIN. Check ILKG-EN in Section 7.5 for IEN.
• IBIAS is bias current drawn by the BIAS LDO.
• ηeff is the light-load efficiency of the buck converter with IQVIN removed from the input current of the buck converter. ηeff = 0.8 is a conservative value that can be used under normal operating conditions.