SNVSBU3 March   2021

PRODUCTION DATA

1. Features
2. Applications
3. Description
4. Revision History
5. Pin Configuration and Functions
6. Specifications
7. Detailed Description
1. 7.1 Overview
2. 7.2 Functional Block Diagram
3. 7.3 Feature Descriptions
1. 7.3.1  Step-Down DC/DC Converters
2. 7.3.2  Boost Converter
4. 7.3.4  Sync Clock Functionality
5. 7.3.5  Power-Up
6. 7.3.6  Buck and Boost Control
7. 7.3.7  Enable and Disable Sequences
8. 7.3.8  Window Watchdog
9. 7.3.9  Device Reset Scenarios
10. 7.3.10 Diagnostics and Protection Features
11. 7.3.11 OTP Error Correction
12. 7.3.12 Operation of GPO Signals
13. 7.3.13 Digital Signal Filtering
4. 7.4 Device Functional Modes
5. 7.5 Programming
1. 7.5.1 I2C-Compatible Interface
6. 7.6 Register Maps
1. 7.6.1 Register Descriptions
8. Application and Implementation
1. 8.1 Application Information
2. 8.2 Typical Application
1. 8.2.1 Design Requirements
2. 8.2.2 Detailed Design Procedure
1. 8.2.2.1 Application Components
3. 8.2.3 Current Limit vs Maximum Output Current
4. 8.2.4 Application Curves
9. Power Supply Recommendations
10. 10Layout
11. 11Device and Documentation Support
12. 12Mechanical, Packaging, and Orderable Information

• RHB|32
• RHB|32

### 8.2.3 Current Limit vs Maximum Output Current

The current limit must be set high enough to account for the inductor ripple current on top of the maximum output current for the buck converters and boost. The forward current limit for the buck converters is set by BUCK0_ILIM, BUCK1_ILIM and for boost it is set by BOOST_ILIM.

For the buck converter the inductor current ripple can be calculated using Equation 1 and Equation 2:

Equation 1.
Equation 2.

Example using Equation 1 and Equation 2:

 VIN(max) = 5.5 V VOUT = 1 V η = 0.75 fSW = 1.8 MHz L = 0.38 µH then D = 0.242 and ΔIL = 1.59 A

Peak current is half of the current ripple. If ILIM_FWD_SET_OTP is 3 A, the minimum forward current limit would be 2.85 A when taking the –5% tolerance into account. In this case the difference between set peak current and maximum load current = 0.795 A + 0.15 A = 0.945 A.

Figure 8-2 Current Limit vs Maximum Output Current