ZHCSFO3D November 2016 – August 2021 LM5170-Q1
PRODUCTION DATA
- 1 特性
- 2 應用
- 3 說明
- 4 Revision History
- 5 說明（續）
- 6 Pin Configuration and Functions
- 7 Specifications
-
8 Detailed Description
- 8.1 Overview
- 8.2 Functional Block Diagram
- 8.3
Feature Description
- 8.3.1 Bias Supply (VCC, VCCA)
- 8.3.2 Undervoltage Lockout (UVLO) and Master Enable or Disable
- 8.3.3 High Voltage Input (VIN, VINX)
- 8.3.4 Current Sense Amplifier
- 8.3.5 Control Commands
- 8.3.6 Channel Current Monitor (IOUT1, IOUT2)
- 8.3.7 Cycle-by-Cycle Peak Current Limit (IPK)
- 8.3.8 Error Amplifier
- 8.3.9 Ramp Generator
- 8.3.10 Soft Start
- 8.3.11 Gate Drive Outputs, Dead Time Programming and Adaptive Dead Time (HO1, HO2, LO1, LO2, DT)
- 8.3.12 PWM Comparator
- 8.3.13 Oscillator (OSC)
- 8.3.14 Synchronization to an External Clock (SYNCIN, SYNCOUT)
- 8.3.15 Diode Emulation
- 8.3.16 Power MOSFET Failure Detection and Failure Protection (nFAULT, BRKG, BRKS)
- 8.3.17 Overvoltage Protection (OVPA, OVPB)
- 8.4 Device Functional Modes
- 8.5 Programming
-
9 Application and Implementation
- 9.1 Application Information
- 9.2
Typical Application
- 9.2.1
60-A, Dual-Phase, 48-V to 12-V Bidirectional Converter
- 9.2.1.1 Design Requirements
- 9.2.1.2
Detailed Design Procedure
- 9.2.1.2.1 Determining the Duty Cycle
- 9.2.1.2.2 Oscillator Programming
- 9.2.1.2.3 Power Inductor, RMS and Peak Currents
- 9.2.1.2.4 Current Sense (RCS)
- 9.2.1.2.5 Current Setting Limits (ISETA or ISETD)
- 9.2.1.2.6 Peak Current Limit
- 9.2.1.2.7 Power MOSFETS
- 9.2.1.2.8 Bias Supply
- 9.2.1.2.9 Boot Strap
- 9.2.1.2.10 RAMP Generators
- 9.2.1.2.11 OVP
- 9.2.1.2.12 Dead Time
- 9.2.1.2.13 IOUT Monitors
- 9.2.1.2.14 UVLO Pin Usage
- 9.2.1.2.15 VIN Pin Configuration
- 9.2.1.2.16 Loop Compensation
- 9.2.1.2.17 Soft Start
- 9.2.1.2.18 ISET Pins
- 9.2.1.3 Application Curves
- 9.2.1
60-A, Dual-Phase, 48-V to 12-V Bidirectional Converter
- 10Power Supply Recommendations
- 11Layout
- 12Device and Documentation Support
- 13Mechanical, Packaging, and Orderable Information
9.2.1.2.18 ISET Pins
To control the current setting by an analog voltage, ground the ISETD pin. To control the current setting by a PWM signal, there are two options to choose.
The first option is to use the built-in ISETD-to-ISETA decoder as shown in Figure 8-4. The PWM duty cycle to ISETA voltage conversion ratio satisfies Equation 8. The selection of CISETA and FISETD should be constrained by Equation 1 and Equation 4. The advantages of this option include convenience and current control accuracy. The drawback is the delay it may cause.
Another option is to use an external two-stage RC filter to convert the PWM ISETD signal to a DC voltage feeding the ISETA pin as shown in Figure 9-13. To achieve the same ISETA ripple voltage, this option only requires CISETA =1.5 nF, and the delay time of this two-stage filter is only 10% of the built-in decoder, or 15 μs versus the built-in decoder’s 150 μs. The drawback of this option is the conversion errors if the PWM signal voltage levels are not well regulated. This option is more suitable for operation under a closed digital outer voltage loop because the ISETD to ISETA conversion error can be readily compensated by the closed outer voltage loop.
Figure 9-13 Two-Stage RC Filter to Convert the PWM into an Analog Voltage at the ISETA Pin