ZHCSLI9A December 2021 – June 2022 TPS92623-Q1
PRODUCTION DATA
- 1 特性
- 2 應(yīng)用
- 3 說明
- 4 Revision History
- 5 Pin Configuration and Functions
- 6 Specifications
-
7 Detailed Description
- 7.1 Overview
- 7.2 Functional Block Diagram
- 7.3
Feature Description
- 7.3.1 Power Supply (SUPPLY)
- 7.3.2 Enable and Shutdown
- 7.3.3 Constant-Current Output and Setting (INx)
- 7.3.4 Thermal Sharing Resistor (OUTx and RESx)
- 7.3.5 PWM Control (PWMx)
- 7.3.6 Supply Control
- 7.3.7 Diagnostics
- 7.3.8 FAULT Bus Output with One-Fails-All-Fail
- 7.3.9 FAULT Table
- 7.3.10 LED Fault Summary
- 7.3.11 IO Pins Inner Connection
- 7.4 Device Functional Modes
- 8 Application and Implementation
- 9 Power Supply Recommendations
- 10Layout
- 11Device and Documentation Support
- 12Mechanical, Packaging, and Orderable Information
封裝選項(xiàng)
機(jī)械數(shù)據(jù) (封裝 | 引腳)
- PWP|16
散熱焊盤機(jī)械數(shù)據(jù) (封裝 | 引腳)
- PWP|16
訂購信息
8.2.2.2 Detailed Design Procedure
Step 1: Determine the current sensing resistor, R(SNSx) by using Equation 8.
where
- V(CS_REG) = 150 mV (typical)
- I(OUTx_Tot) = 130 mA
According to design requirements, output current for each channel is same so that the calculated R(SNS1) = R(SNS2) = R(SNS3)= 1.15 Ω.
Step 2: Design the current distribution between I(OUTx) and I(RESx), and calculate the current sharing resistor, R(RESx), by using Equation 9. The R(RESx) value actually decides the current distribution for I(OUTx) path and I(RESx) path, basic principle is to design the R(RESx) to consume appropriate 50% total power dissipation at typical supply operating voltage.
where
- V(SUPPLY) = 12 V (typical)
- I(OUTx_Tot) = 130 mA (maximum)
The calculated result for R(RESx) resistor value including R(RES1), R(RES2)and R(RES3) is 117 Ω when V(OUTx) is typical 2 × 2.2 V = 4.4 V.
Step 3: Design the threshold voltage of SUPPLY to enable the LED open-circuit, and calculate voltage divider resistor value for R1 and R2 on DIAGEN pin.
The maximum forward voltage of LED-string is 2 × 2.5 V = 5 V. To avoid the open-circuit fault reported in low-dropout operation conditions, additional headroom between SUPPLY and OUTx must be considered. TheTPS92623-Q1 device must disable open-circuit detection when the supply voltage is below LED-string maximum forward voltage plus V(OPEN_th_rising) and V(CS_REG). The voltage divider resistor, R1 and R2 value can be calculated by Equation 10.
where
- V(OPEN_th_rising) = 420 mV (maximum)
- V(CS_REG) = 156 mV (maximum)
- VIL(DIAGEN) = 1.045 V (minimum)
- R2 = 10 kΩ (recommended)
The calculated result for R1 is 43.4 kΩ when V(OUTx) maximum voltage is 5 V and V(CS_REG) is 156 mV.