ZHCSOS1 March 2022 TPS629210E
PRODUCTION DATA
- 1 特性
- 2 应用
- 3 说明
- 4 Revision History
- 5 Device Comparison Table
- 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 Mode Selection and Device Configuration (MODE/S-CONF Pin)
- 8.3.2 Adjustable VO Operation (External Voltage Divider)
- 8.3.3 Selectable VO Operation (VSET and Internal Voltage Divider)
- 8.3.4 Smart Enable with Precise Threshold
- 8.3.5 Power Good (PG)
- 8.3.6 Output Discharge Function
- 8.3.7 Undervoltage Lockout (UVLO)
- 8.3.8 Current Limit and Short Circuit Protection
- 8.3.9 Thermal Shutdown
- 8.4 Device Functional Modes
- 9 Application and Implementation
- 10Power Supply Recommendations
- 11Layout
- 12Device and Documentation Support
- 13Mechanical, Packaging, and Orderable Information
9.2.2.3.2 Inductor Selection
The TPS629210E is designed for a nominal 2.2-µH inductor. Larger values can be used to achieve a lower inductor current ripple but they can have a negative impact on efficiency and transient response. Smaller values than 2.2 µH cause larger inductor current ripple, which cause larger negative inductor currents in forced PWM mode and higher peak currents at full load. Therefore, they are not recommended at larger voltages across the inductor as it is the case for high input voltages and low output voltages. With low output current in forced PWM mode, this causes a larger negative inductor current peak that can exceed the negative current limit. At low or no output current and small inductor values, the output voltage can therefore not be regulated any more. More detailed information on further LC combinations can be found in the Optimizing the TPS62130/40/50/60 Output Filter Application Note.
The inductor selection is affected by several effects like the following:
- Inductor ripple current
- Output ripple voltage
- PWM-to-PFM transition point
- Efficiency
In addition, the inductor selected has to be rated for appropriate saturation current and DC resistance (DCR). Equation 14 calculates the maximum inductor current.
where:
- IL(max) is the maximum inductor current.
- ΔIL is the peak-to-peak inductor ripple current.
- L(min) is the minimum effective inductor value.
Calculating the maximum inductor current using the actual operating conditions gives the minimum saturation current of the inductor needed. It is recommended to add a margin of about 20%. A larger inductor value is also useful to get lower ripple current, but increases the transient response time and size as well. The following inductors have been used with the TPS629210E and are recommended for use:
| Type | Inductance [µH] | DCR [mΩ] | Current [A](1) | Dimensions [L×W×H] mm | Manufacturer |
|---|---|---|---|---|---|
| DFE201210U-1R5M(2) | 1.5 µH, ±20% | 115 | 2.5 | 2.0 × 1.2 × 1.0 | muRata |
| DFE252012PD-2R2M | 2.2 µH, ±20% | 84 | 2.8 | 2.5 × 2.0 × 1.2 | muRata |
| XGL3530-222ME | 2.2 μH, ±20% | 20 | 4.0 | 3.5 × 3.2 × 3 | Coilcraft |
| XGL4020-222ME | 2.2 µH, ±20% | 19.5 | 6.2 | 4 × 4 × 2.1 | Coilcraft |
| XGL3530-332ME | 3.3 μH, ±20% | 33 | 3.3 | 3.5 × 3.2 × 3 | Coilcraft |
| XGL4020-472ME | 4.7 µH, ±20% | 43 | 4.1 | 4 × 4 × 2.1 | Coilcraft |
The inductor value also determines the load current at which power save mode is entered:
