低压差线性稳压器 (LDO)

[English]

简介

ESP32-P4 芯片内部集成了 4 路低压差线性稳压器 (LDO)，每路的电压都是可编程调节的。在硬件的参考设计中，我们通常会将其中一些的 LDO 输出作为内部 Flash 和 PSRAM 的电源，剩余的一些 LDO 可以用于给外部设备供电。

备注

使用前请阅读手册，确保你需要的电流不会超过芯片的规格。

功能概述

下文将分节介绍 LDO 驱动的功能：

LDO 通道申请

LDO 通道可以分为两种，一种是电压固定的，另一种是电压可调的。对于同一个输出通道，如果电压固定，那么可以允许有多个用户同时使用（软件允许一个变量拥有多个不可变引用）。如果电压可调，那么只能允许一个用户使用（软件上不允许一个变量有多个可变引用或者可变和不可变引用同时存在）。

LDO 通道在驱动软件中由 esp_ldo_channel_handle_t 句柄表示。申请 LDO 通道资源的函数是 esp_ldo_acquire_channel()。申请成功后，会返回一个 LDO 通道的句柄，这个句柄可以用于后续的电压调节操作。在申请通道的时候，我们需要通过 esp_ldo_channel_config_t 结构体来指定 LDO 通道的基本信息，包括通道 ID，期望的输出电压，以及电压是否可以动态调节。

由于允许多个用户同时使用固定电压的 LDO 通道，所以驱动内部会维持一个引用计数器。当最后一个用户释放 LDO 通道资源时，LDO 通道会被自动关闭。释放 LDO 通道资源的函数是 esp_ldo_release_channel()。另外还需要注意，申请和释放 LDO 通道在使用的时候需要成对出现。

LDO 通道电压调节

esp_ldo_channel_adjust_voltage() 函数用来在运行时调整 LDO 通道的输出电压。但是，这个函数只能用于可调节电压的 LDO 通道，否则会返回错误。

注意，由于硬件限制，LDO 通道电压的精度可能会 50~100mV 左右的偏差，请勿依赖于 LDO 通道的输出电压来进行精确的模拟量控制。

应用示例

API 参考

Header File

Functions

esp_err_t esp_ldo_acquire_channel(const esp_ldo_channel_config_t *config, esp_ldo_channel_handle_t *out_handle)

Acquire an LDO channel with the specified configuration.

备注

This function can't automatically search a LDO channel for you, you must specify a LDO channel ID manually, based on your schematic.

备注

The same channel can be acquired multiple times in different places of the application code, however, if the LDO channel is adjustable, you can't acquire it multiple times, in case user A changes the voltage and breaks the voltage setting of user B.

备注

You should release the channel by esp_ldo_release_channel when it's no longer needed.

参数

  • config -- [in] The configuration of the LDO channel

  • out_handle -- [out] The returned LDO channel handle

返回

  • ESP_OK: Acquire the LDO channel successfully

  • ESP_ERR_INVALID_ARG: Acquire the LDO channel failed due to invalid arguments

  • ESP_FAIL: Acquire the LDO channel failed due to other reasons

esp_err_t esp_ldo_release_channel(esp_ldo_channel_handle_t chan)

Release the LDO channel.

参数

chan -- [in] The LDO channel handle returned from esp_ldo_acquire_channel

返回

  • ESP_OK: Release the LDO channel successfully

  • ESP_ERR_INVALID_ARG: Release the LDO channel failed due to invalid arguments

  • ESP_ERR_INVALID_STATE: Release the LDO channel failed due to invalid state, e.g., the channel handle is double released

  • ESP_FAIL: Release the LDO channel failed due to other reasons

esp_err_t esp_ldo_channel_adjust_voltage(esp_ldo_channel_handle_t chan, int voltage_mv)

Adjust the voltage of the LDO channel.

参数

  • chan -- [in] The LDO channel handle returned from esp_ldo_acquire_channel

  • voltage_mv -- [in] The voltage value to be set to the LDO channel, in millivolts

返回

  • ESP_OK: Adjust the voltage of the LDO channel successfully

  • ESP_ERR_INVALID_ARG: Adjust the voltage of the LDO channel failed due to invalid arguments

  • ESP_ERR_NOT_SUPPORTED: Adjust the voltage of the LDO channel failed due to the channel is not adjustable

  • ESP_FAIL: Adjust the voltage of the LDO channel failed due to other reasons

esp_err_t esp_ldo_dump(FILE *stream)

Dump LDO channel status to the specified stream.

参数

stream -- [in] IO stream. Can be stdout, stderr, or a file/string stream.

返回

  • ESP_OK: Dump the LDO channel status successfully

  • ESP_FAIL: Dump the LDO channel status failed

Structures

struct esp_ldo_channel_config_t

LDO channel configurations.

Public Members

int chan_id

You must set the LDO channel ID according to the datasheet, e.g., set it to 1 for LDO_VO1

int voltage_mv

The voltage value to be set to the LDO channel

struct esp_ldo_channel_config_t::ldo_extra_flags flags

Flags for the LDO channel

struct ldo_extra_flags

Extra flags of a LDO channel.

Public Members

uint32_t adjustable

Whether the LDO channel is adjustable, and the voltage can be updated by esp_ldo_channel_adjust_voltage

uint32_t owned_by_hw

If the LDO channel is owned by hardware, then software configurations can be overridden by hardware (e.g. eFuse)

uint32_t bypass

Whether to bypass the regulator, i.e., the input voltage is sourced directly to the output

Type Definitions

typedef struct ldo_regulator_channel_t *esp_ldo_channel_handle_t

Type of LDO regulator channel handle.

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