From Texas Instruments Embedded Processors Wiki

Contents 1 Introduction 1.1 Features 1.2 Block Diagram 1.3 Signal Description 1.4 Configuration and Operation 1.4.1 Power on sequencing 1.5 Schematic and Layout 1.6 Board/Schematic Modifications 1.7 More Information

Introduction

The TPS65023 Power Module is a plug-in board for the OMAP3EVM. It demonstrates a discrete power solution for OMAP3 and can be used to power the entire OMAP3EVM. It provides an alternate power solution for customers needing a more focused solution for their OMAP3 based design.

Note: This wiki describes rev E2 boards.

Features

Here is a summary of the features which are supported with the TPS65023 Power Module:

• satisfies power up sequencing for OMAP35x
• provides power for all voltage rails of OMAP35x
• 32KHz oscillator
• global reset control
• provides power for MMC1 (1.8V or 3.0V)
• provides power for VDAC
• enable/disable control for VDAC voltage
• enables voltage scaling via I2C connection to DCDC converters
• can control one DCDC converter with either I2C1 or I2C4
• enables class-2 Smart Reflex for VDD_MPU_IVA
• OMAP3 GPIOs can control:

DVI_NDIS (DVI enable/disable on OMAP3EVM)

LCD_ENBKL (enable/disable LCD backlight on OMAP3EVM)

MMC1_CD input (MMC1 card detect input from OMAP3EVM)

Although the TPS65023 Power Module provides most of the power requirements for OMAP3, it does not provide many of the features that are available with the OMAP3EVM default power module which contains the TPS65950. Here is a table of the differences:

Feature	TPS65950 Power Module	TPS65023 Power Module	Comments
Power Supplies
Input Voltage Range	2.1V – 4.5V	1.5V – 6.5V
VDD1	1.1A DCDC	1500mA DCDC1	Power for ARM and DSP Processors
VDD2	600mA	1200mA DCDC2	Power for OMAP3 core
VIO	600mA	1000mA DCDC3	1.8V I/O power
VPLL1	40mA	200mA LDO	1.8V power for PLLs
VPLL2	60mA	Yes	Can optionally connect to VPLL1 if needed. Powers OMAP3 VDD_SDI and VDDS_DSI (both not used by EVM)
VAUX1	200mA	No	Only used for EVM expansion connector
VAUX2	100mA	No	Only used for EVM expansion connector
VAUX3	200mA	No	Used for battery on EVM
VAUX4	100mA	Yes (connected to VIO)
VDDS_MMC1	220mA	200mA	1.8V or 3.0V is supported. No enable/disable control. This voltage is always enabled.
VDDS_MMC2	100mA	No	Only used for EVM expansion connector
VDAC	65mA	150mA (Enable/Disable controlled using OMAP3 GPIO)	Power for Video DAC.
VRSIM	60mA	No	Not used on EVM
VBUS	Yes	No	Power for USB
Keypad	Yes	No
Audio Codec	Yes	No
Interrupts	Yes	Yes	Interrupt output of TPS65023 is connected to OMAP3
USB PHY	Yes	No
ADC	Yes	No
Battery Charger	Yes	No
GPIOs
OSK_EN	Yes	No	This is enabled by default on the OMAP3EVM main board.
MMC1_CD	Yes	Yes, using OMAP3 GPIO140
DVI_nDISABLE	Yes	Yes, using OMAP3 GPIO142
DRM_MSECURE	Yes	No
LCD_ENBKL	Yes	Yes, using OMAP3 GPIO141
LED Driver	Yes	No
32KHz clock	Oscillator inside TPS65950	Onboard external Oscillator
High Frequency clock	Onboard external Oscillator	Onboard external Oscillator
Reset	POR and Warm Reset	POR
RTC	Yes	No
I2C control of voltage	HS I2C	FS I2C	I2C voltage control only on DCDC1
Sleep modes	Yes	No

Block Diagram

The above diagram shows the block diagram of the TPS65023 power module, along with a block diagram of a subset of the main board and how the power module connects to OMAP3. The following are the major components used on the power module:

Part Number	Description	Function
TPS65023	PMIC, 3 DCDC converters, 2 LDOs, I2C controllable	Powers most voltage rails of OMAP3, plus provides reset and sequencing.
TPS72118	Single output LDO	Used to power VDAC on OMAP3
SG-3030LC	32KHz clock oscillator	Used for OMAP3 low frequency functions. The clock is gated and buffered before it goes back to the OMAP3EVM main board using an AND gate.

Signal Description

The following is a description of the signals on the TPS65023 Power Module

Signal	Description
VAUX4_OUT	This can be optionally connected to 1.8V via R26. Used on expansion connector of OMAP3EVM
VDDS_MMC1	Voltage for MMC1. POR value is 3.3V but can be adjusted to 1.8V or 3.0V. This voltage is always on.
1.8V_VDDA_DAC	Voltage for VDAC
1.8V	1.8V I/O voltage for OMAP3 and OMAP3EVM
DVI_NDIS	DVI enable. Connected to GPIO_142 on OMAP3, and enables/disables the DVI transmitter on the OMAP3EVM main board. 0 = disabled 1 = enabled This signal is 1 after power on reset
MMC1_CD	MMC1 card detect. Connected to GPIO_9 on OMAP3. This signal should be setup as an input into OMAP3 to determine level of MMC1 card detect signal.
LCD_ENBKL	LCD Backlight enable. Connected to GPIO_141 on OMAP3, and enables/disables the backlight on the LCD screen on the OMAP3EVM main board. 0 = disabled 1 = enabled This signal is 1 after power on reset
VDAC_EN	Enable for VDAC voltage. Connected to GPIO_143 on OMAP3, and enables/disables the 1.8V for Video DAC. 0 = disabled 1 = enabled This signal is 1 after power on reset
I2C2_SCL, I2C2_SDA	I2C1 signals. These signals are labeled on the TPS65023 and EVM main board schematic as I2C2. They get swapped in hardware to I2C1 on the processor card. So these are actually connected to the I2C1 port of OMAP3 and can be used to control the TPS65023 DCDC1 converter
I2C4_SCL, I2C4_SDA	I2C4 signals. These are connected to the I2C4 port of OMAP3 and can be used to control the TPS65023 DCDC1 converter It is recommended that these not be used to control TPS65023. I2C1 provides more flexibility and read/write capabilities
I2C_SDA, I2C_SCL	I2C signals to control the DCDC1 converter. These can be connected to I2C1 on OMAP3 (using R19 and R21) or I2C4 on OMAP3 (using R20 and R22)
NRESPWRON	Power on Reset to OMAP3. The RESPWRON signal from TPS65023 control this signal. The TRESPWRON input of the TPS65023 control the timing of this signal. See the TPS65023 datasheet for more information.
SYS_NIRQ	Interrupt output of TPS65023. Connected to interrupt input of OMAP3 SYS_nIRQ.
VDD_MPU_IVA	Voltage for VDD_MPU_IVA rail of OMAP3
VBAT	Main 4.2V coming from OMAP3EVM
VDD_CORE	Voltage for VDD_CORE rail of OMAP3
1.8V_VDDS_DPLL	Voltage for OMAP3 PLL rail
DCDC1_EN	Enable signal for DCDC1 converter. Used for power sequencing.
VRTC	RTC voltage. Only used for power sequencing. Not used for any RTC function.
1.8VPG	1.8V Power Good. This is sourced from the 1.8V LDO and is used for proper power sequencing of the other voltage rails

Configuration and Operation

There are a few configuration options available on the TPS65023 power module

Source for I2C signals: You can choose to control DCDC1 converter on the power module with either I2C1 or I2C4 of OMAP3.
Note: The schematics for TPS65023 and EVM main board are mislabeled with respect to I2C1 and I2C2. On the TPS65023, signals labeled I2C2 actually connect to I2C1 on OMAP3.

To use I2C1, populate R19 and R21 with 0ohm resistors, and depopulate R20 and R22

Although there are provisions to be able to connect I2C4, this is not recommended. These connections are only used for test purposes.

Do not populate all four R19, R20, R21, R22 with 0ohm resistors at the same time. I2C communication will not work.

I2C1 can be used to read/write registers in the TPS65023 on the power module. It can be used to support Class 2 Smart Reflex on OMAP3. This is the recommended configuration.

I2C4 can only be used to write registers in the TPS65023 on the power module. The TPS65023 can only support Class 2 Smart Reflex. It is recommended that you use I2C1 for I2C communication because of its read/write capabilities.

For more information on Smart Reflex, please refer to the OMAP3 documentation.

VAUX4 power: You can connect/disconnect VAUX4 (if needed on the EVM main board) to 1.8V

To connect VAUX4 to 1.8V, populate R26 with 0ohm resistor.

To disconnect VAUX4, depopulate R26.

VPLL2 power: You can connect/disconnect VPLL2 (if needed on the EVM main board) to VPLL1 if needed.

To connect VPLL2 to VPLL1 (1.8V), populate R25 with 0ohm resistor.

To disconnect VPLL2, depopulate R25.

Reset timing: You can adjust the reset active time at power up by changing capacitor C7, which is connected to TRESPWRON signals of TPS65023. Refer to the TPS65023 datasheet for more information.

MMC1 voltage: On power up, MMC1 voltage (VDDS_MMC1) is 3.3V (this is the default value and cannot be changed). You can adjust this down to either 1.8V or 3.0V using I2C commands to the TPS65023 (see TPS65023 datasheet for more details). This allows for MMC booting from 3.3V MMC/SD cards.

VDAC voltage: Video DAC voltage (1.8V_VDDA_DAC) is supplied by the power module through a discrete LDO. The LDO has a fixed output of 1.8V, and can be enabled/disabled using OMAP3 GPIO_143:

GPIO_143 = 0 = disabled

GPIO_143 = 1 = enabled

Interrupts: Interrupts are available on the TPS65023 for power good monitoring of each DCDC and LDO. This interrupt output is connected directly to OMAP3 SYS_nIRQ0 and can be used to detect power faults on the TPS65023.

Power on sequencing

The diagram below shows the required power up sequencing as specified in the OMAP3 data manual.

The TPS65023 power module performs the following sequence on power up

1. When VBAT is applied, it enables DCDC3 on the TPS65023 via DCDC3_EN. This ramps 1.8V (connected to VDDS_WKUP_BG, VDDS_MEM, VDDS, and VDDS_SRAM on OMAP3)

2. The TPS65023 asserts RESPWRON

3. When 1.8V is ramped, 1.8VPG (1.8V Power Good) is active, and 32KHz oscillator is activated and begins to stabilize.

4. Also, when 1.8V is ramped, 1.8VPG enables DCDC2, which supplies VDD_CORE. This ramps to 1.15V when enabled.

5. 1.8VPG enables the high frequency clock coming from the EVM main board.

6. VDD_CORE is the sense input for the LOWBAT_SNS signal. When this reaches the appropriate threshold, this asserts LOWBAT, which is the DCDC1 enable signal. This starts the ramp of VDD_MPU_IVA.

7. DCDC1_EN also enables the ramp of LDO1 and LDO2. LDO1 supplies VDDS_DPLL_DLL and VDDS_DPLL_PER on OMAP3. LDO2 supples VDDS_MMC1 on OMAP3. There are no separate enable signals for LDO1 and LDO2 on TPS65023, so we leave VDD_MMC1 always on.

8. All of the above occurs within the TRESPWRON time period, after which the TPS65023 releases SYS_NRESPWRON, which allows OMAP3 to start running code.

9. Optionally, VDDA_DAC can be enabled when needed using OMAP3 GPIO connected to the TPS72118.

Schematic and Layout

Schematic (pdf)

Layout (pdf)

Board/Schematic Modifications

• None

More Information

Please refer to the TPS65023 Design In Guide wiki for more information on design considerations between the TPS65023 and OMAP35x.

• None

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