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Sequencing with TPS65070

1.3

Power-Down Sequence

The power supplies can be powered off in any order as long as LVCMOS supplies operated at 3.3 V

(DVDD3318_A, DVDD3318_B, or DVDD3318_C) never exceed static 1.8-V supplies by more than 2 V.

There is no specific required voltage ramp-down rate for any of the supplies (except as required to meet

the stated voltage condition). The power-down sequence of the TPS65070 is the reversed power-up

sequence.

To meet the power-down requirements described here, an additional resistor divider R1 and R2 is

required to disable DCDC1 fast enough to ensure that the voltage difference between DCDC2 and

DCDC1 does not exceed 2.0 V. The TPS3805 does have a threshold voltage of 1.226 V at the SENSE

input. Using an external resistor divider, with R1 = 100k

Ω and R2 = 390kΩ, sets the trip voltage when

DCDC1 is disabled to 1.55 V. This configuration should ensure the difference between DCDC1 and

DCDC2 never exceeds 2.0 V.

2

Sequencing with TPS65070

The TPS65070 power management unit supports the power requirements of the OMAP-L138; the single

highly-integrated Power Management device provides the voltage settings and sequencing for the

OMAP-L138. Table 3 lists the output rail configuration for the TPS65070.

Table 3. TPS65070 Output Rail Configuration

Rail

Voltage

Converter

Sequencing Order

RTC_CVDD

1.2 V

External LDO

1

USB0_VDDA33,

3.3 V

DCDC1

5

USB1_VDDA33

DVDD3318_A,

DVDD3318_B,

3.3 V / 1.8 V

DCDC2

4 / 5 (part of automatic sequence)

DVDD3318_C

CVDD

1.2 V

DCDC3

2 (part of automatic sequence)

VDDARNWA. VDDARNW1,

PLL0_VDDA, PLL1_VDDA,

1.2 V

LDO2

3 (part of automatic sequence)

SATA_VDD, USB_CVDD,

USB0_VDDA12

USB0_VDDA18,

USB1_VDDA18,

1.8 V

LDO1

4

(1)

DDR_DVDD18,

SATA_VDDR, DVDD18

(1)

If VDVV3318 is configured for 3.3 V, LDO1 and LDO2 can ramp up together.

3

SLVA371A – February 2010 – Revised April 2010

Powering Freon with TPS65070

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