SLVA371A Datasheet, PDF (3/10 Pages) Texas Instruments – Powering Freon with TPS65070

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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 = 100kΩ 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
RTC_CVDD
1.2 V
External LDO
USB0_VDDA33,
USB1_VDDA33
3.3 V
DCDC1
DVDD3318_A,
DVDD3318_B,
DVDD3318_C
3.3 V / 1.8 V
DCDC2
CVDD
1.2 V
DCDC3
VDDARNWA. VDDARNW1,
PLL0_VDDA, PLL1_VDDA,
SATA_VDD, USB_CVDD,
USB0_VDDA12
1.2 V
LDO2
USB0_VDDA18,
USB1_VDDA18,
DDR_DVDD18,
SATA_VDDR, DVDD18
1.8 V
LDO1
(1) _{If VDVV3318 is configured for 3.3 V, LDO1 and LDO2 can ramp up together.}
Sequencing Order
1
5
4 / 5 (part of automatic sequence)
2 (part of automatic sequence)
3 (part of automatic sequence)
4 ⁽¹⁾
SLVA371A – February 2010 – Revised April 2010
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Powering Freon with TPS65070
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