IMX51 View Datasheet(PDF) - Freescale Semiconductor

Part Name

Description

Manufacturer

IMX51

i.MX51 Applications Processors for Consumer and Industrial Products

Freescale Semiconductor 

Signal Name

PMIC_INT_REQ

POR_B

RESET_IN_B

RREFEXT

SGND, SVCC, and

SVDDGP

STR

TEST_MODE

VREF

VREFOUT

Features

Table 3. Special Signal Considerations (continued)

Remarks

When using the MC13892 power management IC, the PMIC_INT_REQ high-priority interrupt input

on i.MX51 should be either floated or tied to NVCC_SRTC_POW with a 4.7 kΩ to 68 kΩ resistor.

This avoids a continuous current drain on the real-time clock backup battery due to a 100 kΩ

on-chip pull-up resistor.

PMIC_INT_REQ is not used by the Freescale BSP (board support package) software. The BSP

requires that the general-purpose INT output from the MC13892 be connected to the i.MX51 GPIO

input GPIO1_8 configured to cause an interrupt that is not high-priority.

The original intent was for PMIC_INT_REQ to be connected to a circuit that detects when the

battery is almost depleted. In this case, the I/O must be configured as alternate mode 0 (ALT0 =

power fail).

This cold reset negative logic input resets all modules and logic in the IC.

Note: The POR_B input must be immediately asserted at power-up and remain asserted until

after the last power rail is at its working voltage.

This warm reset negative logic input resets all modules and logic except for the following:

• Test logic (JTAG, IOMUXC, DAP)

• SRTC

• Memory repair – Configuration of memory repair per fuse settings

• Cold reset logic of WDOG – Some WDOG logic is only reset by POR_B. See WDOG chapter

in i.MX51 Multimedia Applications Processor Reference Manual (MCIMX51RM) for details.

Determines the reference current for the USB PHY bandgap reference. An external 6.04 kΩ 1%

resistor to GND is required.

These sense lines provide the ability to sense actual on-chip voltage levels on their respective

supplies. SGND monitors differentials of the on-chip ground versus an external power source.

SVCC monitors on-chip VCC, and SVDDGP monitors VDDGP. Freescale recommends connection

of the SVCC and SVDDGP signals to the feedback inputs of switching power-supplies or to test

points.

This signal is reserved for Freescale manufacturing use. The user should float this signal.

TEST_MODE is for Freescale factory use only. This signal is internally connected to an on-chip

pull-down device. Users must either float this signal or tie it to GND.

When using VREF with DDR-2 I/O, the nominal 0.9 V reference voltage must be half of the

NVCC_EMI_DRAM supply. The user must tie VREF to a precision external resistor divider. Use a

1 kΩ 0.5% resistor to GND and a 1 kΩ 0.5% resistor to NVCC_EMI_DRAM. Shunt each resistor

with a closely-mounted 0.1 µF capacitor.

To reduce supply current, a pair of 1.5 kΩ 0.1% resistors can be used. Using resistors with

recommended tolerances ensures the ± 2% VREF tolerance (per the DDR-2 specification) is

maintained when four DDR-2 ICs plus the i.MX51 are drawing current on the resistor divider.

Note: When VREF is used with mDDR this signal must be tied to GND.

This signal determines the Triple Video DAC (TVDAC) reference voltage. The user must tie

VREFOUT to an external 1.05 kΩ 1% resistor to GND.

i.MX51 Applications Processors for Consumer and Industrial Products, Rev. 6

Freescale Semiconductor

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