1.2.6 Unused Pin Configurations

In cases where certain interfaces are not used, the associated pins need to be configured properly. For example, the pins of an unused crystal oscillator can be left floating (DNC) and must not be grounded. If a PLL is not used or bypassed, and only the divider circuitry is used, then the PLL’s pins can be powered without RC filter circuitry.

For SmartFusion2/IGLOO2 devices with multiple SerDes blocks, designers should tie off unused SerDes blocks, as shown in the following figure.

For banks configured as LPDDR or single-ended I/O (and MDDR or FDDR functionalities are not being used), VREFx can be left floating (DNC) even though the corresponding bank supply is still powered.

To allow a SmartFusion2/IGLOO2 device, to exit from reset, some of the bank supplies (VDDIx) must always be powered, even if associated bank I/Os are unused (as shown in Table 1-6 and Table 1-9).

For details on bank locations for all the devices, see DS0115: SmartFusion2 Pin Descriptions Datasheet or DS0124: IGLOO2 Pin Descriptions Datasheet .

Figure 1-3. Recommendations for Unused Pin Configurations1, 2
Important:
  1. For M2S090T(S), M2GL090T(S), M2S150T(S), and M2GL150T(S) devices, the VPP and VPPNVM must be connected to a 3.3V supply.
  2. SERDES_RXD pin connections are changed to VSS through a 10 kΩ resistor to reduce the latch-up risk. This change does not affect the old board design functionality.
  3. There are some exceptions. For recommendations on unused VDDI supplies, see the following tables. The SmartFusion2/IGLOO2 devices have multiple bank supplies. In cases where specific banks are not used, connect them as listed in the following tables. If there is no recommendation provided for a device-bank supply combination, it means that the bank is not pinned out.
Table 1-4. Recommendation for Unused Bank Supplies for FC1152, FG896, FG676, FCS536, and FCV484 Packages1
Bank Supply Names2 FC1152 FG896 FG676

FCS536 FCV484

M2S150T/

M2GL050T

M2S050T/

M2GL050T

M2S090T/

M2GL090T

M2S060T/

M2GL060T

M2S150T/

M2GL150T

M2S150T/

M2GL150

VDDI0

Connect to VSS through a 10 kΩ resistor

VDDI1

Connect to VSS through a 10 kΩ resistor

Must connect to VDDI1

Connect to VSS through a 10 kΩ resistor.

VDDI2

Connect to VSS through a 10 kΩ resistor

Must connect to VDDI2

Must connect to VDDI2

Must connect to VDDI2

Connect to VSS through a 10 kΩ resistor

VDDI3

Connect to VSS through a 10 kΩ resistor

Must connect to VDDI3

Must connect to VDDI3

Must connect to VDDI3

Connect to VSS through a 10 kΩ resistor

VDDI4

Connect to VSS through a 10 kΩ resistor

Must connect to VDDI4

Connect to VSS through a 10 kΩ resistor

VDDI5

Connect to VSS through a 10 kΩ resistor

VDDI6

Must connect to VDDI6

Connect to VSS through a 10 kΩ resistor

Must connect to VDDI6

Must connect to VDDI6

VDDI7

Must connect to VDDI7

Connect to VSS through a 10 kΩ resistor

Must connect to VDDI7

Must connect to VDDI7

VDDI8

Connect to VSS through a 10 kΩ resistor

VDDI9

Connect to VSS through a 10 kΩ resistor

Connect to VSS through a 10 kΩ resistor

VDDI10

Connect to VSS through a 10 kΩ resistor

Connect to VSS through a 10 kΩ resistor

VDDI11

Connect to VSS through a 10 kΩ resistor

Connect to VSS through a 10 kΩ resistor

VDDI12

Connect to VSS through a 10 kΩ resistor

Connect to VSS through a 10 kΩ resistor

VDDI13

Connect to VSS through a 10 kΩ resistor

Connect to VSS through a 10 kΩ resistor

VDDI14

Connect to VSS through a 10 kΩ resistor

Connect to VSS through a 10 kΩ resistor

VDDI15

Connect to VSS through a 10 kΩ resistor

Connect to VSS through a 10 kΩ resistor

VDDI16

Connect to VSS through a 10 kΩ resistor

Connect to VSS through a 10 kΩ resistor

VDDI17

Connect to VSS through a 10 kΩ resistor

Connect to VSS through a 10 kΩ resistor

VDDI18

Connect to VSS through a 10 kΩ resistor

Connect to VSS through a 10 kΩ resistor

Important:
  1. The unused VDDI# pins must be connected to VSS through a 10 kΩ resistor. The VDDI# pins can be grouped and connected to one 10 kΩ resistor or a 10 kΩ resistor can be used for each VDDI# bank, it completely depends on the board layout. In the earlier version of the document, the unused VDDI# pins were recommended to be configured as DNC, and this cannot create functionality issue. Microchip recommends connecting to Ground through a 10 kΩ resistor to improve the board reliability.
  2. These I/O bank supplies are mandatory power supplies and must be powered up, even if associated bank I/Os are in unused condition.
Table 1-5. Recommendation for Unused Bank Supplies for FG484 Package1

Bank Supply Names2

FG484

M2S090T/

M2GL090T

M2S060T/

M2GL060T

M2S050T/

M2GL050T

M2S025T/

M2GL025T

M2S010T/

M2GL010T

M2S005/

M2GL005

VDDI0

Connect to VSS through a 10 kΩ resistor

VDDI1

Connect to VSS through a 10 kΩ resistor

Must connect to VDDI1

Must connect to VDDI1

Must connect to VDDI1

Must connect to VDDI1

VDDI2

Must connect to VDDI2

Must connect to VDDI2

Must connect to VDDI2

Must connect to VDDI2

Must connect to VDDI2

VDDI3

Must connect to VDDI3

Must connect to VDDI3

Connect to VSS through a 10 kΩ resistor

Must connect to VDDI3

Connect to VSS through a 10 kΩ resistor

VDDI4

Connect to VSS through a 10 kΩ resistor

Must connect to VDDI4

Connect to VSS through a 10 kΩ resistor

Must connect to VDDI4

Connect to VSS through a 10 kΩ resistor

Must connect to VDDI4

VDDI5

Connect to VSS through a 10 kΩ resistor

VDDI6

Connect to VSS through a 10 kΩ resistor

VDDI7

Connect to VSS through a 10 kΩ resistor

VDDI8

Connect to VSS through a 10 kΩ resistor

VDDI9

Connect to VSS through a 10 kΩ resistor

Important:
  1. The unused VDDI# pins must be connected to VSS through a 10 kΩ resistor. The VDDI# pins can be grouped and connected to one 10 kΩ resistor or a 10 kΩ resistor can be used for each VDDI# bank, it completely depends on the board layout. In the earlier version of the document, the unused VDDI# pins were recommended to be configured as DNC, and this cannot create functionality issue. Microchip recommends connecting to Ground through a 10 kΩ resistor to improve the board reliability.
  2. These I/O bank supplies are mandatory power supplies and must be powered up, even if associated bank I/Os are in unused condition.
Table 1-6. Recommendation for Unused Bank Supplies for VF400 and FCS325 Packages1

Bank Supply Names 2

VF400

FCS325

M2S060T/

M2GL060T

M2S050T/

M2GL050T

M2S025T/

M2GL025T

M2S010T/

M2GL010T

M2S005/

M2GL005

M2S090T/

M2GL090T

M2S060T/

M2GL060T

M2S050T/

M2GL050T

M2S025T/

M2GL025T

VDDI0

Connect to VSS through a 10 kΩ resistor

Connect to VSS through a 10 kΩ resistor

VDDI1

Connect to VSS through a 10 kΩ resistor

Must connect to VDDI1

Must connect to VDDI1

Must connect to VDDI1

Must connect to VDDI1

Connect to VSS through a 10 kΩ resistor

Must connect to VDDI1

Must connect to VDDI1

VDDI2

Must connect to VDDI2

Must connect to VDDI2

Must connect to VDDI2

Must connect to VDDI2

Must connect to VDDI2

Must connect to VDDI2

Must connect to VDDI2

VDDI3

Must connect to VDDI3

Connect to VSS through a 10 kΩ resistor

Must connect to VDDI3

Must connect to VDDI3

Must connect to VDDI3

Connect to VSS through a 10 kΩ resistor

VDDI4

Must connect to VDDI4

Connect to VSS through a 10 kΩ resistor

Must connect to VDDI4

Connect to VSS through a 10 kΩ resistor

Must connect to VDDI4

Connect to VSS through a 10 kΩ resistor

Must connect to VDDI4

VDDI5

Connect to VSS through a 10 kΩ resistor

VDDI6

Connect to VSS through a 10 kΩ resistor

VDDI7

Connect to VSS through a 10 kΩ resistor

Connect to VSS through a 10 kΩ resistor

VDDI8

Connect to VSS through a 10 kΩ resistor

Connect to VSS through a 10 kΩ resistor

VDDI9

Connect to VSS through a 10 kΩ resistor

Connect to VSS through a 10 kΩ resistor

Important:
  1. The unused VDDI# pins must be connected to VSS through a 10 kΩ resistor. The VDDI# pins can be grouped and connected to one 10 kΩ resistor or a 10 kΩ resistor can be used for each VDDI# bank, it completely depends on the board layout. In the earlier version of the document, the unused VDDI# pins were recommended to be configured as DNC, and this cannot create functionality issue. Microchip recommends connecting to Ground through a 10 kΩ resistor to improve the board reliability.
  2. These I/O bank supplies are mandatory power supplies and must be powered up, even if associated bank I/Os are in unused condition.
Table 1-7. Recommendation for Unused Bank Supplies for VF256 and TQ144 Packages1

Bank Supply Names 2

VF256

TQ144

M2S025T/

M2GL025T

M2S010T/

M2GL010T

M2S005S/

M2GL005S

M2S010S/

M2GL010S

M2S005S/

M2GL005S

VDDI0

Connect to VSS through a 10 kΩ resistor

VDDI1

Must connect to VDDI1

Must connect to VDDI1

Must connect to VDDI1

VDDI2

Must connect to VDDI2

Must connect to VDDI2

Must connect to VDDI2

Must connect to VDDI2

Must connect to VDDI2

VDDI3

Connect to VSS through a 10 kΩ resistor

VDDI4

Must connect to VDDI4

Must connect to VDDI4

Must connect to VDDI4

Must connect to VDDI4

Must connect to VDDI4

VDDI5

Connect to VSS through a 10 kΩ resistor

Connect to VSS through a 10 kΩ resistor

VDDI6

Connect to VSS through a 10 kΩ resistor

VDDI7

Connect to VSS through a 10 kΩ resistor

Connect to VSS through a 10 kΩ resistor

Important:
  1. The unused VDDI# pins must be connected to VSS through a 10 kΩ resistor. The VDDI# pins can be grouped and connected to one 10 kΩ resistor or a 10 kΩ resistor can be used for each VDDI# bank, it completely depends on the board layout. In the earlier version of the document, the unused VDDI# pins were recommended to be configured as DNC, and this cannot create functionality issue. Microchip recommends connecting to Ground through a 10 kΩ resistor to improve the board reliability.
  2. These I/O bank supplies are mandatory power supplies and must be powered up, even if associated bank I/Os are in unused condition.