Pad                          Instance                    Clamp connections
							 DRN1   SRC1   DRN2  SRC2   B2B
----------------------------------------------------------------------------------------
sky130_ef_io__vddio_hvc_pad  \mgmt_vddio_hvclamp_pad[0]  vddio, vssio
sky130_ef_io__vddio_hvc_pad  \mgmt_vddio_hvclamp_pad[1]  vddio, vssio
sky130_ef_io__vssio_hvc_pad  \mgmt_vssio_hvclamp_pad[0]  vddio, vssio
sky130_ef_io__vssio_hvc_pad  \mgmt_vssio_hvclamp_pad[1]  vddio, vssio
-----------------------------------------------------------------------------------------
sky130_ef_io__vdda_hvc_pad    mgmt_vdda_hvclamp_pad      vdda,  vssa
sky130_ef_io__vssa_hvc_pad    mgmt_vssa_hvclamp_pad      vdda,  vssa
sky130_ef_io__vdda_hvc_pad    user1_vdda_hvclamp_pad     vdda1, vssa1
sky130_ef_io__vssa_hvc_pad   user1_vssa_hvclamp_pad      vdda1, vssa1
sky130_ef_io__vdda_hvc_pad   user2_vdda_hvclamp_pad      vdda2, vssa2
sky130_ef_io__vssa_hvc_pad   user2_vssa_hvclamp_pad      vdda2, vssa2
-----------------------------------------------------------------------------------------
sky130_ef_io__vccd_lvc_pad    mgmt_vccd_lvclamp_pad      vccd,  vssio, vccd,  vssd, vssa
sky130_ef_io__vssd_lvc_pad    mgmt_vssd_lvclmap_pad      vccd,  vssio, vccd,  vssd, vssa
-----------------------------------------------------------------------------------------
sky130_ef_io__vccd_lvc_pad   user1_vccd_lvclamp_pad      vccd1, vssd1, vccd1, vssd, vssio
sky130_ef_io__vssd_lvc_pad   user1_vssd_lvclmap_pad      vccd1, vssd1, vccd1, vssd, vssio
sky130_ef_io__vccd_lvc_pad   user2_vccd_lvclamp_pad      vccd2, vssd2, vccd2, vssd, vssio
sky130_ef_io__vssd_lvc_pad   user2_vssd_lvclmap_pad      vccd2, vssd2, vccd2, vssd, vssio
-----------------------------------------------------------------------------------------

Overlay types used:
1. hvc_pad:		vddio -> vssio
2. hvc_pad:		vdda  -> vssa
3. lvc_pad:		vccd  -> vssio,  vccd -> vssd    vssa
4. lvc_pad:		vccd  -> vssd, 	 vccd -> vssdG   vssio

NOTE:  Type (4) crosses domains, so that the local VCCD has a diode to the
local VSSD and also to the global VSSD.  BUT:  Although vccd goes all the way
around the chip in the form of vcchib, vssd does not, which makes the SRC2
connection effectively unreachable in this configuration, so better to just
change it to vssd1 and vssd2 for the respective domains.

New overlay types created:
1. sky130_ef_io__vddio_hvc_clamped_pad:	sky130_ef_io__vddio_hvc_pad + overlay (1)
2. sky130_ef_io__vssio_hvc_clamped_pad:	sky130_ef_io__vssio_hvc_pad + overlay (1)
3. sky130_ef_io__vdda_hvc_clamped_pad:	sky130_ef_io__vdda_hvc_pad  + overlay (2)
4. sky130_ef_io__vssa_hvc_clamped_pad:	sky130_ef_io__vssa_hvc_pad  + overlay (2)
5. sky130_ef_io__vccd_lvc_clamped_pad:	sky130_ef_io__vccd_lvc_pad  + overlay (3)
6. sky130_ef_io__vssd_lvc_clamped_pad:	sky130_ef_io__vssd_lvc_pad  + overlay (3)
7. sky130_ef_io__vccd_lvc_clamped2_pad:	sky130_ef_io__vccd_lvc_pad  + overlay (4)
8. sky130_ef_io__vssd_lvc_clamped2_pad:	sky130_ef_io__vssd_lvc_pad  + overlay (4)
9. sky130_ef_io__vccd_lvc_clamped3_pad:	sky130_ef_io__vccd_lvc_pad  + overlay (4)
10. sky130_ef_io__vssd_lvc_clamped3_pad: sky130_ef_io__vssd_lvc_pad + overlay (4)

NOTE:  The "clamped3" pads correspond to a change in the Caravel design for MPW-2,
in which the vccd/vssd domain has continuous supply rings around the chip
periphery.  The pad connection of these two pads does not connect to the padframe
power rings, but connects to a separate set of power rails in the chip core.