The R5F1008D pairs the intermediate 48 KB code flash with the 3 by 3 mm
25-ball wafer-level package, giving Renesas a part for dense consumer boards
that need a mid-sized program store and no footprint at all. It carries the 3
KB RAM that distinguishes the 48 KB members, the 4 KB data flash of the
small-memory row, six converter channels and twenty-one I/O, and it keeps the
entire RL78/G13 protection architecture inside a package where the only
external surface is the ball array.

Forty-eight blocks under the balls

The array divides into forty-eight one-kilobyte blocks, the first four forming
the boot cluster and the second four forming the swap target at 02000H when
the feature is enabled. Both clusters duplicate the option bytes at 010C0H and
the identifiers at 010C4H, and the boot flag in block 0 decides which set is
live. On consumer boards built around this part the swap feature is common
because the products get firmware updates in the field, which means a
recovered dump has to capture both clusters and the flag state, or half the
history of the board is missing.

Three KB of RAM, one specific window

The 48 KB members map their 3 KB of volatile memory to FF300H through FFEFFH,
and the flash library’s self-RAM window on these parts starts at FF300H. That
single address tells two stories at once. It shows that the image was built
for self-programming, because the reservation only appears when the library
is linked in. And it fixes where a readout loader can live: the region below
FF300H is small but sufficient for a streaming routine, while the window
itself stays untouched so that a repair which ends in rewriting a block can
use the same layout the original authors did.

Four-byte words and interrupted writes

Programming happens in four-byte words with per-block erase and verify. An
interrupted update leaves the classic signature: a word holding a mixture of
old and new bits, surrounded by intact content, at the boundary the updater
had reached. On a part in this package the signature is often the only clue
that the unit died during a field update rather than from hardware failure,
and distinguishing the two is the first fork in any recovery job on this
member.

Getting to the balls

Twenty-five balls at 0.5 mm pitch under a 3 by 3 mm body leave no room for
blind probing. The practical routes are the board’s own test features, a
lift-and-reball onto an adapter, or a fixture that contacts the footprint
directly with sprung pins. Which route applies depends on whether the board
routes the single-wire TOOL0 pad anywhere reachable; many do, because the
factory needs it once. When none of the electrical routes exist, the work
moves to the package level, which is the domain of the IC decapsulation service service and
the chip reverse engineering service examination flow.

The protection posture as shipped

Nothing in the small package changes the shipped state: block protection
enabled, the debug gate controlled by 000C3H with its erase-on-failure bit,
two ten-byte identifiers in block 0, and the serial path through TOOL0 on P40
gated by its own identifier. The half-configured boards, where one identifier
is set and the other is not, are as common here as on the leaded members, and
finding which of the two states a given board is in is usually the first
fifteen minutes of the job.

Row context

The 16 and 64 KB members of the 25-pin package are in R5F1008A program memory and
R5F1008E memory dump, the leaded 24-pin equivalents are under R5F1007A memory readout and
R5F1007D locked flash, and the 48 KB die in a leaded 30-pin package is catalogued as
R5F100AD code flash extraction. For the same intermediate memory class in a package with real
leads and more converter channels, the 40-pin 48 KB member is described under
R5F100ED memory dump. General service handling for the whole family is on the
MCU crack service page.

Reading the ordering code

The part number itself answers three questions before the package is ever
lifted. The fixed prefix identifies the RL78/G13 group, the numeral that
follows selects the 25-ball wafer-level package, and the final letter gives
the program store, with D standing for the 48 KB class and its 3 KB of
volatile memory. Because the capacity also fixes the data-flash size at
4 KB and the converter at six inputs, the code is effectively a complete
data sheet entry compressed into eight characters, which is why recovering
a legible marking, even a partial one, is worth an hour of work before any
electrical route is attempted.