DS5003 Datasheet, PDF (23/24 Pages) Maxim Integrated Products – Secure Microprocessor Chip

Secure Microprocessor Chip
+5V
+3V
LITHIUM
+5V
13
54
V_CC
V_LI
V_CCO ¹²
10
R/W
DS5003 ^{CE1 74}
PORT 0
PORT 1
CE2 ²
BA14–BA0
PORT 2
PORT 3
14 _MSEL
BD7–BD0
GND ⁵²
28 _VCC
27
WE
20 _CS
32kB x 8 SRAM
OE ²²
A14–A0
D7–D0
14 _GND
28 _VCC
27 _WE
20
CS
32kB x 8 SRAM
22
OE
A14–A0
D7–D0
14
GND
Figure 14. Connection to 64kB x 8 SRAM
Power Management
The DS5003 monitors V_CC to provide power-fail reset,
early warning power-fail interrupt, and switchover to
lithium backup. It uses an internal bandgap reference
in determining the switch points. These are called
V_PFW, V_CCMIN, and V_LI, respectively. When V_CC drops
below V_PFW, the DS5003 performs an interrupt and
vectors to location 2Bh if the power-fail warning was
enabled. Full processor operation continues regard-
less. When power falls further to V_CCMIN, the DS5003
invokes a reset state. No further code execution is per-
formed unless power rises back above V_CCMIN. All
decoded chip enables and the R/W signal go to an
inactive (logic 1) state. V_CC is still the power source at
this time. When V_CC drops further to below V_LI, internal
circuitry switches to the lithium cell for power. The
majority of internal circuits are disabled and the remain-
ing nonvolatile states are retained. Any devices con-
nected to V_CCO are powered by the lithium cell at this
time. V_CCO is at the lithium battery voltage minus
approximately 0.45V (less a diode drop), depending on
the load. Low-power SRAMs should be used for this
reason. When using the DS5003, the user must select
the appropriate battery to match the SRAM data-reten-
tion current and the desired backup lifetime. Note that
the lithium cell is only loaded when V_CC < V_LI. The
Secure Microcontroller User’s Guide has more informa-
tion on this topic. The trip points V_CCMIN and V_PFW are
listed in the electrical specifications.
Package Information
(For the latest package outline information, go to
www.maxim-ic.com/DallasPackInfo.)
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
80 MQFP
—
56-G4005-001
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