71m6543h-igtr/f Maxim Integrated Products, Inc., 71m6543h-igtr/f Datasheet - Page 117

• Manufacturer Part Number: 71m6543h-igtr/f
• Description: Energy Meter Ic
• Manufacturer: Maxim Integrated Products, Inc.

5.3
High precision trim fuse values provided in the 71M6543H device cannot be directly accessed through the
I/O RAM space. These trim fuses reside in a special area termed the “Info Page”. The MPU gains access
to the Info Page by setting the INFO_PG (I/O RAM 0x270B[0]) control bit. Once the INFO_PG bit is set, Info
Page contents are accessible in program memory space based at the address specified by the contents
of CE_LCTN[5:0] (I/O RAM 0x2109[5:0]). CE_LCTN[5:0] specifies a base address at a 1KB address
boundary. Thus, the base address for the Info Page is at 1024*CE_LCTN[5:0]. Table 72 provides a list of
the available 71M6543H trim fuses and their corresponding offsets relative to the Info Page base
address. After reading the desired Info Page information, the MPU must reset the INFO_PG bit.
Offset
The code below provides an example for reading Info Page fuse trims. In this code example, the address,
"px" is a pointer to the MPU’s code space. In assembly language, the Info Page data objects, which are
read-only, must be accessed with the MOVC 8051 instruction.
In C, Info Page trim fuses must be fetched with a pointer of the correct width, depending whether an 8-bit
or a 16-bit data object is to be fetched. The case statements in the code example below perform casts to
obtain a pointer of the correct size for each object, as needed.
In assembly language, the MPU has to form 11-bit or 16-bit values from two separate 8-bit fetches,
depending on the object being fetched.
The byte values containing less than 8 valid bits are LSB justified. For example Info Page offset 0x90 is
an 8-bit object, whose three LSBs are bits [10:8] of the complete TEMP_85[10:0] 11-bit object. The Info
v1.0
0x90
0x91
0x92
0x93
0x94
Reading the Info Page (71M6543H only)
TRIMBGB[15:8]
LCDADJ12[7:0]
TEMP_85[10:8]
TRIMBGD[7:0]
TRIMBGB[7:0]
TEMP_85[7:0]
LCDADJ0[7:0]
TRIMBGB[15:0]
TEMP_85[10:0]
TRIMBGD[7:0]
Trim Fuse
(11-bits)
(16-bits)
(8-bits)
(8-bits)
(8-bits)
Name
© 2008–2011 Teridian Semiconductor Corporation
Object Size
Bit 7
8-bits
8-bits
8-bits
8-bits
8-bits
8-bits
8-bits
Figure 38. Trim Fuse Bit Mapping
Table 72. Info Page Trim Fuses
Bit 6
Address Offset
0x90
0x91
0x92
0x93
0x94
0x95
0x96
Bit 5
TRIMBGB[15:8]
TRIMBGB[7:0]
TRIMBGD[7:0]
TEMP_85[7:0]
Bit 4
TEMP_85[10:0] holds the
STEMP[10:0] reading at 85°C.
2’s complement format
TRIMBGB[15:0] holds the
deviation of VREF from its ideal
value (1.195V) at 85°C.
LSB = 0.1 mV
2’s complement format
TRIMBGD[7:0] holds the
deviation of VREF from its ideal
value (1.195V) at 22°C.
LSB = 0.1 mV
2’s complement format
LCDADJ12 = [VLCD-3.676v] at
22C when LCD_DAC=0C.
LSB=5mV. Two’s complement.
LCDADJ0 = [VLCD-2.65v] at
22C when LCD_DAC=0.
LSB=5mV. Two’s complement.
Bit 3 Bit 2 Bit 1 Bit 0
Comments
71M6543F/H Data Sheet
TEMP_85[10:8]
117