© 2016 Integrated Device Technology, Inc.
Step 1: Assigning Unique Identification
Assigning a unique identification number is as simple as using the commands Program T
SETL
, Program Tcg, and
Program Tco. These three 8-bit registers will allow for 16M unique devices. In addition, Gain_B must be
programmed to 800
H
(unity), and Gain_T must be programmed to 80
H
(unity).
Step 2: Data Collection
The number of different unique (pressure, temperature) points that calibration needs to be performed at depends
on the customer’s needs. The minimum is a 2-point calibration, and the maximum is a 5-point calibration. To
acquire raw data from the part, instruct the ZSC31010 to enter Raw Mode. This is done by issuing a Start_CM
(Start Command Mode, 5000
H
) command to the IC, followed by a Start_RM (Start Raw Mode, 4010
H
) command
with the LSB of the upper data nibble set. Now, if the Gain_B term was set to unity (800
H
) and the Gain_T term
was also set to unity (80
H
), then the part will be in Raw Mode and will be outputting raw data on its Sig™ pin,
instead of corrected bridge and temperature values. The calibration system should now collect several of these
data points (16 each of bridge and temperature is recommended) and average them. These raw bridge and
temperature measurements should be stored in the database, along with the known pressure and temperature.
The output format during Raw Mode is Bridge_High, Bridge_Low, Temp, each of these being 8-bit quantities. The
upper 2 bits of Bridge_High are zero-filled. The Temp data (8-bit only) would not really be enough data for accu-
rate temperature calibration. Therefore, the upper 3 bits of temperature information are not given, but rather
assumed known. Therefore, effectively 11 bits of temperature information are provided in this mode.
Step 3: Coefficient Calculations
The mathematical equations used to perform the coefficient calculation are quite complicated; therefore only a
basic overview is provided in section 3.6. IDT will, however, provide software to perform the coefficient calcu-
lation and the source code algorithms in a C-code format upon request. Once the coefficients are calculated, the
final step is to write them to the EEPROM of the ZSC31010.
The number of calibration points required can be as few as two or as many as five. This depends on the precision
desired, and the behavior of the resistive bridge in use.
• 2-point calibration would be used to obtain only a gain and offset term for bridge compensation with no
temperature compensation for either term.
• 3-point calibration would be used to also obtain the Tco term for 1
st
order temperature compensation of the
bridge offset term.
• 3-point calibration could also be used to obtain the additional term SOT for 2
nd
order correction for the
bridge (SOT_BR), but no temperature compensation of the bridge output; see section 3.6.2.7 for limitations.
• 4-point calibration would be used to also obtain both, the Tco term and the Tcg term, which provides
1
st
order temperature compensation of the bridge offset gain term.
• 4-point calibration could also be used to obtain the Tco term and the SOT_BR term; see section 3.6.2.7 for
limitations.
• 5-point calibration would be used to obtain Tco, Tcg, and an SOT term that provides 2
nd
order correction
applied to one and only one of the following: 2
nd
order Tco (SOT_Tco), 2
nd
order Tcg (SOT_Tcg), or
2
nd
order bridge (SOT_BR); see section 3.6.2.7 for limitations.
