°K =

•

•

q

k 1n(N)

∆V

(1)

Battery Measurement

VDD

VBAT

7.5kΩ

2.5kΩ

DC/DC

Converter

Battery

0.5V

to

6.0V

0.125V to 1.5V

2.7V

+

A/D

Converter

TSC2003-Q1

SBAS454 – DECEMBER 2008 ........................................................................................................................................................................................... www.ti.com

The equation to solve for °K is shown in Equation 1:

Where:

ΔV V(I91) – V(I1) (in mV)

∴ °K 2.573 × ΔV°K/mV

°C = 2.573 ×

ΔV(mV) – 273°K

NOTE:

The bias current for each diode temperature measurement is only turned on during

the acquisition mode, and, therefore, does not add any noticeable increase in power,

especially if the temperature measurement only occurs occasionally.

An added feature of the TSC2003 is the ability to monitor the battery voltage on the other side of the voltage

regulator (dc/dc converter), as shown in Figure 9. The battery voltage can vary from 0.5 V to 6 V, while the

voltage regulator maintains the voltage to the TSC2003 at 2.7 V, 3.3 V, etc. The input voltage (VBAT1 or VBAT2) is

divided down by 4 so that a 6-V battery voltage is represented as 1.5 V to the ADC. The simplifies the

multiplexer and control logic. To minimize the power consumption, the divider is only on during the sample period

which occurs after control bits C3 = 0, C2 = 0, C1 = 0, and C0 = 1 (VBAT1) or C3 = 0, C2 = 1, C1 = 0, and C0 = 1

(VBAT2) are received. See Table 1 and Table 2 for the relationship between the control bits and configuration of

the TSC2003.

Figure 9. Battery Measurement Functional Block Diagram

16

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Product Folder Link(s): TSC2003-Q1