+60°C
+55°C
OUTA
VCC
T
TRIP
+30°C
+25°C
OUTB
VCC
T
TRIP
EVM Hardware Overview and Operation
6
SNIU040 – November 2019
Copyright © 2019, Texas Instruments Incorporated
TMP392EVM User's Guide
3.3
Dual-Channel Resistor Programmable Trip Points
The application can use standard 1.05-k
Ω
to 909-k
Ω
E96-series resistors to set the hot trip point (Channel
A) and standard 10.5-k
Ω
to 909-k
Ω
E96-series resistors warm temperature trip points (Channel B). There
are 48 available trip points in the hot trip point range and 32 available trip points corresponding to a warm
trip point and hysteresis setting. The hot trip point may be in the +30°C to +124°C range, while the warm
trip point is in the +30°C to +105°C range. These settings can be found in the TMP392 device data sheet.
On the TMP392EVM, resistors R3 and R5 are populated to set the trip points for SETA and SETB,
respectively. These are located on the same breakout board where the TMP392 is located, and are
designated as RSETA and RSETB. The resistor in the SETA programs the hot trip point, while the resistor
in the SETB programs the warm trip point and the hysteresis settings for both channels. R3 is populated
on the EVM with a 9.09-k
Ω
resistor, corresponding to the hot trip point at +60°C. R5 is 90.9 k
Ω
,
corresponding to the warm trip point at +30°C and hysteresis of 5°C. With the trip point at +30°C, the user
can immediately visualize the tripped output after opening the EVM.
Two additional footprints for 0603 resistors, R4 and R6, are available to solder different resistors and
program alternate hot and warm trip points. Remember that R3 and R4 should not be populated at the
same time, and that R5 and R6 should also not be populated at the same time. Standard resistor values in
the E96-series that have 1% tolerance should be used for best performance.
shows the behavior of the output using hysteresis. When the hot trip point of +60°C is reached,
OUTA is tripped and the output will remain low until the temperature drops below the hysteresis level
subtracted from the hot threshold temperature. In this case, the hysteresis is set at 5°C, so OUTA returns
high when the temperature drops to +55°C. The same goes for the lower threshold, which is set at +30°C.
When the sensor goes to +30°C, OUTB goes low and will return high when the temperature drops to
+25°C.
Figure 5. Hysteresis Behavior Example
3.4
Manual Trip Test and Reset
Both outputs can be tripped manually by applying a logic high to the SETA and SETB inputs to evaluate
the functionality of the outputs. On the evaluation board, there are two designated push buttons—S1 and
S2—to trip OUTA and OUTB, respectively. The output LEDs for OUTA and OUTB, D3 (red) and D4
(green), will illuminate when the trip point is reached or if the output is forced by the trip test.
3.5
Open-Drain Output
Pullup resistors are located at the open-drain OUTA and OUTB outputs. TI recommends to tie the pullup
voltage to the VDD of the TMP392. If this is not possible, however, an external voltage may be used for
VDDIO that must be less than or equal to VDD + 0.3 V of the TMP392. To connect an external VDDIO,
the 0-
Ω
resistor at R7 may be desoldered to remove connection to VDD, then resoldered at R9 to connect
an external supply at TP5 as shown in