Texas Instruments TPS3899EVM, User Manual, Page: 10 / 17

4.4 Sense and Reset Time Delay Programming (Program t
D-SENSE
and t
D
)
The TPS3899 device has two time delay programming pins. Placing a capacitor on CTS and CTR changes the
sense delay and reset delay respectively. Leaving CTS and CTR pins floating (no capacitor connected) will
cause the TPS3899 to use the default delay times of 50µs [max] for sense delay and 80µs [max] for reset delay.
Table 4-2. Sense and Reset Delay Programming with CTS and CTR Pins
t
D-SENSE
(Sense Delay, Programmed with CTS)
t
D
(Reset Delay, Programmed with CTR)
Capacitors NC 50µs [max] 80µs [max]
CTS = 0.1 µF, CTR = 0.1µF
(EVM Default)
61.94ms 61.97ms
CTS = 1 µF, CTR = 1 uF 619ms 619ms
CTS = 10 µF, CTR = 10 µF 6.19s 6.19s
The sense and reset time delay can be programmed to any value within the range by connecting a capacitor no
larger than 10µF between the corresponding CTS or CTR pin and GND. The relationship between the external
capacitors and sense and reset time delays is given by
Equation 1 and Equation 2 respectively. The
recommended maximum delay capacitor for the TPS3899 is limited to 10µF as this ensures there is enough time
for the capacitor to fully discharge when the reset condition occurs.
t
D-SENSE
= 618937 x C
CTS
+ t
D-SENSE
(no cap) (1)
(1)
t
D
= 618937 x C
CTR
+ t
D
(no cap) (2) (2)
See User-Programmable Sense and Reset Time Delay section of the TPS3899 Data Sheet for more information.
Figure 4-1 and Figure 4-2 show oscilloscope captures of sense delay and reset delay on the EVM. These
captures were taken with a shunt on J3, J4, and J5 (Rdiv [pin 3] to GND [pin 2]).
Figure 4-1. Sense Delay Oscilloscope Capture Figure 4-2. Reset Delay Oscilloscope Capture
EVM Setup and Operation www.ti.com
10 TPS3899EVM Voltage Supervisor User Guide SLVUBZ3 – SEPTEMBER 2020
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