The TPS3895, TPS3896, TPS3897, and TPS3898 devices (TPS389x) are a family of very small supervisory circuits that monitor voltages greater than 500 mV with a 0.25% (typical) threshold accuracy and offer adjustable delay time using external capacitors. The TPS389x family also has a logic enable pin (ENABLE or ENABLE) to power on and off the output. With the TPS3895, for example, when the input voltage pin (SENSE) rises above the threshold, and the ENABLE pin is high, then the output pin (SENSE_OUT) goes high after the capacitor-adjustable delay time. When SENSE falls below the threshold or ENABLE is low, then SENSE_OUT goes low. For truth tables, see Table 1 and Table 2.
For TPS389xA versions, both SENSE and ENABLE have a capacitor-adjustable delay. The output asserts after this capacitor-adjustable delay when both SENSE and ENABLE inputs are good. The TPS389xP devices have a small, 0.2-µs propagation delay from when the enable pin asserts to when the output pin asserts, provided SENSE is above the threshold.
All devices operate from 1.7 V to 6.5 V and have a typical quiescent current of 6 µA with an open-drain output rated at 18 V. The TPS389x is available in an ultra-small USON package and is fully specified over the temperature range of TJ = –40°C to 125°C.
PART NUMBER | PACKAGE | BODY SIZE (NOM) |
---|---|---|
TPS389x | USON (6) | 1.45 mm × 1.00 mm |
Changes from A Revision (September 2011) to B Revision
DEVICE | ENABLE | OUTPUT | INPUT (SENSE) DELAY | ENABLE DELAY |
---|---|---|---|---|
TPS3895A | Active high | Active high, push-pull | Capacitor adjustable | Capacitor adjustable |
TPS3895P | Active high | Active high, push-pull | Capacitor adjustable | 0.2 µs |
TPS3896A | Active low | Active low, push-pull | Capacitor adjustable | Capacitor adjustable |
TPS3896P | Active low | Active low, push-pull | Capacitor adjustable | 0.2 µs |
TPS3897A | Active high | Active high, open drain | Capacitor adjustable | Capacitor adjustable |
TPS3897P | Active high | Active high, open drain | Capacitor adjustable | 0.2 µs |
TPS3898A | Active low | Active low, open drain | Capacitor adjustable | Capacitor adjustable |
TPS3898P | Active low | Active low, open drain | Capacitor adjustable | 0.2 µs |
PIN | I/O | DESCRIPTION | ||
---|---|---|---|---|
NAME | USON | |||
TPS3895/ TPS3897 |
TPS3896/ TPS3898 |
|||
CT | 5 | 5 | I | Capacitor-adjustable delay. The CT pin offers a user-adjustable delay time. Connecting this pin to a ground referenced capacitor sets the delay time for SENSE rising above 0.5 V to SENSE_OUT asserting (or ENABLE asserting to SENSE_OUT asserting for A version devices). tpd(r) (s) = [CCT (µF) × 4] + 40 µs |
ENABLE | 1 | — | I | Active high input. Driving ENABLE low immediately makes SENSE_OUT go low, independent of V(SENSE). With V(SENSE) already above VIT+, drive ENABLE high to make SENSE_OUT go high after the capacitor-adjustable delay time (A version) or 0.2 µs (P version). |
ENABLE | — | 1 | I | Active low input. Driving ENABLE high immediately makes SENSE_OUT go high, independent of V(SENSE). With V(SENSE) already above VIT+, drive ENABLE low to make SENSE_OUT go low after the capacitor-adjustable delay time (A version) or 0.2 µs (P version). |
GND | 2 | 2 | — | Ground |
SENSE | 3 | 3 | I | This pin is connected to the voltage that is monitored with the use of an external resistor. The output asserts after the capacitor-adjustable delay time when V(SENSE) rises above 0.5 V and ENABLE is asserted. The output deasserts after a minimal propagation delay (16 µs) when V(SENSE) falls below VIT+ – Vhys. |
SENSE_OUT | 4 | — | O | SENSE_OUT is an open-drain and push-pull output that is immediately driven low after V(SENSE) falls below (VIT+ – Vhys) or the ENABLE input is low. SENSE_OUT goes high after the capacitor-adjustable delay time when V(SENSE) is greater than VIT+ and the ENABLE pin is high. Open-drain devices (TPS3897/8) can be pulled up to 18 V independent of VCC; pullup resistors are required for these devices. |
SENSE_OUT | — | 4 | O | SENSE_OUT is an open-drain and push-pull output that is immediately driven high after V(SENSE) falls below (VIT+ – Vhys) or the ENABLE input is high. SENSE_OUT goes low after the capacitor-adjustable delay time when V(SENSE) is greater than VIT+ and the ENABLE pin is low. Open-drain devices (TPS3897/8) can be pulled up to 18 V independent of VCC; pullup resistors are required for these devices. |
VCC | 6 | 6 | I | Supply voltage input. Connect a 1.7-V to 6.5-V supply to VCC to power the device. It is good analog design practice to place a 0.1-µF ceramic capacitor close to this pin. |