TS12001

Page 8

TS12001 Rev. 1.0

allows the output of the comparator to latch to a

HIGH state under certain conditions. If LHDET is set

HIGH, the COUTPP output will switch based on the

input to the comparator. When LHDET is set LOW

and COUTPP is HIGH, COUTPP will remain HIGH

until LHDET goes HIGH. If COUTPP is initially LOW

instead, COUTPP will remain LOW until a LOW-to-

HIGH transition occurs on the COUTPP output. After

this event, COUTPP will remain HIGH and be

unresponsive to any changes at the input of the

comparator until LHDET goes HIGH. In essence, the

LHDET

pin

offers

a

LOW-to-HIGH

detection.

However, LHDET must not be left open. The open-

drain output, COUTOD, is the inverter version of the

If the SET pin is not used, it cannot be left

Comparator

The TS12001 has an internal comparator that can

eliminate supply glitches that commonly occur when

output transitions occur. In addition, the input exhibits

±10mV of internal hysteresis in order to insure clean

output switching behavior. The outputs can swing to

within 100mV of the supply rails. The COUTPP

output can source and sink 0.1mA and 0.5mA of

current. The COUTD outputs can sink 1.4mA of

Internal Reference

The TS12001’s on-board 0.58V ±4.5% reference

voltage can source and sink 0.1µA and 0.1µA of

current and can drive a capacitive load less than

50pF and greater than 50nF with a maximum

capacitive load of 250nF. The higher the capacitive

load, the lower the noise on the reference voltage

and the longer the time needed for the reference

voltage to respond and become available on the

REFOUT pin. With a 250nF capacitive load, the

response time is approximately 20ms. While also

available as a separate pin as REFOUT, the

reference is tied internally to the inverting input of the

comparator.

APPLICATIONS INFORMATION

External Voltage Detector Design

Depending on the battery voltage used and the

voltage one wishes to detect, the TS12001 can be

designed accordingly. As shown in Figure 1, R1 and

R2 can be selected based on the desired voltage to

detect. Table 1. provides R1 and R2 resistor

Voltage(V)

R1(M

Ω) R2(MΩ)

0.9

2.2

4.02

1.07

3.32

4.02

1.28

4.75

4.02

1.52

6.49

4.02

1.85

8.66

4.02

Threshold Voltages

The design equation for this circuit is shown

cause a HIGH-to-LOW transition on the output is

approximately 580mV. To design the circuit, R1

or R2 can be selected along with the desired

battery voltage to detect.

Then,

the

second

resistor

value

can

be

evaluated using the voltage divider equation

below.

R1=

A Nanopower 1.8V Core System Voltage Detector

When power supply rails sag in any system, it is

important to alert the CPU. A CPU can be used to

detect when I/O or core system voltages sag below a

prescribed threshold as shown Figure 2. In this

circuit, a 1.8V core system voltage detector is

designed around the TS12001 providing a low battery

detect signal. R1 and R2 were selected to set a SET

voltage at 582mV so that when VCORE drops below

1.77V, the TS12001 output transitions to LOW. It is

recommended to use 1% resistors for optimal

accuracy.

The

circuit

consumes

approximately

0.75µA of current when VCORE = 1.8V.

PC Board Layout and Power-Supply Bypassing

While

power-supply

bypass

capacitors

are

not

typically required, it is good engineering practice to

use 0.1uF bypass capacitors close to the device’s