TS3003DB datasheet(2/4 Pages) TOUCHSTONE

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TS3003 Demo Board

TS3003DB r1p0

Page 2

RTFDS

DESCRIPTION

The TS3003 requires only an RSET = 4.32MΩ

resistor to set the FOUT/PWMOUT output period to

40µs(25kHz).

With

on-board

100pF

CPWM

capacitor, the duty cycle of PWMOUT is set at

approximately 75%. Further reduction of the duty

cycle

available

with

on-

board

1MΩ

potentiometer. The complete circuit is designed at a

supply voltage of 5V and it is shown in Figure 1.

The TS3003 is a user-programmable oscillator where

the period of the square wave at its FOUT terminal is

generated by an external resistor connected to the

RSET pin. The output period is given by:

O T (

)

1 08 11

S T

Equation 1. FOUT Frequency Calculation

With

RSET

4.32M

Ω,

the

FOUT

period

approximately 40µs (25kHz) with a 50% duty cycle.

As design aids, Tables 1 lists TS3003

’s typical O T

frequency for various standard values for RSET.

The TS3003 also provides a separate PWM output

signal at its PWMOUT terminal that is anti-phase with

respect to FOUT. To adjust the pulse width of the

PWMOUT output, a single capacitor can be placed at

the CPWM pin. To determine the capacitance needed

for a desired pulse width, the following equation is to

be used:

CPWM( )

Pulse Width(s)

CPWM

00m

Equation 2. CPWM Capacitor Calculation

where ICPWM and VCPWM is the current supplied and

voltage applied to the CPWM capacitor, respectively.

The pulse width is determined based on the period of

FOUT and should never be greater than the period at

FOUT. Make sure the PWM_CNTRL pin is set to at

least 400mV when calculating the pulse width of

PWMOUT. Note VCPWM is approximately 300mV,

which is the RSET voltage. Also note that ICPWM is

approximately 1µA.

QUICK START PROCEDURE

Required Equipment

 TS3003 Demo Board

 DC Power Supply

 Oscilloscope

Model

Agilent

DSO1014A

equivalent



Two 10X, 15p //10MΩ oscilloscope probes

 Potentiometer screwdriver

To evaluate the TS3003 silicon timer, the following

steps are to be performed:

1) Before connecting the DC power supply to the

demo board, turn on the power supply, set the

DC voltage to 5V, and then turn it off.

2) Connect the DC power supply positive terminal to

the test point labeled VDD. Connect the negative

terminal of the DC power supply to the test point

labeled GND.

3) To monitor the FOUT output signal, connect the

signal terminal of an oscilloscope probe to the

test point labeled FOUT and the ground terminal

to the test point labeled GND.

4) To monitor the PWMOUT output signal, connect

the signal terminal of a second oscilloscope

probe to the test point labeled PWM_OUT and

the ground terminal to the test point labeled GND.

5) Select two channels on the oscilloscope and set

the vertical voltage scale and the vertical position

on each channel to 2V/DIV and 0V, respectively.

Set the horizontal time scale to 5µs/DIV. The

coupling should be DC coupling. Turn on the

power supply.

The supply current will vary depending on the

load on the output. Given the default set-up on

the board, the FOUT/PWMOUT output period is

approximately 40µs. The PWMOUT duty cycle is

set to approximately 75%. With an output load of

RSET (MΩ)

FOUT (kHz)

0.360

300

108

2.49

43.37

4.32

6.81

15.86

9.76

11.07

Table 1: FOUT vs RSET

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