PD5036 Ver la hoja de datos (PDF) - Unspecified

Número de pieza

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Fabricante

PD5036

TELEPHONE RING GENERATOR CONTROLLER

Unspecified 

Output Amplitude Reduction Mechanism

During overload conditions, t he P D5036 reduc es t he c ircuit out put

voltage, while maintaining a clean sine wave, to a level that delivers the

allowed maximum output power. The prot ection unit counts the number

of CL pul ses w hich are rec eived duri ng a s ingle hal f s ine w ave c ycle

and c ompares t he res ult t o an i nternal threshold. The numbers of CL

pulses that ex ceed t he t hreshold i ndicate overl oad c onditions.

Reduction of the output sine wave am plitude, in one s tep resolution, is

accomplished according to the following equation.

Vout peak =

VpeakNominal

×

16

Step

During norm al operating conditions, the step num ber is 16. In overload

conditions, the step number can reach 31.

The amplitude can be reduced to about half of the nominal amplitude.

In each step there will be less current limit indications.

If the overl oad i s rem oved and t here are no CL pul ses at al l, t he

amplitude will begin to rise back, step by step. Each step takes one half

of a sine wave cycle.

The OHD Out put t hat report s an overload situation is activated based

on the step number.

Reduction of the output amplitude, by more than 16 t able steps, will be

indicated by OHD change to High (“1”).

When t he prot ection uni t rai ses t he am plitude back to step 16, the

amplitude will remain at t his s tep at least a s ingle sine period and t his

line will go back to Low (“0”).

♦ High level (OHD=”1”) means the output is overloaded.

♦ Minimum pulse length = 1 sine cycle.

♦ Maximum time for Over Load det ection = ½ sine cycle time, (30mS

at 16.7Hz ringing frequency).

♦ Over load required duration, for detection = ½ sine cycle time.

This l ine c an be us eful f or overl oad probl em report s i n m edium size

ringers, and c an be us ed f or of f hook det ection i n s mall s ize ri ngers

when there are few telephones connected to one line.

Output Shut Down

If the output load of the ring generator is high, and the output amplitude

has reac hed it s m inimal lev el, an int ernal c ounter w ill s tart to count

300mS.

If t he ov erload has not been rem oved af ter 300m S, t he prot ection will

shut down the PWM for 4.86 sec.

After the shutdown period, the PD5036 will begin operating at minimum

amplitude level.

If there are still CL pulses, the internal counter will start to count 300mS

again and shut down for 4.86 sec again.

However i f t he l oad i s rem oved af ter t he s hutdown peri od, t he out put

amplitude will start to increase, step by step.

Vin

T1

PD5019

PWM OUT

CL

100 OHM

VCC

R2

1KΩ

1

R3

Vin

U1A

8 LM339

3

+

-2

4

REF

Q1

BUK 582-100 A

C18

1nF 50 V

R1

PD5036

TELEPHONE RING GENERATOR CONTROLLER

Typical current sense circuit configuration

♦ Maximum amplitude reduction/incremental

response time = ½ sine cycle time.

♦ Time for overload shut down = (8 • sine cycle time)+300mS. Max.

♦ Shut down period = 4.86Sec.

Timing accuracy is derived from the main oscillator frequency accuracy.

DETERMINING THE OUTPUT AMPLITUDE

The t opology of t he ri ng generat or i s an open loop flyback. In this

topology, the output amplitude is determined by the PWM duty cycle.

The PD5036 changes its PWM duty cycle according to an i nternal sine

wave reference table and a known mathematical transfer function.

To determine the maximum amplitude of the output sine wave, use the

following equation:

Vout rms

=

(2.773

•

n)

•

(

R1 + R2

R2

)

♦ R1 and R2 are the voltage divider resistors used in the Vin sampling

A/D.

♦ n is the winding turn ratio of the transformer.

♦ It is recommended to change t he out put vol tage am plitude by

changing R1 or R2 while using the typical rated n. A high-resolution

potentiometer can be used to obt ain t he proper res istor val ues

during the circuit design.

CHOOSING n:

1. Define the input voltage range.

2. Calculate the average input voltage according to the following

equation.

Vin mid =

Vin min+Vin max

2

3. Choose the parameter nVin according to the following table.

Parameter M

in.

Recommended

Max.

nVin

42

48

54

4. Cal culate n (winding t urns rat io) ac cording to the following

equation.

nVin (choosed from the table)

n=

Vin mid

ADJUSTING OUTPUT AMPLITUDE WITHOUT A/D

When the input voltage sampling the A /D i s not us ed (CA D_In = ”0”),

the maximum out put am plitude i s det ermined ac cording t o t he i nput

voltage and turns ratio.

Vout rms = 1.4731• n • Vin

Note: When the input vol tage s ampling A /D i s not us ed, t he CA D_In

terminal must be grounded.

PWM_Out: This is the PWM output signal. This output is capable of

directly driving a FET.

PD5036

US Patent No. 5,828,558

Patent Pending in Europe and Asia

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