Author Topic: Need help in desiging 16V to 9V step down regulator circuit  (Read 3931 times)

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Offline o0tsubasa0oTopic starter

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Need help in desiging 16V to 9V step down regulator circuit
« on: March 10, 2010, 07:10:04 AM »
Hi im new to robotics and circuit . I have a project to remodify a circuit for the pervious robot into a 16.8V 4 cell battery to 9V output .


The top part of the picture is the old circuit for robot . 4 cell 16v battery to the motor driver card . 2 cell 8v battery to the mico controller chip .

The bottom part is my project , my objective is to remodify the first part of the circuit . 4cell [ 16V ] power sourice to motor and also pass through a step down regulator to the micro controller chip (output 9V ) .

i need help with designing a step down regulator circuit diagram for the 16V 4 cell battery to -> a step down regulator to -> micro controller card .

The regulator is Traco Power -> TSR 1-2490  http://singapore.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=6664376

Please help me thx .

Offline BEAMer

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Re: Need help in desiging 16V to 9V step down regulator circuit
« Reply #1 on: March 10, 2010, 07:34:56 AM »
If you are using it to power a microcontroller, then you don't necessarily require a switching regulator. A linear regulator will do. LM7809 is more than sufficient. Read the datasheet of this regulator.

BEAMer

Offline o0tsubasa0oTopic starter

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Re: Need help in desiging 16V to 9V step down regulator circuit
« Reply #2 on: March 10, 2010, 07:43:36 AM »
erm my project supervioser said i cant use linear , so i can only use a step down regulator . anyone can help me with the circuit diagrm ? thx

Offline billhowl

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Re: Need help in desiging 16V to 9V step down regulator circuit
« Reply #3 on: March 10, 2010, 09:52:07 AM »
Here is the circuit diagram.

Offline Soeren

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Re: Need help in desiging 16V to 9V step down regulator circuit
« Reply #4 on: March 10, 2010, 11:23:05 AM »
Hi,

(output 9V ) .
If the robot has got an on-board (linear) voltage regulator to go from 9V to 5V, you could remove that and select a switcher with 5V output instead. That would increase the overall efficiency.
Regards,
Sren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline o0tsubasa0oTopic starter

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Re: Need help in desiging 16V to 9V step down regulator circuit
« Reply #5 on: March 10, 2010, 06:46:39 PM »
to:billhowl  thx for ur ciruit diagram .

thx for the advices i will try them out .

Offline o0tsubasa0oTopic starter

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Re: Need help in desiging 16V to 9V step down regulator circuit
« Reply #6 on: March 10, 2010, 11:06:58 PM »
er can anyone help me with joining the regulator diagram together with the motor to form 1 circuit diagram . thx

regulator circuit diagram ->


and can anyone tell me why do i use a 47uF 25V capcitor in the regulator circuit ?

Offline Soeren

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Re: Need help in desiging 16V to 9V step down regulator circuit
« Reply #7 on: March 11, 2010, 06:23:03 PM »
Hi,

er can anyone help me with joining the regulator diagram together with the motor to form 1 circuit diagram . thx

This should do


and can anyone tell me why do i use a 47uF 25V capcitor in the regulator circuit ?

According to the datasheet, for input voltages of 32V and beyond, a 22F cap is needed, but nothing is described for less than 32V.
However, it's a good idea to have a cap in front of a voltage regulator and more so when it's a switcher taking its power in pulses, as the battery might not be able to cope and the resistance of the leads from the battery will come more into play without it.

Normally, you'd have a cap on the output as well, but since I don't know what you're gonna load it with and since it has a limit of 470F capacitive load, I haven't included one, but if you haven't got any capacity in the load, add between 10F and 50F as close to the output terminal as possible (to the ground plane), as this will reduce the output ripple (which can be up to 75mV in amplitude without a cap).

With a switcher (and anything that's electrically noisy), the capacitor should have the lowest possible ESR (Equivalent Series Resistance) and using 2 or 3 to sum up to the needed value gives a lower ESR (since each ones ESR is parallelled with the rest).

The coil L1 can be just about any coil with a good wrap of wire, the best will be powdered iron cores (yellow core) that you can find in abundance in broken PC power supplies. If you cannot find one, just use a piece of wire and live with the motor (electrical) noise remaining.
Regards,
Sren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline o0tsubasa0oTopic starter

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Re: Need help in desiging 16V to 9V step down regulator circuit
« Reply #8 on: March 11, 2010, 07:17:42 PM »
thx for helping me to understand ,i would like to know which capacitor do i need to use for the ouput, the output is connected to a 8051 microcontroller board .
« Last Edit: March 11, 2010, 07:22:30 PM by o0tsubasa0o »

Offline Soeren

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Re: Need help in desiging 16V to 9V step down regulator circuit
« Reply #9 on: March 11, 2010, 07:32:27 PM »
Hi,


If you use regular (wet) electrolytics, something between 20F and 200F should do - as before, if you 2 or 3 lesser ones, ESR and ripple will be lower.
Regards,
Sren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline o0tsubasa0oTopic starter

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Re: Need help in desiging 16V to 9V step down regulator circuit
« Reply #10 on: March 11, 2010, 08:48:38 PM »
thx :)

 


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