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G8MNY > TECH 03.08.26 07:24l 100 Lines 4069 Bytes #10 (0) @ WW
BID : 949_GB7CIP
Subj: Chopper Regulators
Path: JH4XSY<N3HYM<IW2OHX<PI8ZTM<CX2SA<ED1ZAC<GB7CIP
Sent: 260802/2218Z @:GB7CIP.#32.GBR.EURO #:949 [Caterham Surrey GBR] $:949_GB7C
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (Updated Jul 11)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
These can either be step down voltage or step up voltage type, with the current
doing the inverse. Efficiency can be near to 100% in some applications.
Using an inductor to store energy they transform the power to what you want.
STEP DOWN REGULATORS
These are the most common type often from unregulated DC.
FUSE ==== L1
24V>o-oﾄﾄ()))ﾄﾂﾄﾄﾄﾄﾂﾄﾄﾄﾄﾂﾄﾄﾄﾄRﾄﾄﾂﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄｿ L2 L3
550mA INPUT ｳ ｳ ｳ ﾚﾄﾄﾄﾁﾄﾄﾄﾄﾄﾄｿ___ｳ/e ==== ====
FILTER ｳ+ ｳ ｳ ｳ I dｳ T1ｳ\___())))ﾄﾂﾄ()))ﾄﾂﾄﾄﾄﾄﾂﾄﾄ>12V
=== === ﾀﾄﾄﾄｴ+ Pulse ｳ _ｳ_ ｳ ｳ ｳ 1A
ｳC1 ｳC2 ｳ Width IC ｳ /_\D1 ===C3 ｳ ===
ｳ ｳ ﾚﾄﾄﾄﾄｴc ｳ ｳ ｳ VOLTAGE ｳC4
ｳ ｳ === ﾚﾄｴr Osc Vﾃﾄﾄﾄﾄﾄ)ﾄﾄﾄﾄﾄﾄﾄﾄ)ﾄﾄﾄﾄ>POT ｳ
ｳ ｳ Coｳ Roﾀﾄﾄﾄﾄﾄﾂﾄﾄﾄﾄﾙ ｳ ｳ ｳ ｳ
0V >ﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾁﾄﾄﾄﾄﾁﾄﾄﾄﾁﾄﾄﾁﾄﾄﾄﾄﾄﾄﾄﾁﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾁﾄﾄﾄﾄﾄﾄﾄﾄﾁﾄﾄﾄﾄﾄﾄﾁﾄﾄﾄﾄﾁﾄﾄ>
The main parts are L2, T1, D1 & C3. The controls IC may have T1 & D1 internal
depending of the power rating. The IC has an variable pulse width oscillator
inside that drives the transistor.
24Vﾄｴ .-----.
ｳ ｳ ｳ ｳ
12Vﾄｴ-ｳ '-----'
ｳ ｳ
ﾀﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄ
T1 ON OFF
I ｳ .--.
ｳ _.-' `-._
ﾀﾄﾁﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄ
When T1 is on current builds up in L2, the R is a protection resistor to
monitor over current. When T1 turns off the energy stored in L2 rings down to a
high negative voltage that via D1 charges up C3. The voltage on C3/4 eventually
reaches the internal reference voltage in the IC via the voltage setting pot, &
this reduces the pulse width of T1's drive reducing the stored energy in L2.
Output current from L2 flows into the load when T1 is on & off, so current
addition occurs.
Due to the high current pulse nature of these systems input & output filters
are needed to keep these currents in the circuit and out of the external leads.
STEP UP REGULATOR
These are used alot nowadays in PCs with low voltage batteries.
fuse ==== L1 L2 ==== D1 ==== L3
12V>o-oﾄﾄ()))ﾄﾂﾄﾄﾄﾄﾂﾄﾄﾄﾄﾂﾄﾄﾄﾄﾄﾄ((((()ﾄﾄﾄﾄﾄﾄﾄﾂﾄﾄｴ>ﾃﾄﾄﾂﾄ()))ﾄﾂﾄﾄﾄﾄﾂﾄﾄ> +24V 450mA
1A INPUT ｳ ｳ ｳ ﾚﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄｿ ｳ ｳ ｳ ｳ OUTPUT
FILTER ｳ+ ｳ ｳ ｳ Pulse ｳ__ｳ/ T1 +ｳ ｳ +ｳ FILTER
=== === ﾀﾄﾄﾄｴ+ Width dｳ ｳ\e === ｳ ===
ｳC1 ｳC2 ｳ IC Iｳ____ｳ C3ｳ ｳ ｳC4
ｳ ｳ ﾚﾄﾄﾄﾄｴc ｳ ｳ ｳ VOLTAGE ｳ
ｳ ｳ === ﾚﾄｴr Osc Vﾃﾄﾄﾄﾄ)ﾄﾄﾄﾄﾄﾄﾄ)ﾄﾄﾄﾄ>POT ｳ
ｳ ｳ Coｳ Roﾀﾄﾄﾄﾄﾄﾂﾄﾄﾄﾄﾙ R ｳ ｳ ｳ
0V>ﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾁﾄﾄﾄﾄﾁﾄﾄﾄﾁﾄﾄﾁﾄﾄﾄﾄﾄﾄﾄﾁﾄﾄﾄﾄﾄﾄﾄﾄﾄﾁﾄﾄﾄﾄﾄﾄﾄﾁﾄﾄﾄﾄﾄﾄﾁﾄﾄﾄﾄﾁﾄﾄ>
The main parts are L2, T1, D1 & C3 as before. The controls IC may have T1 & D1
internal depending of the power rating. The IC has an variable pulse width
oscillator inside that drives the transistor (NPN here but could be VMOS FET
etc).
24vﾄｴ .-----.
ｳ L2 ｳ ｳ
12vﾄｴ-. ｳ ｳ
ｳ ｳ______ｳ ｳ__
ﾀﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄ
T1 ON OFF
In Out
I ｳ .- -.
ｳ _.-' ｳ `-..
ﾀﾄﾁﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄ
When T1 is on more current builds up in L2, the R is a protection resistor to
monitor over current in T1 (not the load!). When T1 turns off the energy stored
in L2 rings up to a high positive voltage that via D1 charges up C3. This
voltage eventually reaches the internal reference voltage in the IC via the
voltage setting pot, and this then reduces the pulse width of T1's drive
reducing the stored energy in L2 etc.
Output current to the load only flows when T1 is OFF, so current reduction
occurs.
Due to the high current pulse nature of these systems input & output filters
are needed to keep these currents in the circuit and out of the external leads.
Why don't U send an interesting bul?
73 de John G8MNY @ GB7CIP
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