MC44604_05 ONSEMI [ON Semiconductor], MC44604_05 Datasheet - Page 10

• Manufacturer Part Number: MC44604_05
• Description: High Safety Pulsed Mode Standby GreenLine TM PWM Controller
• Manufacturer: ONSEMI [ON Semiconductor]

Pin
10
12
13
14
15
16
11
1
2
3
4
5
6
7
8
9
V
V
Output
GND
Foldback Input
Overvoltage Protection
Current Sense Input
Demagnetization Detection
Standby Current Set
C
Soft−Start/D
Clamp Error Amplifier Input
E/A Out
Voltage Feedback
Standby Management
R
CC
C
T
REF
max
Name
/Voltage−Mode
This pin is the positive supply of the IC.
The output high state, V
connection to the power source, it gives the possibility to set by means of an external
resistor the output source current at a different value than the sink current.
The output current capability is suited for driving a power MOSFET. A Bipolar
transistor can also be driven for low power applications. The maximum on−time of the
duty cycle can last up to 80% of the switching period.
The ground pin is a single return typically connected back to the power source, it is
used as control and power ground.
The foldback function ensures an overload protection. Feeding the foldback input with
a portion of the V
foldback characteristic allowing a smoother startup and a sharper overload protection.
The foldback action performs an active current sense clamping reduction. Above
1.0 V the foldback input is no more active.
When the overvoltage protection pin receives a voltage greater than 17 V the device
gets disabled and requires a complete restart sequence. The overvoltage level is
programmable.
A voltage proportional to the current flowing into the power switch is connected to this
input. The PWM latch uses this information to terminate the conduction of the output
buffer when operating in current mode. A maximum level of 1.0 V allows to limit the
inductor current either in current or voltage mode of operation.
A voltage delivered by an auxiliary transformer winding provides to the
demagnetization pin an indication of the magnetization state of the flyback energy
reservoir. A zero voltage detection corresponds to a complete core demagnetization.
The demagnetization detection ensures a discontinuous mode of operation. This
function can be inhibited by connecting Pin 8 to GND.
Using an external resistor connected to this pin, the standby burst mode peak current
can be adjusted.
The normal mode oscillator frequency is programmed by the capacitor C
together with the R
generates the oscillator sawtooth.
A capacitor or a resistor or a voltage source connected to this pin can temporary or
permanently control the effective switching duty−cycle. This pin can be used as a
voltage mode control input. By connecting pin 11 to Ground, the MC44604 can be
shut down.
In normal mode, the current drawn from this pin, is used by the Error Amplifier to
perform the regulation. A 4.7 V zener diode clamps the voltage of this pin.
The error amplifier output is made available for loop compensation.
This is the inverting input of the Error Amplifier. It uses a voltage that is built up using
the current drawn from the pin 12.
This block is designed to detect the standby mode. It particularly determines if the
circuit must work in standby or in normal mode at each startup. For that, it uses an
information given by an external arrangement consisting of an opto−coupler. In
standby mode, this block makes the circuit work in the standby configuration, and the
current injected in the pin 15 is used to perform the regulation. In normal mode, this
pin is internally connected to the pin 12.
The R
precise oscillator waveform. The current range goes from 100 mA up to 500 mA.
REF
http://onsemi.com
values fixes the internal reference current which is used to perform the
MC44604
10
CC
ref
voltage (1.0 V max) establishes on the system control loop a
resistance value. C
OH
, is set by the voltage applied to this pin. With a separate
Pin Description
T
, connected between pin 10 and GND,
T
choice