MC34067DWR2G ON Semiconductor, MC34067DWR2G Datasheet - Page 9

• Manufacturer Part Number: MC34067DWR2G
• Description: IC CTRLR SMPS DBL END HF 16-SOIC
• Manufacturer: ON Semiconductor
• Type: Flybackr

Specifications of MC34067DWR2G

• Internal Switch(s): No
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Current - Output: 100mA
• Frequency - Switching: 525kHz ~ 2.05MHz
• Voltage - Input: 2.5 ~ 20 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (0.300", 7.5mm Width)
• Power - Output: 862mW
• Output Voltage Range: 5 V to 5.2 V
• Input Voltage Range: 20 V
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Equation 1:
through resistor R
C
by Equation 2:
and can be calculated by Equation 3:
One−Shot Timer
simultaneously providing a deadtime before either output is
enabled. The One−Shot capacitor (C
concurrently with the oscillator capacitor by transistor Q1,
as shown in Figure 16. The one−shot period begins when the
oscillator comparator turns off Q1, allowing C
discharge. The period ends when resistor R
to the threshold of the One−Shot comparator. The lower
threshold of the One−Shot is 3.6 V. By choosing C
by solved by Equation 5:
through the output drivers will affect the One−Shot period.
To guarantee accuracy, the output pulse of the control chip
is trimmed to within 5% of 250 ns with nominal values of R
and C
are OR’d together to produce the pulse t
Flip−Flop and output drivers. The output pulse (t
initiated by the Oscillator and terminated by the One−Shot
comparator. With zero voltage resonant mode converters,
the oscillator discharge time should never be set less than the
one−shot period.
where t
OSC
The minimum frequency is programmed by R
The maximum oscillator frequency is set by the current
The discharge current through R
Resistor R
The One−Shot is designed to disable both outputs
Errors in the threshold voltage and propagation delays
The outputs of the Oscillator and One−Shot comparators
I
(max)
R
T
at the maximum oscillator frequency can be calculated
I
.
OSC
R
PD
OSC
R
is the internal propagation delay.
T
=
VFO
=
C OSC
C
R
=
=
OSC
VFO
can now be calculated by Equation 4:
ƒ
C
=
5.1 − 3.6
(min)
VFO
R OSC
T
1
R OSC
1.5
. The current required to discharge
=
t
n
5.1 − 3.6
n
−
OS
ƒ
(max)
t
I (max)
PD
1
5.1
3.6
5.1
3.6
2.5 − V EAsat
ε
ε
−
−
ƒ (min)
−
=
R OSC
=
OSC
t
I R
0.348
=
ƒ
(max)
(min)
1.5C
1
0.348
OSC
R OSC
C OSC
OS
must also be known
1
t
OS
, which drives the
C OSC
−
OSC
T
T
C OSC
70 ns
) is charged
C T
discharges C
ƒ (max)
OSC
T
, R
(eq. 3)
(eq. 4)
(eq. 5)
http://onsemi.com
OS
(eq. 1)
(eq. 2)
using
T
T
) is
can
to
T
T
9
Error Amplifier
provided for feedback control of the power supply system.
The Error Amplifier is internally compensated and features
dc open loop gain greater than 70 dB, input offset voltage of
less than 10 mV and a guaranteed minimum gain−bandwidth
product of 2.5 MHz. The input common mode range extends
from 1.5 V to 5.1 V, which includes the reference voltage.
pin by R
Oscillator Control Current, I
Error Amplifier is restricted by a clamp circuit to improve
its transient recovery time.
Output Section
timer is gated to dual totem−pole output drives by the
Steering Flip−Flop shown in Figure 18. Positive transitions
of t
alternate between Output A and Output B. The flip−flop is
reset by the undervoltage lockout circuit during startup to
guarantee that the first pulse appears at Output A.
A fully accessible high performance Error Amplifier is
When the Error Amplifier output is coupled to the I
The pulse(t
OS
Figure 18. Steering Flip−Flop and Output Drivers
Noninverting Input
Error Amp Output
I
OSC
Inverting Input
toggle the Flip−Flop, which causes the pulses to
Control Current
Flip-Flop
VFO
Steering
Figure 17. Error Amplifier and Clamp
T
R
Oscillator
, as illustrated in Figure 17, it provides the
OS
Q
Q
R
), generated by the Oscillator and One−Shot
VFO
3
6
8
7
Error
Amp
OSC
PWR
GND
PWR
GND
. The output swing of the
V
V
CC
CC
14
13
12
Error Amp
Clamp
Output A
Power Ground
Output B
3.1 V
OSC