Datasheet

4
UC1901
UC2901
UC3901
Figure 1. Transformer Coupled Open Loop Transfer Function
µ
µ
Note: Transformer Data: N1 = N2 = 20TAWG 26
Core = Ferroxcube 3E2A Ferrite, 0.5" O.D. toroid
Carrier Frequency = 1MHz
Figure 2. Oscillator Frequency Figure 3. Typical Driver Output Swing vs
Temperature
The error amplifier compensation terminal, Pin 12, is in-
tended as a source of feedback to the amplifier's invert-
ing input at Pin 11. For most applications, a series DC
blocking capacitor should be part of the feedback net-
work. The amplifier is internally compensated for unity
feedback.
The waveform at the driver outputs is a squarewave with
an amplitude that is proportional to the error amplifier in-
put signal. There is a fixed 12dB of gain from the error
amplifier compensation pin to the modulator driver out-
puts. The frequency of the output waveform is controlled
by either the internal oscillator or an external clock signal.
With the internal oscillator the squarewave will have a
fixed 50% duty cycle. If the internal oscillator is disabled
by connecting Pin 1, C
R
,toV
IN
then the frequency and
duty cycle of the output will be determined by the input
clock waveform at Pin 2. If the oscillator remains disabled
and there is not clock input at Pin 2, there will be a linear
12dB of signal gain to one or the other of the driver out-
puts depending on the DC state of Pin 2.
The driver outputs are emitter followers which will source
a minimum of 15mA of current. The sink current, inter-
nally limited at 700µA, can be increased by adding resis-
tors to ground at the driver outputs.
APPLICATION INFORMATION