AN8014 Panasonic Semiconductor, AN8014 Datasheet - Page 8

• Manufacturer Part Number: AN8014
• Description: Step-down/ step-up/ or inverting DC-DC converter control IC
• Manufacturer: Panasonic Semiconductor

AN8014S
8
[1] Function descriptions (continued)
2. The triangular wave generator block (OSC)
3. Error amplifier block
Application Notes (continued)
V (lower limit value, V
(pin 3) and R
connected externally. The oscillator frequency f
Example) An f
frequency. As the AN8014S is used at increasingly higher frequencies, the amount of overshoot and undershoot
due to the operation delay in the triangular wave oscillator comparator increases, and discrepancies between the
values calculated as described previously and the actual values may occur.
which is externally connected to the RT pin. Therefore, note that this IC can not be used as an IC for slave when
the several ICs are operated in parallel synchronous mode.
the signal to the PWM comparator.
voltage with built-in resistors is applied to the non-inverting input. Connecting the feedback resistor and the
capacitor between the error amplifier output pin (pin 8) and the inverting input pin (pin 7) allows the arbitrary gain
setting and the phase compensation.
output sink current to as high as 110 A and 8 mA respectively.
The triangular wave which swings from approximately 1.32 V (upper limit value, V
It is possible to use the circuit in the recommended operating range of 5 kHz to 500 kHz of the oscillator
The output source currents of the AN8014S's S.C.P. and DTC pins are determined by the timing resistor R
Detecting and amplifying DC-DC converter output voltage, the error amplifier with PNP transistor input inputs
Figure 2 shows the way to connect the error amplifier.
The common-mode input voltage range is 0.1 V to 0.8 V, and a voltage obtained by dividing the reference
Startup overshooting caused by feedback delays will be suppressed by setting the output source current and
The input voltage V
R3
R4
f
I
Because V
f
V
OSC
O
OSC
IN
1.7
obtained if C
V
IN
IN
REF
V
T
t
2.59
1
REF
pin (pin 2) respectively. Oscillator frequency can be freely decided by the value of C
OSC
+ t
1
V
R
CTH
1
6
7
RT
T
2
of approximately 215 kHz will be
C
R
1
C
R
NF
NF
Error
amp.
T
OSCL
V
3
1.7
T
R
IN
CTL
2 C
is 120 pF and RT is 15 k .
4
R
R
) will be generated by connecting a timing capacitor C
and V
PWM comparator
T
4
DTC
0.4
Figure 2. Connection method of error amplifier
R
8
T
CT
0.88 V
T
[Hz]
FB
IN
(V
V
I
IN
O
CTH
to the error amplifier are obtained from the following formulas.
V
V
OUT
CHL
OSC
)
R
is obtained by the following formula;
1
R
2
R
13
2
Figure 1. Triangular oscillation waveform
Charging Discharging
t
1
T
t
2
T
and a resistor R
OSCH
Voltage regulators
) to approximately 0.44
V
V
CTL
CTH
V
T
= 0.44 V (typ.)
= 1.32 V (typ.)
OUT
R1
R2
to the C
T
and R
T
pin
T
T