AN8016 Panasonic Semiconductor, AN8016 Datasheet - Page 11

• Manufacturer Part Number: AN8016
• Description: Single-channel 1.8-volt step-up DC-DC converter control IC
• Manufacturer: Panasonic Semiconductor

Voltage Regulators
[4] Functional descriptions
1. Reference voltage block
2. Triangular wave generator
3. Error amplifier
Application Notes (continued)
f
voltage. This reference voltage is stabilized when the supply voltage is 1.8 V or higher.
sawtooth with a peak of 0.75 V and a trough of 0.2
V using a capacitor (for the time constant) and resis-
tor connected to the OSC pin (pin 9). The oscillator
frequency can be set to any value by selecting appro-
priate values for the external capacitor and resistor,
C
the range 20 kHz to 1 MHz. The triangular wave sig-
nal is provided to the inverting input of the PWM
comparator internally to the IC. Use the formulas
below for rough calculation of the oscillator fre-
quency.
OSC
account. See the experimentally determined graph of the oscillator frequency vs. timing capacitance value
provided in the main characteristics section.
fier that detects and amplifies the DC-DC converter
output voltage, and inputs that signal to a PWM com-
parator. The 1.27 V internal reference voltage is
applied to the noninverting input. Arbitrary gain and
phase compensation can be set up by inserting a re-
sistor and capacitor in series between the error am-
plifier output pin (pin 10) and the inverting input pin
(pin 1). The output voltage V
tor-dividing the output as shown in figure 2.
T
and R
This circuit is composed of a band gap circuit, and outputs a 1.26-volt temperature compensated reference
This circuit generates a triangular wave like
Note, however, that the above formulas do not take the rapid charge time, overshoot, and undershoot into
This circuit is an npn-transistor input error ampli-
T
C
. This oscillator can provide a frequency in
T
R
T
1
ln
V
V
OSCH
OSCL
OUT
0.75
can be set by resis-
C
T
1
R
T
[Hz]
R1
R2
V
OUT
Rapid
charge
Figure 2. Connection method of error amplifier
t
1
Figure 1. Triangular oscillator waveform
IN
V
FB
OUT
Discharge
10
1
t
T
2
1.27
amplifier
Error
1.27 V
R1 R2
R2
AN8016NSH
comparator input
V
V
To the PWM
OSCH
OSCL
0.2 V
0.75 V
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