HA16107FP Ver la hoja de datos (PDF) - Renesas Electronics
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HA16107FP Datasheet PDF : 40 Pages
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HA16107P/FP, HA16108P/FP
1. Timing in Normal Operation
Timing in these ICs is based on a triangular voltage waveform. The rising edge (leading edge) defines the deadband
time tDB. The falling edge (trailing edge) defines the ON-duty control band tON. PWM output is on in the area
within tON that is bounded above by the triangle wave VCT and error output VE/O.
The following pin outputs are related to PWM control:
CT (pin 7): triangle-wave voltage output
E/O (pin 15): error output voltage
RT2 (pin 8): ON-duty pulse output voltage
OUT (pin 2): PWM pulse output (for driving the gate of a power MOS FET)
2. Triangle Oscillator, Waveform and Frequency
The triangle oscillator in these ICs generates a triangular waveform by charging and discharging timing capacitor CT
with a constant current, as shown in the equivalent circuit. The CT charge current is:
I(CTchg) = I1 =
VREF − 2VBE
RT1
The discharge current is:
I(CTdischg) = 2I2 − I1,
where
I2 =
VREF − 2VBE
RT2
In these equations Vref (reference voltage) is typically 6.45 V, and VBE (base-emitter voltage of internal transistors)
is about 0.7 V.
The deadband time is:
tDB
=
CT × RT1 × 2V
VREF − 2VBE
+ 0.25 µs
≈ 0.4 × CT × RT1 + 0.25 µs
The ON-duty time is:
tON
=
tDB
×
RT2
2RT1 − RT2
The 0.25 µs in these equations is a correction term for internal circuit delays.
The maximum ON-duty is
Du max =
RT2
2RT1
The oscillating frequency is:
fOSC =
1
0.4 CT RT1 + 0.25 µ
1–
RT2
2RT1
+ 0.25 µ
1
=
(Hz)
0.8 CT RT12 + 0.25µ × 2RT1
2RT1 − RT2
+ 0.25 µ
When RT1 = RT2, the maximum ON-duty is 50%, and:
1
fOSC ≈ 0.8 CT RT1 + 0.25 µ × 2 + 0.25 µ
1
= 0.8 CT RT1 + 0.75 µ (Hz)
This approximation is fairly close, but it should be checked in-circuit.
Rev.4.00 Jun 15, 2005 page 6 of 39
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