HA16107P Datasheet, PDF (5/40 Pages) Hitachi Semiconductor – PWM Switching Regulator for High-performance Voltage Mode Control

HA16107P/FP, HA16108P/FP
Function and Timing Chart
Triangle Waveform and PWM Output
• Timing chart (during normal operation)
V_TH 4.2 V typ
E/O
C_T
2V_BE
V_TL 2.2 V typ
V_RT2
0V
V_IN
OUT
0V
Triangle waveform
is output to C_T pin
• Oscillator equivalent circuit
×2
×2
×2
I₁ I₁
Dead band t_ON
t_DB
9
R_T2 V_RT2
8
I₂
6
7
R_T1
C_T
2I₂
×2
0.6 V
Vref
(connected internally)
−
+
Comparator for
triangle waveform
oscillation
−
+
The ×2s are transistors whose emitter area is doubled.
I₁
=
Vref − 2V_BE
R_T1
I₂ =
Vref − 2V_BE
R_T2
t_DB =
C_T × R_T1 × 2V
Vref − 2V_BE
≈ 0.4 × C_T × R_T1 (s)
t_ON
≈
t_DB
R_T2
2R_T1 − R_T2
(s)
Du max = ^RT2
2R_T1
f_OSC
≈
1
− Du max
t_DB
(Hz)
Note: When f_OSC is high, the actual value will differ from that given by the formula due to the delay time.
Determine the correct constants after constructing a test circuit.
Rev.4.00 Jun 15, 2005 page 5 of 39