LB11600JV_11 Datasheet, PDF (22/30 Pages) Sanyo Semicon Device – Brushless Motor Predriver IC for Automotive Applications

LB11600JV
The time (n times the PWMIN period) required for the potential, which is increased by the V2 potential difference (ΔV)
on each input pulse, to exceed the threshold voltage (Vth = 1.25V) is the reset period (Trest).
V2 + ΔV + ΔV⋅⋅⋅ ≥ 1.25V
Trest ≤ TPWMIN × n (s)
<PWMRE Reset Time Setting Example>
VCC = 5V, PWMIN = 25kHz, on duty ratio = 20%
PWMRE: C = 2200pF, R = 180kΩ
PWMIN = 25kHz = 40μs
t1 = 40μs × 0.2 = 8μs t2 = 40μs × 0.8 = 32μs
V1 = (V0 - Ipwmre × R) × e-t1/RC + Ipwmre × R
= (0 - 200μA × 180kΩ) × 0.98 + (200μA × 180kΩ)
= - 35.28 + 36 = 0.72 (V)
V2 = V1 × e-t2/RC
= 0.72 × 0.922 = 0.664 (V)
Since ΔV (0.644) is added on each PWMIN input pulse, and
V2 + ΔV = 0.664 + 0.664 ≥ 1.25V
the threshold voltage (1.25V) will be exceeded on the second pulse.
From the formula for the on time: t1' = CR × ln ((V0 – Ipwmre × R)/(V1 - Ipwmre × R))
Since the potential difference with respect to 1.25V due to the rise potential V2 of the second PWMIN pulse is 1.25 -
0.664 = 0.586V, 1.25V will be exceeded in the on duty state. Therefore,
t1' = 2200pF × 180kΩ × ln ((0.664 – 200μA × 180kΩ) / (1.25 – 200μA × 180kΩ))
= 396μs × ln (35.336/34.75) = 6.622μs (s)
Thus the reset time Trest will be one PWMIN period plus t1'.
Trest = 40μs + 6.622μs = 46.622μs (s)
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