HA17524P Datasheet, PDF (6/18 Pages) Hitachi Semiconductor – Switching Regulator Controller

HA17524P/FP
Error Amplifier: Figure 2 shows error amplifier biasing, applied input voltage must be set within the range
of common-mode input voltage (1.8 V to 3.4 V). Inserting a resistor and capacitor between phase
compensation terminal (pin 9) and GND in series provides phase compensation.
Current Limiter: The sense amplifier threshold voltage (V_S) for the current limiter is:
V_S = V_BE (Q ) + I₁R₂ – V_BE (Q₂)
= I₁R₂
= 200 mV typ
At the current limiter sense amp shown in figure 6, when V⁺ – V^– 200 mV, Q₁ turns on, phase
compensation terminal becomes low and the output switching element is cut off.
Comp
C_T
Error
Amp
Q₁
Comparator
R₁ ^R2
I₁ ^Q2
(–)C.L. _{Sense Amp}
(+)C.L.
V–
V+
Figure 6 Current Limiter Sense Amplifier
Figure 7 shows an example of detecting current limit. The input voltage range is –0.7 V to +1.0 V; The
current limit detection output is provided from GND line.
E₁
E₂
HA17524
CL(–)
R_S
CL(+)
+V_OUT
I_OS =
V_S
R_S
V_S = 200 mV
Figure 7 Current Limit Detector Example Operating Waveforms
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