Regulator ICs 4-channel switching regulator controller BA9737KV The BA9737KV is a 4-channel controller that includes all of the circuits required to construct a switching regulator. The circuits on the chip include a triangular-wave oscillator, a reference voltage circuit, an error amplifier, a PWM comparator, a pseudo-totem-pole driver, and a short-circuit protection circuit. Applications Camcoders and digital still cameras etc. Features 1) The totem-pole driver can directly drive power transistors, and the on current can be set to the rating current using an external resistor. For the off current, the peak current can be set using an external capacitor. 2) Output cutoff circuit (timer latch type) for overload protection. Absolute maximum ratings (Ta = 25C) Recommended operating conditions (Ta = 25C) 412 3) Channels 2 and 3 are supplied using the internal reference voltage, and use a positive voltage only. Channels 1 and 4 are general-purpose channels, and all inputs are externally available. 4) Channels can be switched off individually or all together (STB and STB1 to STB4). 5) Dead-time control is provided for all channels, and duty limits can be used. Regulator ICs BA9737KV Block diagram 413 Regulator ICs Pin assignments Pin descriptions 414 BA9737KV Regulator ICs BA9737KV Electrical characteristics (unless otherwise noted, Ta = 25C, VCC = 6.0V, fosc = 0.45MHz, STB, STB1 to STB4 = 5V) 415 Regulator ICs Operation notes (1) Use short and wide wiring tracks for the power supply and ground to keep the mutual impedance as small as possible, and use inductors and capacitors to keep ripple to a minimum. (2) Great care has been paid to the quality of this component. However, if the absolute maximum ratings for temperature and applied voltage are exceeded, the IC may be destroyed. Since it is not possible to predict whether it will be in short mode or open mode if the IC is destroyed, if there is a chance that the maximum ratings of the IC will be exceeded, use appropriate physical protective measures (fuses etc.). External dimensions (Units: mm) 416 BA9737KV (3) Set the dead-time input voltage to 0.58V or more. (4) This IC does not use an internal circuit to generate the output on peak current, so we recommend that you connect capacitors to each end of RBIAS to externally generate the on peak current (after taking power dissipation and efficiency into consideration). In this case, there is a possibility that the output waveform may become unstable due to the current impedance, so we recommend that you connect resistors (of about 100Ω to 500Ω) in series with the off peak capacitors.