New PWM Controllers From Cherry Semiconductor Provide Unique Bi-Directional Synchronization and Leading Edge Current Sense Blanking.EAST GREENWICH East Greenwich is the name of:
CS51221 offers full control and protection, CS51227 provides basics. Both reduce component count and board space. The CS51221 and CS51227, new voltage-mode pulse-width modulated (PWM (Pulse Width Modulation) A modulation technique that generates variable-width pulses to represent the amplitude of an analog input signal. Like its fixed-width pulse density modulation (PDM) cousin, the output switching transistor is on more of the time for a ) control ICs from Cherry Semiconductor, are designed for feed forward operation in sub 150W DC/DC power converters. The CS51221 is designed for applications requiring a full set of control and protection features, while the CS51227 is a basic device targeted at more cost sensitive applications. Both controllers have all features necessary for basic voltage-mode operation. On-chip capabilities substantially reduce external component count, board area requirements, and overall power converter cost. The full-featured, 16-lead CS51221 provides programmable pulse-by-pulse overcurrent protection, overvoltage protection with programmable hysteresis hysteresis (hĭs'tərē`sĭs), phenomenon in which the response of a physical system to an external influence depends not only on the present magnitude of that influence but also on the previous history of the system. , undervoltage lockout lockout, intentional closing up of a company, factory, or shop by an employer to prevent employees from working during a strike or labor dispute. The term lockout , accurate programmable duty cycle limit, leading edge current sense blanking, and bi-directional synchronization. It offers a soft start feature for controlled start up of the output voltage and to protect against voltage overshoots. The synchronization output (SYNC) can be used to synchronize the device to other power supplies. Its bi-directional capability allows each supply to be either the master or slave unit. The 8-lead CS51227 offers fewer options, but still contains many of the control capabilities required for supply operation: undervoltage lockout, leading edge current sense blanking, and 50ns shutdown propagation delay The time it takes to transmit a signal from one place to another. Propagation delay is dependent solely on distance and two thirds the speed of light. Signals going through a wire or fiber generally travel at two thirds the speed of light. Contrast with nodal processing delay. . Leading edge current sense blanking prevents voltage spikes from causing false current limit triggering. The CS51221 and CS51227 are fixed frequency, 1 MHz (MegaHertZ) One million cycles per second. It is used to measure the transmission speed of electronic devices, including channels, buses and the computer's internal clock. A one-megahertz clock (1 MHz) means some number of bits (16, 32, 64, etc. devices that drive an external power MOSFET A Power MOSFET is a specific type of Metal Oxide Semiconductor Field-Effect Transistor (MOSFET) designed to handle large powers. Compared to the other power semiconductor devices (IGBT, Thyristor... switch with up to 1A of sink/source gate drive current. Both have a thermal shutdown feature to protect against device failure, and fast gate drive output rise and fall times (25ns into a 1nF load). Start up current is 75 microamps, up to 20V supply operation, and typical start/stop voltage thresholds of 4.6V and 3.7V respectively. Both chips are rated for a temperature range of -40(degree)C to +85(degree)C. The CS51221 is offered in a plastic 16-lead small outline (SO) narrow or a plastic 16-lead standard dual-in-line package. The CS51227 comes in an 8-lead plastic SO narrow dual-in-line package. In 10,000 piece quantities, the CS51221 is priced at $1.54 each, the CS51227 at $1.45 each. Data sheets and samples can be requested via Cherry Semiconductor's website, http://www.cherry-semi.com. Reference designs, demonstration kits and samples are available to qualified individuals through local sales and applications personnel. Cherry Semiconductor designs and manufactures standard, semi-custom and custom ICs for the automotive, communications, computer and power management markets worldwide. As both a QS 9000 and ISO (1) See ISO speed. (2) (International Organization for Standardization, Geneva, Switzerland, www.iso.ch) An organization that sets international standards, founded in 1946. The U.S. member body is ANSI. 9000 certified facility, Cherry Semiconductor pursues a corporate quality goal of 2.0 defects per billion on all new product. Cherry Semiconductor is a wholly owned subsidiary Wholly Owned Subsidiary A subsidiary whose parent company owns 100% of its common stock. Notes: In other words, the parent company owns the company outright and there are no minority owners. of The Cherry Corporation, Waukegan, Illinois. Contact: Cherry Semiconductor, 2000 South County Trail, East Greenwich, RI 02818 (USA). Phone: 1-800-272-3601. FAX: (401) 885-5786. E-mail: info@cherry- semi.com. Internet: www.cherry-semi.com |
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