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Semtech, a supplier of analogue and mixed-signal semiconductors, has announced a sub-1 V analogue timer platform that it claims will revolutionise the conventional 555 timer for low-voltage, battery-operated small appliances. The new SX8122 offers the best-in-class battery life via its intrinsic 0.9 V operation, without the need for an external boost converter and inductor, saving board space and cost.
The SX8122 also adds low-voltage features to the legacy 555 timer, with one output that controls a DC motor or another continuous low-voltage element and another output that generates a pulse train to drive a high-brightness LED from a single battery. This combination of features makes the SX8122 ideal for a wide range of small consumer home and office appliances, such as electric toothbrushes, buzzers, toys, and LED pointers. The device also includes a voltage monitor to enable a simple USB charger for NiMH or NiCd supplied devices.
“The 555 timer is popular because it is easy to use, cost-effective and a proven performer,” said Michel Chevroulet, System Engineering Manager for Semtech’s Advanced Communications and Sensing Group. “By embedding unique low-voltage features, the SX8122 extends the versatility of the 555 timer to drive smaller size, lighter weight, and lower cost in battery-enabled consumer products. The SX8122 is the industry’s first analogue timer embedding low-voltage features for single AA/AAA cell-powered appliances.”
The new SX8122 timer operates between 0.9 V and 2 V over the full industrial temperature range of -40 to +85°C, making it ideally suited to run from one AA or AAA alkaline, NiMH or NiCd battery. The device has a continuous output that can be activated on the press of a button to control either a DC motor or other continuous low voltage function, as well as a burst output to drive a high-brightness white or green LED, or other feature requiring a voltage boost. The SX8122 timer is programmable via external resistors and a capacitor, similar to the legacy 555 analogue timer but at 1 V, and is designed for on/off button debouncing, delayed start-up functions, and analogue programmable sequencing and time-out in toys and remote control applications.
The SX8122 is battery safe. It starts controlling I/Os at 0.6 V, to eliminate unexpected behavior in the external components and prevent current drain during the start-up phase. It also features a battery overload indicator for slow NiMH or NiCd charger management. At power down (low battery), the I/Os are controlled again down to 0.6 V and the current consumption is guaranteed less than 10 µA over the full industrial temperature range to avoid battery leakage.
The SX8122 is the only single–chip, application-specific solution that operates intrinsically from 0.9 V, while managing the battery and providing precise timing. By directly providing DC and burst outputs, it can drive continuous loads, as well as loads with high threshold voltage.
Applications include a wide range of sub-1 V small consumer home and office appliances:
555-Timer/Analog Timer; Brushed DC Motor Control; Water Level Detection; Cell Phone Call Detector; Buzzer Control; LED Boost; Voltage Boost applications in products such as electric toothbrushes, shavers, automatic perfume dispensers, toys, LED pointers and LED torches.
