Semtech - Single-Cell AA/AAA, 555-Like Analog Timer with Battery-Safe Operation

“The 555 timer is one of the most popular ICs ever, 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 analog timer embedding low-voltage features for single AA/AAA cell-powered appliances.”

The new Semtech 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 analog timer but at 1 V, and is designed for on/off button debouncing, delayed start-up functions, and analog 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.

Key Features of SX8122 555-Timer:
Single-cell operation: AA or AAA alkaline, NiMH or NiCd battery
0.9 V to 2 V operation over the full industrial temperature range (-40 to +85°C)
Battery safe operation with 0.6 V I/O control
DC motor control and boost control for high-brightness white or green LEDs
No external boost converter and inductor required
Packaging: SOIC 8-pin, lead-free, halogen-free, fully RoHS and WEEE compliant
Applications
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.

Pricing and Availability
The SX8122 (order code: SX8122ISTRT) is available immediately in production quantities and is priced at $0.36 each in 2,500-piece lots. The ordering code for starter kits is SX8122EVK. Semtech offers comprehensive design assistance, including field- and factory-based support. Data sheets, volume pricing, and delivery quotes, as well as evaluation kits and samples, are available at http://www.semtech.com/info.