LM9040

Contents

The LM9040 is a dual sensor interface circuit consisting of two independent sampled input differential amplifiers designed for use with conventional Lambda Oxygen Sensors. The Lambda Sensor is used for monitoring the oxygen concentration in the exhaust of gasoline engines using catalytic after treatment and will deliver a voltage signal which is dependent on the air-fuel mixture. The gain of the amplifiers are internally set and can directly convert the Lambda sensor output voltage to a level suitable for A/D conversion in a system using a 5V reference.

The input common mode voltage range of each amplifier is ±2V with respect to the IC ground pin. This will allow the IC to connect to sensors which are remotely grounded at the engine exhaust manifold or exhaust pipe.

Each amplifier is capable of independent default operation should either, or both, of the leads to a sensor become open circuited.

Noise filtering is provided by an internal switched capacitor low pass filter as part of each amplifier, and by external components.

The LM9040 is fully specified over the automotive temperature range of -40°C to +125°C and is provided in a 14-pin Small Outline surface mount package.

• Single 5V supply operation
• Common mode input voltage range of ±2V
• Differential input voltage range of 50 mV to 950 mV
• Sampled differential input
• Switched capacitor low pass filter
• Internal oscillator and V_BB generator
• Open input default operation
• Cold sensor default operation
• Low power consumption (42 mW max)
• Gain set by design and guaranteed over the operating temperature range

• Closed loop emissions control
• Catalytic converter monitoring