HT9274 Quad Micropower Op Amp Features · · · · · · · Quad micro power op amp Wide range of supply voltage: 1.6V~5.5V High input impedance Single supply operation Low current consumption: < 5mA per amp Rail to rail output Provides both sink and source output drive capability · Common mode input extends below negative rail Pin compatible with LM324/WT274 (14-pin DIP) 14-pin DIP/SOP package · · · · Signal detectors Active filters Caller ID systems Communication systems · · Applications · · · · Battery powered system Sensor amplifier Low power gain blocks Low power comparators General Description gain, low frequency, low power applications, especially ideal for battery powered systems where mA range of standby current is essential for long battery life span. For example, in multi-standard Caller ID systems, HT9274 is ideal as a low power line signal monitor/detector, and in car alarm systems, the HT9274 is excellent for piezo vibratile detector signal amplifier application. The HT9274 is a CMOS quad micro-power operational amplifier featuring high input impedance, extremely low power, high gain and high stability. It allows common mode input voltage range which extends below the negative rail, output swings to both rails with a reasonable sink and souce capability of the output drive current. This cost-effective device is suitable for high Comparison Table ITEM Operating Operating Voltage Current Output Source Current Output Sink Current Input Bias Current GBW Max. load (To VDD or VSS) HT9274 1.6~5.5V 5mA 500mA 500mA 1pA 0.1MHz >10kW WT274 1.35~10V 9mA 16mA 2mA 1pA 0.1MHz >500kW LM324 3~32V 400mA 20mA 8mA 45nA 1MHz >2kW 1 November 23, 1999 HT9274 Block Diagram 1 O U T 4 O U T 1 IN - 4 IN - 1 IN + 4 IN + V D D V S S 2 IN + 3 IN + 2 IN - 3 IN 3 O U T 2 O U T Pin Assignment 1 O U T 1 1 4 1 IN 2 1 3 4 IN - 1 IN + 3 1 2 4 IN + 4 O U T V D D 4 1 1 V S S 2 IN + 5 1 0 3 IN + 2 IN 6 9 3 IN - 2 O U T 7 8 3 O U T H T 9 2 7 4 1 4 D IP /S O P 2 November 23, 1999 HT9274 Pin Description Pin No. Pin Name I/O Internal Connection 1 1OUT O CMOS OUT 2 1IN- I PMOS IN Inverting input pin of the op amp 1 3 1IN+ I PMOS IN Noninverting input pin of the op amp 1 4 VDD ¾ ¾ 5 2IN+ I PMOS IN Noninverting input pin of the op amp 2 6 2IN- I PMOS IN Inverting input pin of the op amp 2 7 2OUT O CMOS OUT Output pin of the op amp 2 8 3OUT O CMOS OUT Output pin of the op amp 3 9 3IN- I PMOS IN Inverting input pin of the op amp 3 10 3IN+ I PMOS IN Noninverting input pin of the op amp 3 11 VSS ¾ ¾ 12 4IN+ I PMOS IN Noninverting input pin of the op amp 4 13 4IN- I PMOS IN Inverting input pin of the op amp 4 14 4OUT O CMOS OUT Description Output pin of the op amp 1 Positive power supply Negative power supply Output pin of the op amp 4 Absolute Maximum Ratings Supply Voltage.................................-0.3V to 6V Storage Temperature.................-50°C to 125°C Input Voltage .................VSS-0.3V to VDD+0.3V Operating Temperature ..............-20°C to 75°C Note: These are stress ratings only. Stresses exceeding the range specified under "Absolute Maximum Ratings" may cause substantial damage to the device. Functional operation of this device at other conditions beyond those listed in the specification is not implied and prolonged exposure to extreme conditions may affect device reliability. 3 November 23, 1999 HT9274 Pin Description Pin No. Pin Name I/O Internal Connection 1 1OUT O CMOS OUT 2 1IN- I PMOS IN Inverting input pin of the op amp 1 3 1IN+ I PMOS IN Noninverting input pin of the op amp 1 4 VDD ¾ ¾ 5 2IN+ I PMOS IN Noninverting input pin of the op amp 2 6 2IN- I PMOS IN Inverting input pin of the op amp 2 7 2OUT O CMOS OUT Output pin of the op amp 2 8 3OUT O CMOS OUT Output pin of the op amp 3 9 3IN- I PMOS IN Inverting input pin of the op amp 3 10 3IN+ I PMOS IN Noninverting input pin of the op amp 3 11 VSS ¾ ¾ 12 4IN+ I PMOS IN Noninverting input pin of the op amp 4 13 4IN- I PMOS IN Inverting input pin of the op amp 4 14 4OUT O CMOS OUT Description Output pin of the op amp 1 Positive power supply Negative power supply Output pin of the op amp 4 4 November 23, 1999 HT9274 Functional Description Input stage Output stage The input stage of op amps are nominal PMOS differential amplifiers (see the following diagram), therefore the common mode input voltage can extend to VSS-0.6V. On the other hand the common mode input voltage has to be maintained below (VDD-1)V to keep the input device (M2 and M3) active. This implies that when using HT9274 as a voltage follower, the input as well as output active range will be limited between VSS ~ VDD-1V (approx.). Avoid applying any voltage greater than VDD+0.6V or less than VSS-0.6V to the input pins, otherwise the internal input protection devices may be damaged. The HT9274 uses push-pull CMOS configuration as the output stage of op amps to minimize low power consumption and to provide adequate output driving current. V Note that the output is an unbuffered structure, therefore the open loop gain will be affected by the load resistor since the voltage gain of this stage can be expressed as (gm5+ gm6)´RL. V V D D D D B IA S M 5 V B IA S O U T M 1 N o n in v e r tin g In F ro m D iffe r e n tia l A m p In v e r tin g In M 2 P M O S V M 3 P M O S T o O u tp u t S ta g e V M 4 S S M 5 M 6 V S S Because of the consideration for minimized power consumption, the max. output current is limited to about 400mA for both source and sink drive. This is believed to be enough for most low power systems, however it is recommended to use the load resistor of >10kW for normal applications. In case of heavy load driving, an external buffer stage using bipolar transistors is recommended. S S Since the input impedance of PMOS is inherently very high, it can directly couple to high impedance elements without loading effect. For example, coupling to ceramic transducers, integrating capacitor and resistor networks. The HT9274 is internally compensated for AC stability and capable to withstand up to a 100pF capacitive load. Actually the extremly high input impedance is its major advantage over the bipolar counterpart, in some application fields such as integrators where the input current of op amp can cause significant error, the HT9274 is a better choice than the popular LM324. 5 November 23, 1999 HT9274 Application Circuits Micro power sensor amplifier & detector V 9 1 0 2 1 8 4 5 3 S E N S O R D D D E T _ O U T 7 6 1 3 1 1 1 2 1 4 Micro power line signal monitor V 2 T IP 1 3 R IN G V D D 4 5 7 6 D E T _ O U T 1 1 B IA S Micro power line voltage monitor L IN E B A T T 4 3 1 2 D E T _ O U T 1 1 6 November 23, 1999