Datasheet MAX4165, MAX4166, MAX4167, MAX4168, MAX4169 (Analog Devices) - 10

High-Output-Drive, Precision, Low-Power, Single- Supply, Rail-to-Rail I/O Op Amps with Shutdown
INPUT VCC = +3V 0.25Vp-p MAX4165 V 0.1µF MAX4166 CC = +3V 1/2 MAX4167 MAX4167 1/2 MAX4168 100k MAX4168 4.7k MAX4169 100k R3 900k 4.7k 1µF R3 = R1 R2 100k 47Ω 32Ω 100k R1 R2 100k VCC = +3V 0.1µF Figure 4. Reducing Offset Error Due to Bias Current 1/2 MAX4167 (Noninverting) 100k 1/2 MAX4168
MAX4165–MAX4169
Figure 3. Dual MAX4167/MAX4168 Bridge Amplifier for 200mW at 3V MAX4165 MAX4166 MAX4167 MAX4168
Single-Supply Speaker Driver
MAX4169 The MAX4165/MAX4166 can be used as a single-sup- R3 ply speaker driver, as shown in the Typical Operating Circuit. Capacitor C1 is used for blocking DC (a 0.1µF ceramic capacitor can be used). When choosing resis- R3 = R1 R2 tors R3 and R4, take into consideration the input bias current as well as how much supply current can be tol- erated. Choose resistors R1 and R2 according to the amount of gain and current desired. Capacitor C3 R1 R2 ensures unity gain for DC. A 10µF electrolytic capacitor is suitable for most applications. The coupling capaci- tor C2 sets a low-frequency pole and is fairly large in Figure 5. Reducing Offset Error Due to Bias Current (Inverting) value. For a 32Ω load, a 100µF coupling capacitor gives a low-frequency pole at 50Hz. The low-frequency pole can be set according to the following equation:
Rail-to-Rail Input Stage
ƒ = 1 / 2π (RLC2) Devices in the MAX4165–MAX4169 family of high-out- put-current amplifiers have rail-to-rail input and output
Bridge Amplifier
stages designed for low-voltage, single-supply opera- The circuit shown in Figure 3 uses a dual MAX4167/ tion. The input stage consists of separate NPN and MAX4168 to implement a 3V, 200mW amplifier suitable PNP differential stages that combine to provide an for use in size-constrained applications. This configura- input common-mode range that extends 0.25V beyond tion eliminates the need for the large coupling capaci- the supply rails. The PNP stage is active for input volt- tor required by the single op-amp speaker driver when ages close to the negative rail, and the NPN stage is single-supply operation is a must. Voltage gain is set to active for input voltages near the positive rail. The +10V/V; however, it can be changed by adjusting the switchover transition region, which occurs near VCC / 2, 900kΩ resistor value. DC voltage at the speaker is limit- has been extended to minimize the slight degradation ed to 10mV. The 47Ω and 0.1µF capacitors across the in common-mode rejection ratio caused by mismatch of speaker maintain a low impedance at the load as fre- the input pairs. quency increases.
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