Electronic Components Datasheet Search |
|
SSM2211S-REEL7 Datasheet(PDF) 11 Page - Analog Devices |
|
SSM2211S-REEL7 Datasheet(HTML) 11 Page - Analog Devices |
11 / 16 page SSM2211 REV. 0 –11– To find the minimum supply voltage needed to achieve a speci- fied maximum undistorted output power, simply use Figure 43. For example, an application requires only 500 mW to be output for an 8 Ω speaker. With the speaker connected in a bridged out- put configuration, the minimum supply voltage required is 3.3 V. Shutdown Feature The SSM2211 can be put into a low power consumption shut- down mode by connecting Pin 1 to 5 V. In shutdown mode, the SSM2211 has an extremely low supply current of less than 10 nA. This makes the SSM2211 ideal for battery powered applications. Pin 1 should be connected to ground for normal operation. Connecting Pin 1 to VDD will mute the outputs and put the SSM2211 into shutdown mode. A pull-up or pull-down resistor is not required. Pin 1 should always be connected to a fixed potential, either VDD or ground, and never be left floating. Leav- ing Pin 1 unconnected could produce unpredictable results. Automatic Shutdown Sensing Circuit Figure 44 shows a circuit that can be used to automatically take the SSM2211 in and out of shutdown mode. This circuit can be set to turn the SSM2211 on when an input signal of a certain amplitude is detected. The circuit will also put the SSM2211 into its low-power shutdown mode once an input signal is not sensed within a certain amount of time. This can be useful in a variety of portable radio applications where power conservation is critical. SSM2211 VIN VDD C2 R5 R6 R1 R3 R2 D1 C1 R4 A2 R7 4 VDD VDD OP181 18 5 NOTE: ADDITIONAL PINS OMITTED FOR CLARITY R8 A1 Figure 44. Automatic Shutdown Circuit The input signal to the SSM2211 is also connected to the non- inverting terminal of A2. R1, R2, and R3 set the threshold volt- age of when the SSM2211 will be taken out of shutdown mode. D1 half-wave rectifies the output of A2, discharging C1 to ground when an input signal greater than the set threshold volt- age is detected. R4 controls the charge time of C1, which sets the time until the SSM2211 is put back into shutdown mode af- ter the input signal is no longer detected. R5 and R6 are used to establish a voltage reference point equal to half of the supply voltage. R7 and R8 set the gain of the SSM2211. D1 should be a 1N914 or equivalent diode and A2 should be a rail-to-rail output amplifier, such as an OP181 or equivalent. This will ensure that C1 will discharge sufficiently to bring the SSM2211 out of shutdown mode. To find the appropriate component values, first the gain of A2 must be determined by: A V V V MIN SY THS , = (12) Where, VSY is the single supply voltage and, VTHS is the threshold voltage. AV should be set to a minimum of 2 for the circuit to work prop- erly. Next choose R1 and set R2 to: RR A V 21 1 2 =− (13) Find R3 as: R RR RR A V 3 12 12 1 = × + − () (14) C1 can be arbitrarily set, but should be small enough to not cause A2 to become capacitively overloaded. R4 and C1 will control the shutdown rate. To prevent intermittent shutdown with low frequency input signals, the minimum time constant should be: RC f LOW 41 10 ×≥ (15) Where, fLOW is the lowest input frequency expected. Shutdown Circuit Design Example In this example a portable radio application requires the SSM2211 to be turned on when an input signal greater than 50 mV is detected. The device should return to shutdown mode within 500 ms after the input signal is no longer detected. The lowest frequency of interest is 200 Hz, and a +5 V supply is being used. The minimum gain of the shutdown circuit from Equation 12 is AV = 100. R1 is set to 100 kΩ, and using Equation 13 and Equation 14, R2 = 98 k Ω and R3 = 4.9 MΩ. C1 is set to 0.01 µF, and based on Equation 15, R4 is set to 10 MΩ. To minimize power supply current, R5 and R6 are set to 10 M Ω. The above procedure will provide an adequate starting point for the shutdown circuit. Some component values may need to be adjusted empirically to optimize performance. Turn On Popping Noise During power-up or release from shutdown mode, the midrail bypass capacitor, CB, determines the rate at which the SSM2211 starts up. By adjusting the charging time constant of CB, the start-up pop noise can be pushed into the sub-audible range, greatly reducing startup popping noise. On power-up, the midrail bypass capacitor is charged through an effective resis- tance of 25 k Ω. To minimize start-up popping, the charging time constant for CB should be greater than the charging time constant for the input coupling capacitor, CC. Ck C R BC I ×Ω > 25 (16) |
Similar Part No. - SSM2211S-REEL7 |
|
Similar Description - SSM2211S-REEL7 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |