Electronic Components Datasheet Search |
|
MAX44009EDT+ Datasheet(PDF) 11 Page - Maxim Integrated Products |
|
MAX44009EDT+ Datasheet(HTML) 11 Page - Maxim Integrated Products |
11 / 20 page Industry’s Lowest-Power Ambient Light Sensor with ADC 11 Applications Information Auto and Manual Modes In auto mode configuration (default setting), CDR and TIM bits are internally generated. The autoranging circuit uses two different methods to change its sensitivity. For light intensities greater than 700 lux, a current divider reduces the photodiode’s current by a factor of 8. The default, as in the previous example, is a division of 1: current goes directly into the I-to-F converter. As light intensity decreases, the autoranging circuit increases the integration time from 100ms to 200ms to 400ms, or to 800ms. The combination of the current divider and the different integration times give the A/D a range 8 times higher, as well as 8 times lower, than its nominal 16-bit range. This gives a dynamic range of 22 bits or slightly over 4,000,000 to 1. In manual mode, the user has access to 4 bits (CDR and TIM[2:0]) to override the autoranging circuitry. These affect the integration time of the A/D and the current division ratio. See the register description for manual configuration mode (0x02, bit 6). Data Format of Lux Reading The IC has a user-friendly digital output format. It con- sists of a 4-bit exponent followed by an 8-bit mantissa. In its highest sensitivity mode, 1 count represents 0.045 lux. The mantissa has a maximum value of 255, and the exponent has a maximum value of 14. This gives a maxi- mum range: 255 x 214 = 4,177,920. At 0.045 lux/LSB, the maximum lux reading is 188,000 lux. Any reading greater than that (i.e., exponent = 15) is considered to be an overload. No conversion formulas are needed as in the case of dual-diode ambient light sensors. The IC’s output (registers 0x03 and 0x04) comprises a 12-bit result that represents the ambient light expressed in units of lux. Here is how lux is calculated: Lux = (2(exponent) x mantissa) x 0.045 The exponent is a 4-bit number ranging from 0000 to 1110 (zero to 14). The mantissa is an 8-bit number ranging from 0000 0000 to 1111 1111 (zero to 255). If the INTE bit = 1 and the ambient light level exceed either threshold limit for a time longer than that specified by the Threshold Timer register, then the INTS bit is set to 1 and the INT pin is pulled low. The value in this register sets the time used to control this delay. A value of 0x00 in this register (with INTE bit = 1 in the Interrupt Enable register) configures the IC to assert the interrupt pin as soon as the light level exceeds either threshold. Time delay = (128xT7 + 64xT6 + 32xT5 + 16xT4 + 8xT3 + 4xT2 + 2xT1 + T0) x 100ms. Threshold Timer Register 0x07 The Lower Threshold High-Byte register exponent with the four most significant bits of the mantissa sets the lower trip level for interrupt functionality. This lower limit is relevant only if the INTE bit in the Interrupt Enable register is set. If the lux level is below this light level for a time greater than that specified in the Threshold Timer register, the INTS bit in the Interrupt Status register is set and the INT pin is pulled low. Mantissa (LM[7:4]): Four most significant bits of mantissa lower threshold Exponent (LE[3:0]): Exponent bits lower threshold Lower lux threshold = 2(exponent) x mantissa x 0.045 Exponent = 8xLE3 + 4xLE2 + 2xLE1 + LE0 Mantissa = 128xLM7 + 64xLM6 + 32xLM5 + 16xLM4 Lower Threshold High-Byte Register 0x06 BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 REGISTER ADDRESS LE3 LE2 LE1 LE0 LM7 LM6 LM5 LM4 0x06 BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 REGISTER ADDRESS T7 T6 T5 T4 T3 T2 T1 T0 0x07 |
Similar Part No. - MAX44009EDT+ |
|
Similar Description - MAX44009EDT+ |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | 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 |