Electronic Components Datasheet Search |
|
UG42 Datasheet(PDF) 6 Page - ATMEL Corporation |
|
UG42 Datasheet(HTML) 6 Page - ATMEL Corporation |
6 / 7 page UG Series 5–6 Rev. B – 25 May. 98 Power Consumption Static Power Consumption for UG Series ULCs There are three main factors to consider: – Leakage in the core: – PLC = VDD * ICCSB * number of used gates – Leakage in inputs and tri-stated outputs: – PLIO = VDD * (IIX * N + IOZ * M) – where: N = number of inputs – M = number of tri-stated outputs – Care must be taken to include the appropriate figure for pins with pull-ups or pull-downs. In practice, the static consumption calculation is typically done to determine the standby current of a device; in this case only those pins sourcing current should be included, i.e. where VIN or VOUT = VDD. – Dc power dissipation in driving I/O buffers due to resistive loads: – In practice, the static consumption calculation is typically done to determine the standby current of a device, and under circumstances where all of the outputs are tri-stated or in input mode. So this term is zero. – Global formula for static consumption: – PSB = PLC + PLIO Dynamic Power Consumption for UG Series ULCs There are four main factors to consider: – Static power dissipation is negligible compared to dynamic and can be ignored. – Dc power dissipation in I/O buffers due to resistive loads: – P1 (mW) = VOL * Σn (DLn * IOLn) + ( VDD – VOH) * Σn (DHn * IOHn) – where: Σn is a summation over all of the outputs and I/Os. – IOLn and IOHn are the appropriate values for driver n – DLn = percentage of time n is being driven to VOL – DHn = percentage of time n is being driven to VOH – It is difficult to obtain an exact value for this factor, since it is determined primarily by external system parameters. However, in practice this can be simplified to one of two cases where the device is either driving CMOS loads or driving TTL loads. CMOS loads can be approximated as purely capacitive loads, allowing this term to be treated as zero. TTL loads source significant current in the low state, but not the high state, allowing the second summation to be ignored. If a 50% duty cycle is assumed for dynamic outputs driving TTL loads, this can be approximated as: – P1 (mW) = VOL * (Σn * IOLn/2 + Σm * IOLm) (TTL loads) – where n are dynamic outputs and m are static low outputs. – Dynamic power dissipation for the internal gates: – P2 (mW) = VDD * IDDOP * Σg (Nf * fg)/1000 – where: Nf = number of gates toggling at frequency fg – fg = clock frequency of internal logic in MHz – Note: If the actual toggle rates are not known, a rule of thumb is to assume that the average used gate is toggling at one half of the input clock frequency. – Dynamic power dissipation in the outputs: – P3 (mW) = VDD2 * Σn fn * (COUT + Cn)/1000 – where: fn = clocking frequency in MHz of output n – Cn = output load capacitance in pF of output n – COUT = output capacitance from DC Characteristics – Global formula for dynamic consumption: – P = P1 + P2 + P3 Example: Static calculation – A 100-pin ULC with 3000 used gates, 10 inputs, 20 I/Os in input mode, 40 outputs all tri-stated. No pull-ups or pull-downs. Half of the pins are at VDD, half at VSS. Input clock is not toggling. For this example only the current calculation is desired, so the VDD term in the equations is dropped. – PLC = 1 * 3000 = 3 mA – PLIO = ((10 + 20) * 5 + 40 * 5)/2 = 105 mA – PSB = 3 + 105 = 108 mA Dynamic Calculation – We take a 16-bit resettable ripple counter which is approximately 100 gates, operating at a clock frequency of 33 MHz, which gives an average clock frequency of 33 MHz/16 for each bit and each output. There are no static outputs on this device. Operation is at 5 V, and 6-mA outputs are used and loaded at 25 pF. The output buffers are driving CMOS loads. |
Similar Part No. - UG42 |
|
Similar Description - UG42 |
|
|
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 |