Aeroflex Application Note RadHard MSI Power Dissipation April 2008 Background The purpose of this application note is to review the power consumption of Aeroflex Colorado Springs radiation-hardened, CMOS, medium scale integration product line (RadHard MSI Logic). It is important to understand the components of power consumption as related to CMOS logic devices and how each influences the power consumed by the logic. To perform a thorough power analysis it is necessary to investigate both standby power consumption and “at frequency” power consumption. This application note develops the components of CMOS logic consumption and gives examples of a power analysis. Aeroflex implements the RadHard MSI family in 1.2μm and 0.6μm CMOS technology. In a CMOS logic device, total power is composed of both a capacitive and resistive element. The resistive component accounts for input pull-up or pull-down resistors or load resistors (e.g., TTL load). The capacitive component reflects the power required to switch internal and external capacitance along with shoot through current. Shoot through current refers to the intrinsic current consumed during CMOS logic switching. For applications with long periods of switching inactivity, calculate the power dissipation using the formula P = IDDQ * VDD. Resistive Power Component: Resistor pull-up/pull-down current or TTL sink-current P = PRDY I O VO Capacitive Power Component: Switching of load capacitance 2 P = C L VDD f Switching of internal capacitance 2 P = C INT VDD f Current spiking during switching (includes shoot through current) 1 P = [VDD I DD (MAX) (t RISE + t FALL )]f 2 Where: f (Hz) is the operating frequency CL (pF) is the load capacitance CINT (pF) is the internal capacitance (eq. 1) (eq. 2) (eq. 3) (eq. 4) To make the power dissipation calculations easier, combine the power equations to generate power constants for the three major logic components: internal gates, input buffers and output drivers. Internal Gates Input Buffers PINT (eq 3 and 4) PIB (eq 3 and 4) 8.25 (µW/gate/MHz) 10.0 (µW/buffer/MHz) Output Drivers POUT (eq 2 and 4) CL = 50 pF 1.8 (8 mA) 2.0 (12 mA) (mW/driver/MHz) Note: To scale the load capacitance the POUT needs to be scaled by the corresponding change in the load capacitance. If using a 100pF load the POUT for the 8mA driver would be (2*1.8 = 3.6 mW/driver/MHz) and the 12mA driver would be (2*2.0 = 4.0mW/driver/MHz). If the load was 30pF the mW/driver/MHz would need to be scaled by 0.6, etc. Total Power Dissipation Equation: To calculate total power dissipation for a device, sum the power that internal gates, input buffers, output drivers, and TTL sink current components consume. PTOTAL = [(N INT * PINT * f INT ) + (N IB * PIB * f IB ) + (N OUT * POUT * f OUT ) + (N RES * PRES * PPRDY )] Where: NINT PINT fINT NIB PIB fIB NOUT POUT fOUT NRES PRES PRDY = Number of internal gates = Power per internal gate = Average operating frequency of the internal gates = Number of input buffers = Power per input buffer = Average operating frequency of the input buffers = Number of output drivers = Power per output driver = Average operating frequency of the output drivers = Number of TTL output sink = Power for TTL output sink current = Percent duty cycle that output buffer is sinking TTL current The power dissipation per switching output is calculated for a logic device by using the power dissipation equation PTOTAL. Table 1 contains the switching power dissipation (PSW) values for Aeroflex’s RadHard MSI family for each switching output with units of mW/MHz. The values do not include the TTL output sink power contribution (N RES * PRES * PPRDY ) . Table 1.0 RadHard MSI Power Values for each Switching Output 1,2,3, MSI Part ID UTACTS/ACS00 UTACTS/ACS02 UTACTS/ACS04 UTACTS/ACS08 UTACTS/ACS10 UTACTS/ACS11 UTACTS/ACS14 UTACTS/ACS20 UTACTS/ACS27 UTACTS/ACS34 UTACTS/ACS54 UTACTS/ACS74 UTACTS/ACS85 UTACTS/ACS86 UTACTS/ACS109 UTACTS/ACS132 UTACTS/ACS138 UTACTS/ACS139 UTACTS/ACS151 UTACTS/ACS153 UTACTS/ACS157 UTACTS/ACS163 UTACTS/ACS164 UTACTS/ACS165 UTACTS/ACS169 UTACTS/ACS190 UTACTS/ACS191 UTACTS/ACS193 UTACTS/ACS240 UTACTS/ACS244 UTACTS/ACS245 UTACTS/ACS253 UTACTS/ACS264 UTACTS/ACS273 UTACTS/ACS279 UTACTS/ACS280 UTACTS/ACS283 UTACTS/ACS365 UTACTS/ACS373 UTACTS/ACS374 UTACTS/ACS540 UTACTS/ACS541 UTACTS/ACS4002 Notes: 1. 2. 3. Description Quad 2-Input NAND Gates Quad 2-Input NOR Gates Hex Inverters Quad 2-Input AND Gates Triple 3-Input NAND Gates Triple 3-Input AND Gates Hex Inverting Schmitt Trigger Dual 4-input NAND Gates Triple 3-Input NOR Gate Hex Noninverting Buffers 4-Wide AND-OR-INVERT Gates Dual D Flip-Flops with Clear & Preset 4-Bit Comparators Quad 2-Input Exclusive OR Gates Dual J-K Flip-Flops Quad 2-Input NAND Schmitt Triggers 3- to 8-Line Decoder/Demult. Dual 2-Line to 4-Line Decoder/Mult. 1 of 8 Data Selectors/Multiplexers 8-Line to 1-Line Multiplexer 2- to 1-Line Non-inverting Multiplexer 4-Bit Synchronous Counters 8-Bit Shift Registers 8-Bit Parallel Load Shift Registers 4-Bit Up/Down Binary Counters Syn. 4-bit Up/Down Decade Counters Syn. 4-bit Up/Down Binary Counters Synchronous 4-bit Up/Down Counter Octal Three-State Buffer Octal Three-State Buffer/Line Drivers Octal Bus Transceivers, Three-State Dual 4-Input Multiplexers Look-Ahead Carry Generators Octal D-Flip-Flops with Clear Quadruple S-R Latches 9-bit Parity Generators/Checkers 4-Bit Binary Full Adders Hex Buffer/Line Driver, Three-State Octal Transparent Latches, Three-State 8-Bit, D Type Flip-Flop, Three State Inverting Octal Buffer/line Driver Non-Inverting Octal Buffer/line Driver Dual 4-Stage NOR Gates # In. 8 8 6 8 9 9 6 8 9 6 8 8 11 8 10 8 6 6 12 12 10 5 4 12 9 8 8 8 10 10 2 12 9 10 10 9 9 8 10 10 10 10 8 # Output 4 (8mA) 4 (8mA) 6 (8mA) 4 (8mA) 3 (8mA) 3 (8mA) 6 (8mA) 2 (8mA) 3 (8mA) 6 (8mA) 1 (8mA) 4 (8mA) 3 (8mA) 4 (8mA) 4 (8mA) 4 (8mA) 8 (8mA) 8 (8mA) 2 (8mA) 2 (8mA) 4 (8mA) 9 (8mA) 8 (8mA) 2 (8mA) 5 (8mA) 6 (8mA) 6 (8mA) 6 (8mA) 8 (12mA) 8 (12mA) 16 (12mA) 2 (8mA) 5 (8mA) 8 (8mA) 4 (12mA) 2 (8mA) 5 (8mA) 6 (8mA) 8 (8mA) 8 (8mA) 8 (8mA) 8 (8mA) 2 (12mA) Gates 16 16 24 16 24 24 60 32 12 0 28 80 202 16 280 96 100 76 194 112 140 238 260 332 432 300 300 300 40 8 24 120 140 244 112 164 174 16 172 244 128 4 32 PSW/Output 1.8 mW/MHz 1.8mW/MHz 1.8mW/MHz 1.8mW/MHz 1.8mW/MHz 1.8mW/MHz 1.8mW/MHz 1.8mW/MHz 1.8mW/MHz 1.8mW/MHz 1.8mW/MHz 2.1mW/MHz 2.3mW/MHz 1.8mW/MHz 2.4mW/MHz 2.0mW/MHz 1.9mW/MHz 1.8mW/MHz 2.6mW/MHz 2.3mW/MHz 2.0mW/MHz 2.0mW/MHz 2.0mW/MHz 3.2mW/MHz 2.5mW/MHz 1.8mW/MHz 1.8mW/MHz 1.8mW/MHz 2.0mW/MHz 2.0mW/MHz 2.0mW/MHz 2.3mW/MHz 2.2mW/MHz 2.0mW/MHz 2.3mW/MHz 2.5mW/MHz 2.3mW/MHz 1.8mW/MHz 1.9mW/MHz 2.0mW/MHz 1.8mW/MHz 1.8mW/MHz 2.2mW/MHz # In defines the number of inputs. # Output defines the number of outputs and drive capability. PSW/Output is the power dissipation per switching output. The power values DO NOT include the resistive power component, typically a TTL load. The power dissipation equation can be simplified to: PTOTAL = [(N INT * PINT * f INT ) + (N IB * PIB * f IB ) + (N OUT * POUT * f OUT ) + (N RES * PRES * PPRDY )] PTOTAL = [(N SWO * PSW /Output * f) + (N RES * PRES * PPRDY )] PTOTAL = [(N SWO * PSW /Output * f) + (Loads * PRDY * I OL * VOL ) + (Loads * PRDY * I OH * VDP )]] Where: NSWO is the number of switching outputs PSW/Output is the power dissipation per switching output in mW/MHz from Table 1 f is the frequency that the outputs are switching at VDP = VDD − VOH Loads = the number of Loads that are being driven, Loads = NSWO Next, an example power analysis is performed for a CMOS UT54ACS132 and a TTL UT54ACTS132 which are Quadruple 2-Input NAND Schmitt Triggers. The ACS132 analysis assumes utilization of all 4 of the outputs switching at 80MHz, driving 4 loads low 40 percent of the time. The ACTS132 analysis assumes utilization of 3 of the 4 outputs switching at 80MHz, driving 3 loads low 40 percent of the time. Power Calculations: The set up for the device is: The input/output waveforms are: Input duty cycle is 60/40, output duty cycle is 40/60 due to inversion UT54ACS132 Power V DD = 5.0V N SWO = 4 PSW / Output = 2.0mW / MHz VOL = 0.25V I OL = 100μA I OH = −100μA VOH = 4.75V Loads = 4 V DP = V DD − VOH = 5.0V − 4.75V = 0.25V PTOTAL = (4 * 2.0mW / MHz * 80MHz) + (4 * 0.4 * 100μA * 0.25V ) + (4 * 0.6 * 100μA * 0.25V ) PTOTAL = (640mW ) + (0.04mW ) + (0.06mW ) =0.6401W The increase in junction temperature can be calculated: TINCREASE = θ JC * PTOTAL TINCREASE = 20 o C / W * 0.6401W = 12.802 Cº UT54ACTS132 Power V DD = 5.0V VOL = 0.4V N SWO = 3 I OL = 8mA PSW / Output = 2.0mW / MHz I OH = −8mA Loads = 3 VOH = 3.5V V DP = V DD − VOH = 5.0V − 3.5V = 1.5V PTOTAL = (3 * 2.0mW / MHz * 80MHz) + (3 * 0.4 * 8mA * 0.4V ) + (3 * 0.6 * 8mA * 1.5V ) PTOTAL = (480mW ) + (3.84mW ) + (21.6mW ) =0.50544W The increase in junction temperature can be calculated: TINCREASE = θ JC * PTOTAL TINCREASE = 20 o C / W * 0.50544W = 10.1088 Cº