MPC860 Motorola, MPC860 Datasheet - Page 10

• Manufacturer Part Number: MPC860
• Description: Family Hardware Specifications
• Manufacturer: Motorola

Thermal Calculation and Measurement
Part VII Thermal Calculation and Measurement
For the following discussions, P
dissipation of the I/O drivers.
7.1
An estimation of the chip junction temperature, T
where:
The junction-to-ambient thermal resistance is an industry standard value which provides a
quick and easy estimation of thermal performance. However, the answer is only an
estimate; test cases have demonstrated that errors of a factor of two (in the quantity T
are possible.
7.2
Historically, the thermal resistance has frequently been expressed as the sum of a
junction-to-case thermal resistance and a case-to-ambient thermal resistance:
10
2
3
A(0:31), TSIZ0/REG, TSIZ1, D(0:31), DP(0:3)/IRQ(3:6), RD/WR, BURST, RSV/IRQ2, IP_B(0:1)/IWP(0:1)/
VFLS(0:1), IP_B2/IOIS16_B/AT2, IP_B3/IWP2/VF2, IP_B4/LWP0/VF0, IP_B5/LWP1/VF1, IP_B6/DSDI/AT0,
IP_B7/PTR/AT3, RXD1 /PA15, RXD2/PA13, L1TXDB/PA11, L1RXDB/PA10, L1TXDA/PA9, L1RXDA/PA8,
TIN1/L1RCLKA/BRGO1/CLK1/PA7, BRGCLK1/TOUT1/CLK2/PA6, TIN2/L1TCLKA/BRGO2/CLK3/PA5,
TOUT2/CLK4/PA4, TIN3/BRGO3/CLK5/PA3, BRGCLK2/L1RCLKB/TOUT3/CLK6/PA2, TIN4/BRGO4/CLK7/
PA1, L1TCLKB/TOUT4/CLK8/PA0, REJCT1/SPISEL/PB31, SPICLK/PB30, SPIMOSI/PB29,
BRGO4/SPIMISO/
PB28, BRGO1/I2CSDA/PB27, BRGO2/I2CSCL/PB26, SMTXD1/PB25, SMRXD1/PB24, SMSYN1/SDACK1/
PB23, SMSYN2/SDACK2/PB22, SMTXD2/L1CLKOB/PB21, SMRXD2/L1CLKOA/PB20, L1ST1/RTS1/PB19,
L1ST2/RTS2/PB18, L1ST3/L1RQB/PB17, L1ST4/L1RQA/PB16, BRGO3/PB15, RSTRT1/PB14, L1ST1/RTS1/
DREQ0/PC15, L1ST2/RTS2/DREQ1/PC14, L1ST3/L1RQB/PC13, L1ST4/L1RQA/PC12, CTS1/PC11,
TGATE1/CD1/PC10, CTS2/PC9, TGATE2/CD2/PC8, SDACK2/L1TSYNCB/PC7, L1RSYNCB/PC6, SDACK1/
L1TSYNCA/PC5, L1RSYNCA/PC4, PD15, PD14, PD13, PD12, PD11, PD10, PD9, PD8, PD5, PD6, PD7, PD4,
PD3, MII_MDC, MII_TX_ER, MII_EN, MII_MDIO, MII_TXD[0:3].
BDIP/GPL_B(5), BR, BG, FRZ/IRQ6, CS(0:5), CS(6)/CE(1)_B, CS(7)/CE(2)_B, WE0/BS_B0/IORD,
WE1/BS_B1/IOWR, WE2/BS_B2/PCOE, WE3/BS_B3/PCWE, BS_A(0:3), GPL_A0/GPL_B0, OE/GPL_A1/
GPL_B1, GPL_A(2:3)/GPL_B(2:3)/CS(2:3), UPWAITA/GPL_A4, UPWAITB/GPL_B4, GPL_A5, ALE_A,
CE1_A, CE2_A, ALE_B/DSCK/AT1, OP(0:1), OP2/MODCK1/STS, OP3/MODCK2/DSDO, BADDR(28:30).
T
R
P
A
D
θJA
Estimation with Junction-to-Ambient Thermal
Resistance
Estimation with Junction-to-Case Thermal
Resistance
= ambient temperature (ºC)
= power dissipation in package
= package junction-to-ambient thermal resistance (ºC/W)
T
R
J
θJA
= T
= R
A
+ (R
θJC
θJA
+ R
MPC860 Family Hardware Specifications
× P
θCA
D
D
)
= (V
DD
× I
J
, in °C can be obtained from the equation:
DD
) + PI/O, where PI/O is the power
MOTOROLA
J
– T
A
)