SAM7 Hardware Considerations Frederic BOYER AT91 Support Group. Version 1.0 October 2006

Apr-06 ARM-Based Products Group 2 AT91SAM7 Power Supply Strategies 3.3V Single Power Supply Strategy: On-chip Voltage Regulator Used 1.8V & 3.3V Dual Power Supply Strategy: On-chip Voltage Regulator not Used and ADC used. On-chip Voltage Regulator and ADC not used.

Apr-06 ARM-Based Products Group 3 AT91SAM7 Power Supply Strategies (cont.) 3.3V Single Power Supply (On-chip Voltage Regulator Used) : Decoupling Capacitors on all Power Supplies

Apr-06 ARM-Based Products Group 4 AT91SAM7 Power Supply Strategies (cont.)  VDDIN: Voltage regulator Input and ADC (3.3V).  VDDIO: I/O lines (3.3V) and USB transceivers (SAM7S).  VDDFLASH: Flash (3.3V) and USB transceivers (SAM7X/XC/SE). 3.3V Single Power Supply (On-chip Voltage Regulator Used) : VDDIN must be connected to a decoupling/filtering capacitor to improve start-up stability and reduce source voltage drop

Apr-06 ARM-Based Products Group 5 AT91SAM7 Power Supply Strategies (cont.)  VDDOUT: Voltage regulator Output (1.8V).  VDDCORE: On-chip RC, Device and Flash logic (1.8V).  VDDPLL: Main Oscillator and PLL (1.8V). 3.3V Single Power Supply (On-chip Voltage Regulator Used) : VDDOUT must be connected to a decoupling/filtering capacitor to guarantee 1.8V stability

Apr-06 ARM-Based Products Group 6 AT91SAM7 Power Supply Strategies (cont.) 3.3V & 1.8V Dual Power Supplies (On-chip Voltage Regulator NOT Used and ADC used): Decoupling Capacitors on all Power Supplies

Apr-06 ARM-Based Products Group 7 AT91SAM7 Power Supply Strategies (cont.)  VDDIN: ADC Only (3.3V).  VDDIO: I/O lines (3.3V) and USB transceivers (SAM7S).  VDDFLASH: Flash (3.3V) and USB transceivers (SAM7X/XC/SE). 3.3V & 1.8V Dual Power Supplies (On-chip Voltage Regulator NOT Used and ADC used): VDDIN must be connected to a decoupling/filtering capacitor to improve start-up stability and reduce source voltage drop

Apr-06 ARM-Based Products Group 8 AT91SAM7 Power Supply Strategies (cont.) 3.3V & 1.8V Dual Power Supplies (On-chip Voltage Regulator NOT Used and ADC used):  VDDCORE: On-chip RC, Device and Flash (1.8V).  VDDPLL: Main Oscillator and PLL (1.8V). VDDOUT must be connected to a decoupling/filtering capacitor to prevent on-chip voltage regulator oscillations On-chip Voltage Regulator must be in Idle mode

Apr-06 ARM-Based Products Group 9 AT91SAM7 Power Supply Strategies (cont.) 3.3V & 1.8V Dual Power Supplies (On-chip Voltage Regulator and ADC NOT Used): Decoupling Capacitors on all Power Supplies

Apr-06 ARM-Based Products Group 10 AT91SAM7 Power Supply Strategies (cont.)  VDDIO: I/O lines (3.3V) and USB transceivers (SAM7S).  VDDFLASH: Flash (3.3V) and USB transceivers (SAM7X/XC/SE). 3.3V & 1.8V Dual Power Supplies (On-chip Voltage Regulator and ADC NOT Used): VDDIO must be connected to a decoupling/filtering capacitor to improve start-up stability and reduce source voltage drop VDDIN connected to GND

Apr-06 ARM-Based Products Group 11 AT91SAM7 Power Supply Strategies (cont.) 3.3V & 1.8V Dual Power Supplies (On-chip Voltage Regulator and ADC NOT Used):  VDDCORE: On-chip RC, Device and Flash (1.8V).  VDDPLL: Main Oscillator and PLL (1.8V). VDDCORE must be connected to a decoupling/filtering capacitor to improve start-up stability and reduce source voltage drop VDDOUT can be left unconnected

Apr-06 ARM-Based Products Group 12 SAM7 Typical Power Supply Pins Configuration

Apr-06 ARM-Based Products Group 13 SAM7 Power Supply Constraints 3.3V Single Power Supply:  VDDCORE (so VDDIN) slope must be superior or equal to 6V/ms. 3.3V & 1.8V Dual Power Supply:  VDDCORE slope must be superior or equal to 6V/ms.  VDDFLASH must always be superior or equal to VDDCORE. SAM7 SAM7S SAM7X SAM7S SAM7X

Apr-06 ARM-Based Products Group 14 Clock, Oscillator and PLL Crystal (Main Oscillator in Normal Mode): XIN and XOUT  Main Oscillator range: 3 to 20 MHz.  Crystal Load capacitance to check (C CRYSTAL ).  Internal Equivalent Load Capacitance (C L ) is:  11 pF (SAM7SE32).  20 pF (other SAM7).  1 kOhm resistor on XOUT only required for crystals with frequencies lower than 8 MHz.

Apr-06 ARM-Based Products Group 15 Clock, Oscillator and PLL (cont.) Crystal (Main Oscillator in Normal Mode): XIN and XOUT The crystal load capacitance (C CRYSTAL ) is the equivalent capacitor value that circuit must “show” to the crystal in order to oscillate at the target frequency. C load = C CRYSTAL - C L Example: C CRYSTAL = 20pF (SAM7S-EK, SAM7X-EK and SAM7SE-EK)  AT91SAM7SE32: 18pF external capacitors are required on XIN and XOUT. External capacitor  2*C load = 2*(C CRYSTAL - C L ) = 2*(20-11) = 18pF  Other AT91SAM7: no need to add external capacitors. (C load = 0pF).

Apr-06 ARM-Based Products Group 16 Clock, Oscillator and PLL (cont.) External Clock (Main Oscillator in Bypass Mode): XIN  External Clock Range: up to 50 MHz.  Duty Cycle: 40-60%  1.8V Square Wave signal (VDDPLL). XOUT can be left unconnected

Apr-06 ARM-Based Products Group 17 Clock, Oscillator and PLL (cont.) PLL Filter: PLLRC pin  PLL Filter calculation tool.  ATMEL_PLL_LFT_Filter_CALCULATOR_AT91_xxx.xls  3 Values necessary to compute the correct filter:  Fin: Quartz Frequency  MUL: PMC Multiplier (MUL+1)  DIV: PMC Divider (DIV)  Adjust R-C1-C2 for startup time. If PLL not used, PLLRC can be left unconnected

Apr-06 ARM-Based Products Group 18 ICE & JTAG  TDI, TCK, TMS and TDO: No internal Pull-up resistors.  Pull-up on TDI, TCK, TMS to reduce power consumption.

Apr-06 ARM-Based Products Group 19 ICE & JTAG (cont.)  JTAGSEL pin: Internal Pull-down resistor (15 kOhm).  JTAGSEL=0 (Default value): JTAG/ICE interface selected. Can be left unconnected for normal operations.  JTAGSEL=1 : must be tied to VDDIO to enter JTAG Boundary Scan.

Apr-06 ARM-Based Products Group 20 ERASE pin  Internal Pull-down resistor (15 kOhm).  ERASE=0 (Default value): no action. Can be left unconnected for normal operations.  ERASE=1 : must be tied to VDDIO to erase: Flash content GPNVM bits Security Bit  Debouncing Time (On-chip RC):  SAM7S: none (4µs)  SAM7X/XC: 200 ms  SAM7SE: 220 ms

Apr-06 ARM-Based Products Group 21 Reset POR (Power On Reset) on VDDCORE  Reset the whole system. RESET (NRST pin)  NRST is configured as output at power-up.  Internal Pull-up resistor on VDDIO for User/External Reset control:  SAM7S/X/XC: 10 kOhm  SAM7SE: 100 kOhm Can be left unconnected. No constraints on the reset pulse length (Built-in POR)

Apr-06 ARM-Based Products Group 22 TST pin  Internal Pull-down resistor (15 kOhm)  TST=0 (Default value): no action. Can be left unconnected for normal operations.  TST=1 : Product dependant Must be tied to VDDIO to enter: FFPI mode (PA0=PA1=1 and PA2=0) Or SAM-BA Boot recovery mode (PA0=PA1=PA2=1) (only for SAM7S).

Apr-06 ARM-Based Products Group 23 PIO I/O Lines  Pulled-up Input at reset:  SAM7S/X/XC: 10 kOhm  SAM7SE: 100 kOhm  4 High drive current I/O lines (16mA) Other I/O lines: 8mA  5V tolerant (SAM7S/X/XC only)  Schmitt trigger inputs (SAM7SE only)  Unused I/O: Should be configured as output driven at ‘0’, pull-up disabled to reduce power consumption.

Apr-06 ARM-Based Products Group 24 ADC If the ADC Controller is not used:  ADVREF  AD4  AD5  AD6  AD7 Should be connected to GND to reduce power consumption. Pure Analog Inputs

Apr-06 ARM-Based Products Group 25 USB (SAM7S/X/XC)  No Internal Pull-up: external circuitry necessary to enable the pull-up.  No Internal Pull-down.  Host disconnected  DDP must be disconnected (self powered design)  DDP and DDM are floating  Over consumption Solution: 330 kOhm pull-down on DDP and DDM to reduce over consumption.  Built-in Transceiver Enabled by default: may be disabled to reduce power consumption. VBUS monitoring circuitry necessary to remove the pull-up when the host switches off

Apr-06 ARM-Based Products Group 26 USB (SAM7SE)  Internal Pull-up: 1.5 kOhm pull-up (disabled by default): No need for an external pull-up circuitry !  No Internal Pull-down.  Host disconnected  DDP must be disconnected (self powered design)  DDP and DDM are floating  Over consumption Solution: 330 kOhm pull-down on DDP and DDM to reduce over consumption.  Built-in Transceiver Disabled by default. VBUS monitoring circuitry necessary to remove the pull-up when the host switches off

Apr-06 ARM-Based Products Group 27 USB If the USB Device Controller is not used, to reduce power consumption:  DDP must be:  Tied to VDDIO (SAM7S).  Tied to VDDFLASH (SAM7X/XC).  Left floating (SAM7SE).  DDM must be:  Tied to GND (SAM7S/X/XC).  Left floating (SAM7SE)..

Apr-06 ARM-Based Products Group 28 SDCK pin (SAM7SE only) SDCK (SDRAM Clock)  SDCK is tied low after reset.  Output-only without pull-up and not 5V-tolerant  Maximum Output Frequency:  48.2 MHz for VDDIO from 3.0V to 3.6V  25 MHz for VDDIO from 1.65V to 1.95V SAM7SE Only !