AT28C16-T Features • • • • • • Ideal Rewriteable Attribute Memory Simple Write Operation Self-Timed Byte Writes On-chip Address and Data Latch for SRAM-like Write Operation Fast Write Cycle Time - 1 ms 5-Volt-Only Nonvolatile Writes End of Write Detection RDY/BUSY Output DATA Polling High Reliability Endurance: 100,000 Write Cycles Data Retention: 10 Years Minimum Single 5-Volt Supply for Read and Write Very Low Power 30 mA Active Current 100 µA Standby Current Description 16K (2K x 8) PCMCIA Nonvolatile Attribute Memory The AT28C16-T is the ideal nonvolatile attribute memory: it is a low power, 5-volt-only byte writeable nonvolatile memory (E2PROM). Standby current is typically less than 100 µΑ. The AT28C16-T is written like a Static RAM, eliminating complex programming algorithms. The fast write cycle times of 1 ms, allow quick card reconfiguration in-system. Data retention is specified as 10 years minimum, precluding the necessity for batteries. Three access times have been specified to allow for varying layers of buffering between the memory and the PCMCIA interface. The AT28C16-T is accessed like a Static RAM for read and write operations. During a byte write, the address and data are latched internally. Following the initiation of a write cycle, the device will go to a busy state and automatically write the latched data using an internal control timer. The device provides two methods for detecting the end of a write cycle; the RDY/BUSY output and DATA POLLING of I/O7. Pin Configurations Pin Name Function A0 - A10 Addresses CE Chip Enable OE Output Enable WE Write Enable I/O0 - I/O7 Data Inputs/Outputs RDY/BSY Ready/Busy Output NC No Connect AT28C16-T TSOP Top View 0285C 2-175 Block Diagram Absolute Maximum Ratings* Temperature Under Bias................. -55°C to +125°C Storage Temperature...................... -65°C to +125°C All Input Voltages (including NC Pins) with Respect to Ground ................... -0.6V to +6.25V All Output Voltages with Respect to Ground .............-0.6V to VCC + 0.6V Voltage on OE and A9 with Respect to Ground ................... -0.6V to +13.5V 2-176 AT28C16-T *NOTICE: Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. AT28C16-T Device Operation READ:The AT28C16-T is accessed like a Static RAM. When CE and OE are low and WE is high, the data stored at the memory location detemined by the address pins is asserted on the outputs. The outputs are put in a high impedance state whenever CE or OE is high. This dual-line control gives designers increased flexibility in preventing bus contention. BYTE WRITE: Writing data into the AT28C16-T is similar to writing into a Static RAM. A low pulse on WE or CE input with OE high and CE or WE low (respectively) initiates a byte write. The address is latched on the falling edge of WE or CE (whichever occurs last) and the data is latched on the rising edge of WE or CE (whichever occurs first). Once a byte write is started it will automatically time itself to completion. For the AT28C16-T the write cycle time is 1 ms maximum. Once a programming operation has been initiated and for the duration of tWC, a read operation will effectively be a polling operation. READY/BUSY: Pin 1 is an open drain READY/BUSY output that indicates the current status of the self-timed internal write cycle. READY/BUSY is actively pulled low during the write cycle and is released at the completion of the write. The open drain output allows OR-tying of several devices to a common interrupt input. DATA POLLING: The AT28C16-T also provides DATA polling to signal the completion of a write cycle. During a write cycle, an attempted read of the the data being written results in the complement of that data for I/O7 (the other outputs are indeterminate). When the write cycle is finished, true data appears on all ouputs. WRITE PROTECTION: Inadvertent writes to the device are protected against in the following ways: (a) VCC sense— if VCC is below 3.8V (typical) the write function is inhibited; (b) VCC power on delay— once VCC h a s reached 3.8V the device will automatically time out 5 ms (typical) before allowing a byte write; (c) Write Inhibit— holding any one of OE low, CE high or WE high inhibits byte write cycles. CHIP CLEAR: The contents of the entire memory of the AT28C16-T may be set to the high state by the Chip Clear operation. By setting CE low and OE to 12V, the chip is cleared when a 10ms low pulse is applied to WE. DEVICE IDENTIFICATION: A n e x t r a 3 2 - b y t e s o f E2PROM memory are available to the user for device identifcation. By raising A9 to 12V (± 0.5V) and using address locations 7E0H to 7FFH the additional bytes may be written to or read from in the same manner as the regular memory array. 2-177 DC and AC Operating Range AT28C16-15T Com. Operating Temperature (Case) 0°C - 70°C Ind. -40°C - 85°C 5V ± 10% VCC Power Supply Operating Modes Mode CE OE WE I/O Read VIL VIL VIH DOUT VIL VIH VIL DIN VIH (1) Write (2) Standby/Write Inhibit X X High Z Write Inhibit X X VIH Write Inhibit X VIL X Output Disable X VIH X High Z VIL High Z Chip Erase VH VIL (3) 3. VH = 12.0V ± 0.5V. Notes: 1. X can be VIL or VIH. 2. Refer to AC Programming Waveforms. DC Characteristics Symbol Parameter Condition Min Max Units ILI Input Load Current VIN = 0V to VCC + 1V 10 µA ILO Output Leakage Current VI/O = 0V to VCC 10 µA ISB1 VCC Standby Current CMOS CE = VCC - 0.3V to VCC + 1.0V 100 µA ISB2 VCC Standby Current TTL CE = 2.0V to VCC + 1.0V Com. 2 mA Ind. 3 mA ICC VCC Active Current f = 5 MHz; IOUT = 0 mA Com. 30 mA Ind. 45 mA VIL Input Low Voltage 0.8 V VIH Input High Voltage VOL Output Low Voltage IOL = 2.1 mA VOH Output High Voltage IOH = -400 µA 2-178 AT28C16-T 2.0 V .4 2.4 V V AT28C16-T AC Read Characteristics AT28C16-15T PCMCIA Symbol Atmel Symbol Parameter Min tC (R) tRC Read Cycle Time 150 tA (A) tACC tA (CE) tA (OE) tEN (CE) Units Max ns Address Access Time 150 ns tCE (1) CE Access Time 150 ns tOE (2) OE Access Time 0 75 ns Output Enable Time From CE 0 ns Output Enable Time From OE 0 ns ns tLz (4) tEN (OE) tOLZ tV (A) tOH (4) Output Hold Time 0 tDIS (CE) tDF (3, 4) Output Disable Time From CE 0 50 ns tDIS (OE) tDF (3, 4) Output Disable Time From OE 0 50 ns AC Read Waveforms (1, 2, 3, 4) Notes: 1. CE may be delayed up to tACC - tCE after the address transition without impact on tACC. 2. OE may be delayed up to tCE - tOE after the falling edge of CE without impact on tCE or by tACC - tOE after an address change without impact on tACC. 3. tDF is specified from OE or CE whichever occurs first (CL = 5 pF). 4. This parameter is characterized and is not 100% tested. Input Test Waveforms and Measurement Level Output Test Load tR, tF < 5 ns Pin Capacitance (f = 1 MHz, T = 25°C) (1) Typ Max Units CIN 4 6 pF VIN = 0V COUT 8 12 pF VOUT = 0V Note: Conditions 1. This parameter is characterized and is not 100% tested. 2-179 AC Write Characteristics PCMCIA Symbol Atmel Symbol Parameter tSU (A) tAS Address Setup Time 10 ns tSU (OE-WE) tOES Output Disable Time To WE 10 ns tSU (CE-WE) tCS Chip Enable Time To WE 0 ns tW (WE) tWP Write Enable Pulse Width 100 tSU (D-WEH) tDS Data Setup To WE High 50 ns tH (A) tAH Address Hold Time From WE 50 ns tH (D) tDH Data Hold Time From WE High 10 ns tH (OE-WE) tOEH Output Enable Hold Time From WE High 10 ns tH (CE-WE) tCH Chip Enable Hold Time From WE High 0 ns tD (B) tDB Delay From WE High To BUSY Asserted 50 ns tC (W) tWC Write Cycle Time 1 ms AC Write Waveforms 2-180 AT28C16-T Min Max 1000 Units ns AT28C16-T Data Polling Waveforms Note: 1. Data Polling AC Timing Characteristics are the same as the AC Read Characteristics. Chip Erase Waveforms tS = tH = 1 µsec (min.) tW = 10 msec (min.) VH = 12.0 ± 0.5V 2-181 Ordering Information (1) tACC ICC (mA) Ordering Code Package 0.1 AT28C16-15TC 28T Commercial (0°C to 70°C) 0.1 AT28C16-15TI 28T Industrial (-40°C to 85°C) (ns) Active Standby 150 30 45 Operation Range Notes: 1. See Valid Part Number table below. 2. The 28C16 200 ns and 250 ns speed selections have been removed from valid selections table and are replaced by the faster 150 ns TAA offering. Valid Part Numbers The following table lists standard Atmel products that can be ordered. Device Numbers AT28C16 Speed 15 Package and Temperature Combinations TC, TI Package Type 28T 2-182 28 Lead, Plastic Thin Small Outline Package (TSOP) AT28C16-T