IS61QDB42M18-250M3L datasheet, PDF

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IS61QDB42M18-250M3L: DescriptionSRAM 36M (2Mx18) 250Mhz QUAD Sync SRAM; Categorystorage; File Size609KB，30 Pages; ManufacturerISSI(Integrated Silicon Solution Inc.); Websitehttp://www.issi.com/; Environmental Compliance

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IS61QDB42M18-250M3L Overview

SRAM 36M (2Mx18) 250Mhz QUAD Sync SRAM

IS61QDB42M18-250M3L Parametric

Parameter Name	Attribute value
Product Attribute	Attribute Value
Manufacturer	ISSI(Integrated Silicon Solution Inc.)
Product Category	SRAM
RoHS	Details
Memory Size	36 Mbit
Organization	2 M x 18
Access Time	8.4 ns
Maximum Clock Frequency	250 MHz
Interface Type	Parallel
Supply Voltage - Max	1.89 V
Supply Voltage - Min	1.71 V
Supply Current - Max	650 mA
Minimum Operating Temperature	0 C
Maximum Operating Temperature	+ 70 C
Mounting Style	SMD/SMT
Package / Case	FBGA-165
Packaging	Tray
Memory Type	QDR
Type	Synchronous
Moisture Sensitive	Yes
Factory Pack Quantity	105

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IS61QDB42M18A

IS61QDB41M36A

2Mx18, 1Mx36

36Mb QUAD (Burst 4) SYNCHRONOUS SRAM

FEATURES



1Mx36 and 2Mx18 configuration available.

On-chip Delay-Locked Loop (DLL) for wide data

valid window.

Separate independent read and write ports with

concurrent read and write operations.

Synchronous pipeline read with late write operation.

Double Data Rate (DDR) interface for read and

write input ports.

1.5 cycle read latency.

Fixed 4-bit burst for read and write operations.

Clock stop support.

Two input clocks (K and K#) for address and control

registering at rising edges only.

Two output clocks (C and C#) for data output control.

Two echo clocks (CQ and CQ#) that are delivered

simultaneously with data.

+1.8V core power supply and 1.5, 1.8V VDDQ, used

with 0.75, 0.9V VREF.

HSTL input and output levels.

Registered addresses, write and read controls, byte

writes, data in, and data outputs.

Full data coherency.

Boundary scan using limited set of JTAG 1149.1

functions.

Byte write capability.

Fine ball grid array (FBGA) package:

13mmx15mm and 15mmx17mm body size

165-ball (11 x 15) array

Programmable impedance output drivers via 5x

user-supplied precision resistor.

APRIL 2016

DESCRIPTION

The 36Mb IS61QDB41M36A and IS61QDB42M18A are

synchronous, high-performance CMOS static random access

memory (SRAM) devices. These SRAMs have separate I/Os,

eliminating the need for high-speed bus turnaround. The

rising edge of K clock initiates the read/write operation, and

all internal operations are self-timed. Refer to the

Timing

Reference Diagram for Truth Table

for a description of the

basic operations of these QUAD (Burst of 4) SRAMs.

Read and write addresses are registered on alternating rising

edges of the K clock. Reads and writes are performed in

double data rate. The following are registered internally on

the rising edge of the K clock:



Read/write address



Read enable



Write enable



Byte writes for burst addresses 1 and 3



Data-in for burst addresses 1 and 3

The following are registered on the rising edge of the K#

clock:



Byte writes for burst addresses 2 and 4



Data-in for burst addresses 2 and 4

Byte writes can change with the corresponding data-in to

enable or disable writes on a per-byte basis. An internal write

buffer enables the data-ins to be registered one cycle after

the write address. The first data-in burst is clocked one cycle

later than the write command signal, and the second burst is

timed to the following rising edge of the K# clock. Two full

clock cycles are required to complete a write operation.

During the burst read operation, the data-outs from the first

and third bursts are updated from output registers of the

second and third rising edges of the C# clock (starting 1.5

cycles later after read command). The data-outs from the

second and fourth bursts are updated with the third and

fourth rising edges of the C clock. The K and K# clocks are

used to time the data-outs whenever the C and C# clocks are

tied high. Two full clock cycles are required to complete a

read operation.

The device is operated with a single +1.8V power supply and

is compatible with HSTL I/O interfaces.



without notice. ISSI assumes no liability arising out of the application or use of any information, products or services described herein. Customers are advised to

obtain the latest version of this device specification before relying on any published information and before placing orders for products.

Integrated Silicon Solution, Inc. does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can

reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such

applications unless Integrated Silicon Solution, Inc. receives written assurance to its satisfaction, that:

a.) the risk of injury or damage has been minimized;

b.) the user assume all such risks; and

c.) potential liability of Integrated Silicon Solution, Inc is adequately protected under the circumstances

Integrated Silicon Solution, Inc.- www.issi.com

Rev. B1

4/26/2016

IS61QDB42M18A

IS61QDB41M36A

Ball Descriptions

Symbol

K, K#

Type

Input

Description

Input clock: This input clock pair registers address and control inputs on the rising edge of K, and

registers data on the rising edge of K and the rising edge of K#. K# is ideally 180 degrees out of

phase with K. All synchronous inputs must meet setup and hold times around the clock rising edges.

These balls cannot remain VREF level.

Input clock for output data. C and C# are used to clock out the READ data. They can be used

together to deskew the flight times of various devices on the board back to the controller. See

application example for further details.

Synchronous echo clock outputs: The edges of these outputs are tightly matched to the

synchronous data outputs and can be used as a data valid indication. These signals are free running

clocks and do not stop when Q tri-states.

DLL disable and reset input : when low, this input causes the DLL to be bypassed and reset the

previous DLL information. When high, DLL will start operating and lock the frequency after tCK lock

time. The device behaves in one read latency mode when the DLL is turned off. In this mode, the

device can be operated at a frequency of up to 167 MHz.

Synchronous address inputs: These inputs are registered and must meet the setup and hold times

around the rising edge of K. These inputs are ignored when device is deselected.

Synchronous data inputs: Input data must meet setup and hold times around the rising edges of K

and K# during WRITE operations. See BALL CONFIGURATION figures for ball site location of

individual signals.

The x18 device uses D0~D17. D18~D35 should be treated as NC pin.

The x36 device uses D0~D35.

Synchronous data outputs: Output data is synchronized to the respective C and C#, or to the

respective K and K# if C and /C are tied to high. This bus operates in response to R# commands.

See BALL CONFIGURATION figures for ball site location of individual signals.

The x18 device uses Q0~Q17. Q18~Q35 should be treated as NC pin.

The x36 device uses Q0~Q35.

Synchronous write: When low, this input causes the address inputs to be registered and a WRITE

cycle to be initiated. This input must meet setup and hold times around the rising edge of K.

Synchronous read: When low, this input causes the address inputs to be registered and a READ

cycle to be initiated. This input must meet setup and hold times around the rising edge of K.

Synchronous byte writes: When low, these inputs cause their respective byte to be registered and

written during WRITE cycles. These signals are sampled on the same edge as the corresponding

data and must meet setup and hold times around the rising edges of K and #K for each of the two

rising edges comprising the WRITE cycle. See Write Truth Table for signal to data relationship.

HSTL input reference voltage: Nominally VDDQ/2, but may be adjusted to improve system noise

margin. Provides a reference voltage for the HSTL input buffers.

Power supply: 1.8 V nominal. See DC Characteristics and Operating Conditions for range.

Power supply: Isolated output buffer supply. Nominally 1.5 V. See DC Characteristics and Operating

Conditions for range.

Ground of the device

Output impedance matching input: This input is used to tune the device outputs to the system data

bus impedance. Q and CQ output impedance are set to 0.2xRQ, where RQ is a resistor from this

ball to ground. This ball can be connected directly to VDDQ, which enables the minimum impedance

mode. This ball cannot be connected directly to VSS or left unconnected.

IEEE1149.1 input pins for JTAG.

IEEE1149.1 output pins for JTAG.

No connect: These signals should be left floating or connected to ground to improve package heat

dissipation.

C, C#

Input

CQ, CQ#

Output

Doff#

Input

D0 - Dn

Input

Q0 - Qn

Output

Input

reference

Power

Ground

REF

DDQ

TMS, TDI,

TCK

TDO

Input

Output

N/A

Integrated Silicon Solution, Inc.- www.issi.com

Rev. B1

4/26/2016

IS61QDB42M18A

IS61QDB41M36A

The data-in provided for writing is initially kept in write buffers. The information in these buffers is written into the array

on the third write cycle. A read cycle to the last two write addresses produces data from the write buffers. The SRAM

maintains data coherency.

During a write, the byte writes independently control which byte of any of the four burst addresses is written (see

X18/X36 Write Truth Tables

and

Timing Reference Diagram for Truth Table).

Whenever a write is disabled (W# is high at the rising edge of K), data is not written into the memory.

RQ Programmable Impedance

An external resistor, RQ, must be connected between the ZQ pin on the SRAM and V

to enable the SRAM to adjust

its output driver impedance. The value of RQ must be 5x the value of the intended line impedance driven by the

SRAM. For example, an RQ of 250Ω results in a driver impedance of 50Ω. The allowable range of RQ to guarantee

impedance matching is between 175Ω and 350Ω at V

DDQ

=1.5V. The RQ resistor should be placed less than two inches

away from the ZQ ball on the SRAM module. The capacitance of the loaded ZQ trace must be less than 7.5pF.

The ZQ pin can also be directly connected to V

DDQ

to obtain a minimum impedance setting. ZQ should not be

connected to V

Programmable Impedance and Power-Up Requirements

Periodic readjustment of the output driver impedance is necessary as the impedance is greatly affected by drifts in

supply voltage and temperature. During power-up, the driver impedance is in the middle of allowable impedances

values. The final impedance value is achieved within 1024 clock cycles.

Clock Consideration

This device uses an internal DLL for maximum output data valid window. It can be placed in a stopped-clock mode to

minimize power and requires only 1024 cycles to restart.

No clocks can be issued until V

reaches its allowable operating range.

Single Clock Mode

This device can be also operated in single-clock mode. In this case, C and C# are both connected high at power-up

and must never change. Under this condition, K and K# will control the output timings.

Either clock pair must have both polarities switching and must never connect to V

REF

, as they are not differential

clocks.

Depth Expansion

Separate input and output ports enable easy depth expansion, as each port can be selected and deselected

independently. Read and write operations can occur simultaneously without affecting each other. Also, all pending

read and write transactions are always completed prior to deselecting the corresponding port.

Delay Locked Loop (DLL)

Delay Locked Loop (DLL) is a new system to align the output data coincident with clock rising or falling edge to

enhance the output valid timing characteristics. It is locked to the clock frequency and is constantly adjusted to match

the clock frequency. Therefore device can have stable output over the temperature and voltage variation.

DLL has a limitation of locking range and jitter adjustment which are specified as tKHKH and tKCvar respectively in the

AC timing characteristics. In order to turn this feature off, applying logic low to the Doff# pin will bypass this. In the DLL

off mode, the device behaves with one cycle latency and a longer access time which is known in DDR-I or legacy

QUAD mode.

Integrated Silicon Solution, Inc.- www.issi.com

Rev. B1

4/26/2016

IS61QDB42M18-250M3L Related Products

	IS61QDB42M18-250M3L	IS61QDB41M36-250M3L	IS61QDB41M36A	IS61QDB42M18A-333M3I
Description	SRAM 36M (2Mx18) 250Mhz QUAD Sync SRAM	SRAM 36M (1Mx36) 250Mhz QUAD Sync SRAM	SRAM	SRAM 36Mb QUAD (Burst of QUAD Sync SRAM
Product Attribute	Attribute Value	-	Attribute Value	Attribute Value
Manufacturer	ISSI(Integrated Silicon Solution Inc.)	-	ISSI(Integrated Silicon Solution Inc.)	ISSI(Integrated Silicon Solution Inc.)
Product Category	SRAM	-	SRAM	SRAM

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