View 1536I_963032.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

Final Electrical Specifications
LTC1536 Precision Triple Supply Monitor for PCI Applications
FEATURES
s s s s s s s s s s s
DESCRIPTION
The LTC(R)1536 is designed for PCI local bus applications with multiple supply voltages that require low power, small size, high speed and high accuracy supply monitoring. For 3.3V and 5V supplies that are > 500mV below spec or for the condition when the 5V supply falls below the 3.3V supply, the LTC1536 has a very fast response time capable of meeting the PCI tFAIL timing specification. Tight 0.75% threshold accuracy and glitch immunity ensure reliable reset operation without false triggering. The RST output is guaranteed to be in the correct state for VCC5 or VCC3 down to 1V. The 100A typical supply current makes the LTC1536 ideal for power-conscious systems. A manual pushbutton reset input provides the ability to generate a very narrow "soft" reset pulse (100s typ) or a 200ms reset pulse equivalent to a power-on reset. Both SRST and RST outputs are open-drain and can be OR-tied with other reset sources.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Simultaneously Monitors 5V, 3.3V and Adjustable Inputs Guaranteed Threshold Accuracy: 0.75% Low Supply Current: 100A Internal Reset Time Delay: 200ms Manual Pushbutton Reset Input Active Low and Active High Reset Outputs Active Low "Soft" Reset Output Power Supply Glitch Immunity Guaranteed Reset for Either VCC3 1V or VCC5 1V Meets PCI tFAIL Timing Specifications Rev 2.1 8-Pin SO and MSOP Packages
APPLICATIONS
s s s s s s
PCI-Based Systems Desktop Computers Notebook Computers Intelligent Instruments Portable Battery-Powered Equipment Network Servers
TYPICAL APPLICATION
PCI RST Generation
3.3V 0.3V 0.1F 1 5V 5% 2 3 4 0.1F LTC1536 VCC3 VCC5 VCCA GND PBR SRST RST RST 8 7 6 5 RST
VOLTAGE (1V/DIV)
PUSHBUTTON RESET
RPU
5
PCI LOCAL BUS
4 3 2
PWR GOOD
RPU SELECTED TO MEET RISE TIME SLEW RATE REQUIREMENTS (1k MIN)
1
1536 TA01
0
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
U
U
U
Power Fail Waveform 5V Dropping Below 3.3V by 300mV
VCC5 = 5V TO 3V STEP VCC3 = VCCA = 3.3V 4.7k PULL-UP FROM RST TO VCC3 VCC5
RST
TIME (20ns/DIV)
1536 TA02
1
LTC1536 ABSOLUTE
(Notes 1, 2)
AXI U
RATI GS
Operating Temperature Range ................... 0C to 70C Storage Temperature Range ................ - 65C to 150C Lead Temperature (Soldering, 10 sec)................. 300C
Terminal Voltage VCC3, VCC5, VCCA .................................... - 0.3V to 7V RST, SRST ............................................ - 0.3V to 7V RST ......................................... - 0.3V to VCC3 + 0.3V PBR .......................................................... - 7V to 7V
PACKAGE/ORDER I FOR ATIO
TOP VIEW VCC3 VCC5 VCCA GND 1 2 3 4 8 7 6 5 PBR SRST RST RST
ORDER PART NUMBER LTC1536CMS8 MS8 PART NUMBER LTBV
MS8 PACKAGE 8-LEAD PLASTIC MSOP
TJMAX = 125C, JA = 160C/ W
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
VCC3 = 3.3V, VCC5 = 5V, VCCA = VCC3, TA = 25C unless otherwise noted.
SYMBOL VRT3 VRT5 VRTA VCC IVCC3 IVCC5 IVCCA tRST tSRST tUV PARAMETER Reset Threshold VCC3 Reset Threshold VCC5 Reset Threshold VCCA VCC3 or VCC5 Operating Voltage VCC3 Supply Current VCC5 Input Current VCCA Input Current Reset Pulse Width Soft Reset Pulse Width VCC Undervoltage Detect to RST RST in Correct Logic State PBR = VCC3 VCC5 = 5V VCCA = 1V RST Low with 10k Pull-Up to VCC3 SRST Low with 10k Pull-Up to VCC3 VCC5, VCC3 or VCCA Less than Reset Threshold VRT by 1% CONDITIONS
q q q q q q q q q
2
U
U
W
WW
U
W
TOP VIEW VCC3 1 VCC5 2 VCCA 3 GND 4 8 PBR 7 SRST 6 RST 5 RST
ORDER PART NUMBER LTC1536CS8 S8 PART NUMBER 1536
S8 PACKAGE 8-LEAD PLASTIC SO
TJMAX = 125C, JA = 150C/ W
MIN 2.959 4.687 0.992 1
TYP 2.985 4.725 1.000 100 10
MAX 3.008 4.762 1.007 7 200 20 5 280 200
UNITS V V V V A A nA ms s s
-5 140 50
0 200 100 13
LTC1536
ELECTRICAL CHARACTERISTICS
VCC3 = 3.3V, VCC5 = 5V, VCCA = VCC3, TA = 25C unless otherwise noted.
SYMBOL IPBR VIL VIH tPW tDB tPB VOL PARAMETER PBR Pull-Up Current PBR, RST Input Low Voltage PBR, RST Input High Voltage PBR Min Pulse Width PBR Debounce PBR Assertion Time to Reset RST Output Voltage Low Deassertion of PBR Input to SRST Output (PBR Pulse Width = 1s) PBR Held Less Than VIL ISINK = 5mA ISINK = 100A, VCC3 = 1V, VCC5 = 0V ISINK = 100A, VCC3 = 0V, VCC5 = 1V ISINK = 100A, VCC3 = 1V, VCC5 = 1V ISINK = 2.5mA ISINK = 2.5mA ISOURCE = 1A ISOURCE = 1A ISOURCE = 600A CRST = 20pF CRST = 20pF VCC5 Drops Below 4.25V or VCC3 Drops q Below 2.5V (Note 5) VCC5 Drops Below VCC3 By 300mV (Note 6)
q
CONDITIONS PBR = 0V
q q q q q q q q q q q q q q q
MIN 3 2 40
TYP 7
MAX 10 0.8
UNITS A V V ns
20 1.4 2.0 0.15 0.05 0.05 0.05 0.15 0.15 VCC3 - 1 VCC3 - 1 VCC3 - 1 25 45 150 50
35 2.8 0.4 0.4 0.4 0.4 0.4 0.4
ms s V V V V V V V V V ns ns
SRST Output Voltage Low RST Output Voltage Low VOH RST Output Voltage High (Note 3) SRST Output Voltage High (Note 3) RST Output Voltage High tPHL tPLH tFAIL1 tFAIL2 Propagation Delay RST to RST High Input to Low Output Propagation Delay RST to RST Low Input to High Output VCC5 or VCC3 0.5V Undervoltage to RST (Note 4) VCC5 < (VCC3 - 300mV) to RST (Note 4)
450 90
ns ns
The q denotes specifications which apply over the full operating temperature range. Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note 2: All voltage values are with respect to GND. Note 3: The output pins SRST and RST have weak internal pull-ups to VCC3 of 6A. However, external pull-up resistors may be used when faster rise times are required.
Note 4: Conforms to PCI Local Bus Specification Rev 2.1, Sect. 4.3.2 for tFAIL. Note 5: VCC3 or VCC5 falling at 0.1V/s, time measured from VRTX - 500mV to RST at 1.5V. Note 6: VCC5 falling from 5V to 3V in 10ns, time measured from VCC5 = (VCC3 - 300mV) to RST at 1.5V.
3
LTC1536 TYPICAL PERFORMANCE CHARACTERISTICS
VCC3 Typical Transient Duration vs Reset Comparator Overdrive
50
TYPICAL TRANSIENT DURATION (s)
TYPICAL TRANSIENT DURATION (s)
TYPICAL TRANSIENT DURATION (s)
45 40 35 30 25 20 15 10 5
RESET OCCURS ABOVE CURVE
0 0.01 0.1 1 0.001 VCC3 RESET COMPARATOR OVERDRIVE, VRT3 - VCC3 (V)
1536 G01
PIN FUNCTIONS
VCC3 (Pin 1): 3.3V Sense Input and Power Supply Pin for the IC. Bypass to ground with 0.1F ceramic capacitor. VCC5 (Pin 2): 5V Sense Input. VCCA (Pin 3): 1V Sense, High Impedance Input. If unused it can be tied to either VCC3 or VCC5. GND (Pin 4): Ground. RST (Pin 5): Reset Logic Output. Active high CMOS logic output, drives high to VCC3, buffered compliment of RST. An external pull-down on the RST pin will drive this pin high. RST (Pin 6): Reset Logic Output. Active low, open-drain logic output with weak pull-up to VCC3. Can be pulled up greater than VCC3 when interfacing to 5V logic. Asserted when one or more of the supplies are below trip thresholds and held for 200ms after all supplies become valid. Also asserted after PBR is held low for more than two seconds and for an additional 200ms after PBR is released. SRST (Pin 7): "Soft" Reset. Active low, open-drain logic output with weak pull-up to VCC3. Can be pulled up greater than VCC3 when interfacing to 5V logic. Asserted for 100s after PBR is held low for less than two seconds and released. PBR (Pin 8): Push-Button Reset. Active low logic input with weak pull-up to VCC3. Can be pulled up greater than VCC3 when interfacing to 5V logic. When asserted for less than two seconds, outputs a soft reset 100s pulse on the SRST pin. When PBR is asserted for greater than two seconds, the RST output is forced low and remains low until 200ms after PBR is released.
4
UW
VCC5 Typical Transient Duration vs Reset Comparator Overdrive
45 40 35 30 25 20 15 10 5 RESET OCCURS ABOVE CURVE
VCCA Typical Transient Duration vs Reset Comparator Overdrive
40 35 30 25 20 15 10 5 0 0.001 0.01 0.1 1 VCCA RESET COMPARATOR OVERDRIVE, VRTA - VCCA (V)
1536 G03
RESET OCCURS ABOVE CURVE
0 0.001 0.01 0.1 1 VCC5 RESET COMPARATOR OVERDRIVE, VRT5 - VCC5 (V)
1536 G01
U
U
U
LTC1536
BLOCK DIAGRAM
VCC3 7A 6A
PBR 8 TO POWER DETECT AND VCC INTERNAL VCC3 1
-
VCC5 2 TO POWER DETECT
VCCA 3
GND 4
REF
+
+
+
+
+
-
-
-
-
-
W
VCC3 7 SRST SOFT RESET PBR TIMER RESET FAST SLOW VCC3 6A 6 RST VCC3 5 RST VCC5 VCC3
+
FAST
200ms RESET GENERATOR
POWER DETECT/ GATE DRIVE
FAST
SLOW
SLOW
1536 BD
5
LTC1536
TI I G DIAGRA S
VCC Monitor Timing
VCCX VRTX tRST RST
1536 TD01
tFAIL1 Fast Undervoltage Detect
SLEW RATE 0.1V/s VRTX VCC3 OR VCC5 500mV
tFAIL1
RST
1536 TD03
APPLICATIONS INFORMATION
Operation The LTC1536 is a low power, high accuracy triple supply monitoring circuit. This reset generator has two basic functions: generation of a reset when power supplies are out of range, and generation of a reset or "soft" reset when the reset button is pushed. The LTC1536 has the added feature that when the reset supplies are grossly undervoltage there is a very short delay from undervoltage detect to assertion of RST. Supply Monitoring All three VCC inputs must be above predetermined thresholds for 200ms before the reset output is released. The LTC1536 will assert reset during power-up, power-down and brownout conditions on any one or more of the VCC inputs. On power-up, either the VCC5 or VCC3 pin can power the drive circuits for the RST pin. This ensures that RST will be low when either VCC5 or VCC3 reaches 1V. As long as any one of the VCC inputs is below its predetermined threshold, RST will stay a logic low. Once all of the VCC inputs rise above their thresholds, an internal timer is started and RST is released after 200ms. RST outputs the inverted state of what is seen on RST. RST is reasserted whenever any one of the VCC inputs drops below its predetermined threshold and remains asserted until 200ms after all of the VCC inputs are above their thresholds. On power-down, once any of the VCC inputs drops below its threshold, RST is held at a logic low. A logic low of 0.4V is guaranteed until both VCC3 and VCC5 drop below 1V. Push-Button Reset The LTC1536 provides a push-button reset input pin. The PBR input has an internal pull-up current source to VCC3. If the PBR pin is not used it can be left floating. When the PBR is pulled low for less than tPB ( 2 sec), a narrow (100s typ) soft reset pulse is generated on the SRST output pin after the button is released. The pushbutton circuitry contains an internal debounce counter
6
U
W
W
U
U
UW
Push-Button Reset Function Timing
PBR t < tPB tDB RST tSRST SRST
1536 TD02
tPB
tRST
tFAIL2 Fast Undervoltage Detect
FALL TIME 10ns, VCC3 = 3.3V 3.3V 300mV VCC5
tFAIL2
RST
1536 TD04
LTC1536
APPLICATIONS INFORMATION
which delays the output of the soft reset pulse by typically 20ms. This pin can be OR-tied to the RST pin and issue what is called a "soft" reset. The SRST thereby resets the microprocessor without interrupting the DRAM refresh cycle. In this manner DRAM information remains undisturbed. Alternatively, SRST may be monitored by the processor to initiate a software-controlled reset. When the PBR pin is held low for longer than tPB ( 2 sec), a standard reset is generated. Once the 2-second period has elapsed, a reset signal is produced by the pushbutton logic, thereby clearing the reset counter. Once the PBR pin is released, the reset counter begins counting the reset period (200ms nominal). Consequently, the reset outputs remain asserted for approximately 200ms after the button is released. Fast Undervoltage for PCI Applications The LTC1536 is designed for PCI Local Bus applications that require reset to be asserted quickly in response to one or both of the power supply rails (5V and 3.3V) going out of spec. The spec for tFAIL is met with enough margin to give the designer the ability to add follow-on logic as needed by system requirements. The VCCA pin can be used to monitor the "power good" signal and keep reset applied until both supplies are in spec and the power good signal is high. Glitch Immunity and Fast Undervoltage Detection The LTC1536 achieves its high speed characteristics while maintaining glitch immunity by using two sets of comparators. Both the VCC5 and VCC3 sense inputs each have two comparators set at different thresholds. A slow, very accurate comparator monitors the supply for precision undervoltage detection. In parallel, with a lower threshold, is a very fast comparator that detects when the supply is grossly out of specification. 3V or 5V Power Detect/Gate Drive The LTC1536 for the most part is powered internally from the VCC3 pin. The exception is at the gate drive of the output FET on the RST pin. On the input to this FET is power detect circuitry used to detect and drive the gate from either the 3.3V pin or the 5V pin, whichever pin has the highest potential. This ensures the part pulls the RST pin low as soon as either input pin is 1V.
TYPICAL APPLICATIONS N
SRST Tied to RST and OR-Tying Other Sources to RST to Generate Reset and Reset
PUSH-BUTTON 8 3.3V
LTC1536
PBR
6A SRST 7
4.7k RESET
6A RST 6 VCC3 RST 5 RESET OTHER OPEN DRAIN RESET SOURCES OR-TIED TO RESET
U
W
U
U
U
Using VCCA Tied to DC/DC Feedback Divider
2.9V LTC1435 VOSENSE 6 35.7k 1% 3.3V 2.8k 1% ADJUSTABLE RESET TRIP THRESHOLD 2.74V 22.1k 1% 5V LTC1536 1 2 3 4 VCC3 VCC5 VCCA GND PBR SRST RST RST 8 7 6 5 SYSTEM RESET
1536 TA06
1536 TA05
7
LTC1536
TYPICAL APPLICATIONS N
Dual Supply Monitor (3.3V and 5V, VCCA Input Monitoring "Power Good")
LTC1536 3.3V 5V PWR GOOD 1 2 3 4 VCC3 VCC5 VCCA GND PBR SRST RST RST 8 7 6 5
1536 TA04
1536 TA03
PACKAGE DESCRIPTION
0.007 (0.18) 0.021 0.004 (0.53 0.01)
0 - 6 TYP 0.192 0.004 (4.88 0.10) 0.025 (0.65) TYP 1 23 4
MSOP08 0595
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254)
0.016 - 0.050 0.406 - 1.270
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
RELATED PARTS
PART NUMBER LTC690 LTC694-3.3 LTC699 LTC1232 LTC1326 DESCRIPTION 5V Supply Monitor, Watchdog Timer and Battery Backup 3.3V Supply Monitor, Watchdog Timer and Battery Backup 5V Supply Monitor and Watchdog Timer 5V Supply Monitor, Watchdog Timer and Push-Button Reset Micropower Precision Triple Supply Monitor COMMENTS 4.65V Threshold 2.9V Threshold 4.65V Threshold 4.37V/4.62V Threshold 4.725V, 3.118V, 1V Thresholds (0.75%)
1536I LT/TP 0897 4K * PRINTED IN USA
8
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417 q (408) 432-1900 FAX: (408) 434-0507q TELEX: 499-3977 q www.linear-tech.com
U
U
Triple Supply Monitor (3.3V, 5V and Adjustable)
LTC1536 3.3V ADJUSTABLE SUPPLY OR DC/DC FEEDBACK DIVIDER R1 5V 1 2 3 R2 4 VCC3 VCC5 VCCA GND PBR SRST RST RST 8 7 6 5 SYSTEM RESET
SYSTEM RESET
Dimensions in inches (millimeters) unless otherwise noted. MS8 Package 8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
0.040 0.006 (1.02 0.15) 0.006 0.004 (0.15 0.10) 0.118 0.004* (3.00 0.10) 8 76 5
0.012 (0.30)
0.118 0.004** (3.00 0.10)
S8 Package 8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.053 - 0.069 (1.346 - 1.752) 0- 8 TYP 0.228 - 0.244 (5.791 - 6.197) 0.150 - 0.157** (3.810 - 3.988) 0.004 - 0.010 (0.101 - 0.254) 8 0.189 - 0.197* (4.801 - 5.004) 7 6 5
0.014 - 0.019 (0.355 - 0.483)
0.050 (1.270) BSC
SO8 0695
1
2
3
4
(c) LINEAR TECHNOLOGY CORPORATION 1997

▲Up To Search▲

Price & Availability of 1536I

	To Download 1536I Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .