LTC4260 Linear Technology, LTC4260 Datasheet
LTC4260
Available stocks
Related parts for LTC4260
LTC4260 Summary of contents
Page 1
... ADC allow monitoring of board current, voltage and fault status. The device features adjustable analog foldback current limit with latch off or automatic restart after the LTC4260 remains in current limit beyond an adjustable time-out delay. The controller has additional features to interrupt the host ...
Page 2
... (Notes 1, 2) ALERT, SDAO ........................................... –0.3V to 6.5V Supply Voltage (INTV Operating Temperature Range DD LTC4260C ............................................... 0°C to 70°C LTC4260I ............................................. –40°C to 85°C + 0.3V Storage Temperature Range CC GN, SW Packages ............................. – 65°C to 150°C UH Package ...................................... – 65°C to 125°C Lead Temperature (Soldering, 10 sec) GN, SW Packages Only..................................... 300°C ...
Page 3
... FB = 3.5V V Rising BD_PRST BD_PRST = 0V V Rising GPIO I = 2mA GPIO V = 80V GPIO V = 1.28V ADIN V = 2.56V ADIN V Rising TIMER V Falling TIMER TIMER V = 1.3V TIMER LTC4260 MIN TYP MAX UNITS ● 3.4 3.8 4.2 V ● ● 50 100 150 ms ● ● 4 ● –14 –18 – ...
Page 4
... LTC4260 ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL PARAMETER AC Parameters t Input High (ON) to GATE High PLH(GATE) Propagation Delay t Input High (OV, BD_PRST), Input Low PHL(GATE) (ON, UV) to GATE Low Propagation Delay t (V – SENSE) High to GATE Low PHL(SENSE) DD ADC Resolution (No Missing Codes) ...
Page 5
... LOAD 4260 G18 ON, BD_PRST Low-High Threshold vs Temperature 1.245 1.240 1.235 1.230 1.225 1.220 –50 – 100 TEMPERATURE (°C) 4260 G04 LTC4260 = 48V unless otherwise noted Low-High Threshold vs Temperature 3.54 3.52 3.50 3.48 3.46 –50 – 100 TEMPERATURE (°C) 4260 G02 ON, BD_PRST Hysteresis vs Temperature 0 ...
Page 6
... LTC4260 W U TYPICAL PERFOR A CE CHARACTERISTICS TIMER Pull-Up Current vs Temperature –110 –105 –100 –95 –90 –50 – 100 TEMPERATURE (°C) 4260 G06 I Pull Up vs Temperature GATE –25 –20 –15 –10 –50 – 100 TEMPERATURE (°C) 4260 G09 ...
Page 7
... During turn-off there is a 1mA pull-down current. During a short circuit or under- voltage lockout (V current source between GATE and SOURCE is activated. GND: Device Ground. LTC4260 = 48V unless otherwise noted. DD ADC DNL vs Code (ADIN Pin) 0.50 0.25 0 – ...
Page 8
... LTC4260 CTIO S GPIO: General Purpose Input/Output. Open-drain logic output and logic input. Defaults to pull low to indicate power is bad. Configure according to Table 3. NC: No Connect. Unconnected pins. These pins provide extra distance between high and low voltage pins. ON: On Control Input. A rising edge turns on the external N-channel FET and a falling edge turns it off ...
Page 9
... RESET LOGIC BOARD PRESENT + 0.2V TM1 – ONS + TM2 – 1.235V V UVLO DD 8 A/D CONVERTER ADDR ADR0 ADR1 ADR2 LTC4260 V SENSE DDK CHARGE – PUMP 20mV TO CS AND 50mV SOURCE GATE + – + DRIVER FET – 1.8V INTV CC 100µA TIMER 2µ ...
Page 10
... U OPERATIO The Functional Diagram displays the main functional areas of this device. The LTC4260 is designed to turn a board’s supply voltage on and off in a controlled manner, allowing the board to be safely inserted or removed from a live backplane. During normal operation, the charge pump and gate driver turn on the external N-channel pass FET’ ...
Page 11
... U U APPLICATIO S I FOR ATIO The typical LTC4260 application high availability system that uses a positive voltage supply to distribute power to individual cards. The device measures card voltages and currents and records past and present fault conditions. The system queries each LTC4260 over the I periodically and reads the stored information ...
Page 12
... W U Overcurrent Fault GATE The LTC4260 features an adjustable current limit with foldback that protects against short circuits or excessive load current. To protect against excessive power dissipa- tion in the switch during active current limit, the available current is reduced as a function of the output voltage V sensed by the FB pin ...
Page 13
... If the system shuts down due to a fault, it may be desirable to restart the system simply by removing and reinserting a load card. In cases where the LTC4260 and the switch reside on a backplane or midplane and the load resides on a plug-in card, the BD_PRST pin can be used to detect when the plug-in card is removed (see Figure 4) ...
Page 14
... Address, the LTC4260 responds with its address on the SDA line and releases ALERT as shown in Figure 11. If there is a collision between two LTC4260s responding with their addresses simultaneously, then the device with the lower address wins arbitration and responds first. The ALERT line will also be released if the device is addressed by the bus master ...
Page 15
... W U Supply Transient Protection The LTC4260 is 100% tested and guaranteed to be safe from damage with supply voltages up to 100V. However, spikes above 100V may damage the part. During a short- circuit condition, the large change in currents flowing through the power supply traces can cause inductive voltage spikes which could exceed 100V ...
Page 16
... 0.81ms OV(TH) GND = UV(TH) = 3.5V FB pin, as close as possible between INTV CC SENSE RESISTOR R LOAD S SENSE LTC4260 GND INTV I LOAD Figure 5. Recommended Layout for R1, R2, R3, R8 C3, Z1 and and GND ...
Page 17
... LTC4260, regardless of their individual address settings. The mass write can be masked by setting register bit A4 to zero. Address (0001 100)b is the SMBus Alert Response Address. If the LTC4260 is pulling low on the ALERT pin, it will acknowledge this address using the SMBus Alert Response Protocol. ...
Page 18
... the special Alert Response Address (0001 100)b with the R/W bit set to one. Any LTC4260 that is pulling its ALERT pin low will acknowledge and begin sending back its individual slave address. An arbitration scheme ensures that the LTC4260 with the lowest address will have priority; all others will abort their response ...
Page 19
... Figure 8. LTC4260 Serial Bus SDA Write Word Protocol ADDRESS W A COMMAND A S ADDRESS 1 0 a4: b2: a4:a0 Figure 9. LTC4260 Serial Bus SDA Read Byte Protocol W A COMMAND A S ADDRESS b2: a4: ALERT DEVICE S ...
Page 20
... LTC4260 U U APPLICATIO S I FOR ATIO 2 Table 1. LTC4260 I C Device Addressing HEX DEVICE DESCRIPTION ADDRESS h 6 Mass Write BE 1 Alert Response ...
Page 21
... U U APPLICATIO S I FOR ATIO Table 2. LTC4260 Register Addresses and Contents REGISTER REGISTER ADDRESS* NAME READ/WRITE 00h CONTROL (A) 01h ALERT (B) 02h STATUS (C) 03h FAULT (D) 04h SENSE (E) 05h SOURCE (F) 06h, 07h ADIN (G) *Register address MSBs b7-b3 are ignored. **Writable if bit A5 set. Table 3. CONTROL Register A (00h)—Read/Write ...
Page 22
... LTC4260 U U APPLICATIO S I FOR ATIO Table 4. ALERT Register B (01h)—Read/Write BIT NAME B7 Reserved B6 GPIO Output B5 FET Short Alert B4 BD_PRST State Change Alert B3 Power Bad Alert B2 Overcurrent Alert B1 Undervoltage Alert B0 Overvoltage Alert Table 5. STATUS Register C (02h)—Read Only BIT NAME C7 FET On ...
Page 23
... Current Sense Voltage Data. 8-Bit Data with 300µV LSB and 76.8mV Full Scale DD OPERATION SOURCE Pin Voltage Data. 8-Bit Data with 400mV LSB and 102.4V Full Scale OPERATION ADIN Pin Voltage Data. 8-Bit Data with 10mV LSB and 2.56V Full Scale LTC4260 4260f 23 ...
Page 24
... F12 Q1 S FDB3632 R5 C1 10Ω R6 6.8nF 100k 43.7k SENSE GATE SOURCE ADIN 3.57k 20 LTC4260GN GPIO 1% 14 BD_PRST 12 TIMER ADR0 ADR1 ADR2 GND 68nF Q2 CMPTA42 OPTIONAL 5V C2 0.1µF 4260 F13 OUTPUT C L 330µF 100V – ...
Page 25
... BSC .015 ± .004 × 45° .0532 – .0688 (0.38 ± 0.10) (1.35 – 1.75) 0° – 8° TYP .008 – .012 (0.203 – 0.305) TYP LTC4260 .337 – .344* (8.560 – 8.738) .033 (0.838 ...
Page 26
... LTC4260 PACKAGE DESCRIPTIO .050 BSC .030 ±.005 TYP N .420 MIN RECOMMENDED SOLDER PAD LAYOUT .291 – .299 (7.391 – 7.595) NOTE 4 .010 – .029 × 45° (0.254 – 0.737) .005 (0.127) RAD MIN .009 – .013 NOTE 3 (0.229 – 0.330) .016 – ...
Page 27
... U UH Package 32-Lead Plastic QFN (5mm × 5mm) (Reference LTC DWG # 05-08-1693) 0.70 ±0.05 PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 0.75 ± 0.05 0.00 – 0.05 3.45 ± 0.10 (4-SIDES) 0.200 REF LTC4260 BOTTOM VIEW—EXPOSED PAD 0.23 TYP R = 0.115 (4 SIDES) TYP 31 32 0.40 ± 0. (UH) QFN 0603 0.25 ± 0.05 0.50 BSC ...
Page 28
... FDB3632 10Ω 100k 6.8nF UV V SENSE GATE SOURCE GPIO SDAI LTC4260 BD_PRST SDA0 ADIN SCL TIMER ALERT INTV ADR0 ADR1 ADR2 GND CC NC 0.1µF COMMENTS Active Current Limiting, Supplies from 9V to 80V Withstands ±200V, Monitors Under-/Overvoltage and External Fuses ...