Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsPMICsPMIC - power supply controllers/monitors 6 µA DFN 8 (3x2)

LTC2950-1/LTC2950-2

295012fd

2V/DIV

10ms/DIV

2950 TA01b

Pushbutton On/Off

Controller

The LTC

2950 is a micropower, wide input voltage range,

pushbutton ON/OFF controller. The part contains a pushbut-

ton input with independently programmable ON and OFF

debounce times that control the toggling of an open drain

enable output. The part also contains a simple micropro-

cessor interface to allow for proper system housekeeping

prior to power down. Under system fault conditions, an

internal KILL timer ensures proper power down.

The LTC2950 operates over a wide 2.7V to 26.4V input

voltage range to accommodate a wide variety of input

power supplies. Very low quiescent current (6µA typical)

makes the LTC2950 ideally suited for battery powered

applications. Two versions of the part are available to ac-

commodate either positive or negative enable polarities.

The parts are available in either 8-lead 3mm × 2mm DFN

or ThinSOT packages.

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and

ThinSOT and PowerPath are trademarks of Linear Technology Corporation. All other trademarks

are the property of their respective owners.

Portable Instrumentation Meters

Blade Servers

Portable Customer Service PDA

Desktop and Notebook Computers

Adjustable Pushbutton On/Off Timers

Low Supply Current: 6µA

Wide Operating Voltage Range: 2.7V to 26.4V

EN Output (LTC2950-1) Allows DC/DC Converter

Control

EN Output (LTC2950-2) Allows Circuit Breaker

Control

Simple Interface Allows Graceful µP Shut Down

High Input Voltage PB Pin with Internal Pull Up

Resistor

±10kV ESD HBM on PB Input

Accurate 0.6V Threshold on KILL Comparator Input

8-Pin 3mm × 2mm DFN and ThinSOT™ Packages

SHDN**

OUT

INT

KILL

INT

KILL

LTC2950-1

ONT OFFT

DC/DC

BUCK

µP/µC

2.7V TO 26.4V

*OPTIONAL

**SHDN INTERNALLY PULLED UP BY DC/DC

10k

2950 TA01

ONT

0.033µF

OFFT

0.033µF

GND

Typical applicaTion

Turn On Debounce

DescripTion

FeaTures

applicaTions

Summary of content (18 pages)

PAGE 1
LTC2950-1/LTC2950-2 Pushbutton On/Off Controller Features n n n n n n n n n n Description Adjustable Pushbutton On/Off Timers Low Supply Current: 6µA Wide Operating Voltage Range: 2.7V to 26.4V EN Output (LTC2950-1) Allows DC/DC Converter Control EN Output (LTC2950-2) Allows Circuit Breaker Control Simple Interface Allows Graceful µP Shut Down High Input Voltage PB Pin with Internal Pull Up Resistor ±10kV ESD HBM on PB Input Accurate 0.
PAGE 2
LTC2950-1/LTC2950-2 Absolute Maximum Ratings (Note 1) Supply Voltage (VIN)................................... –0.3V to 33V Input Voltages PB.............................................................. –6V to 33V ONT....................................................... –0.3V to 2.7V OFFT...................................................... –0.3V to 2.7V KILL.......................................................... –0.3V to 7V Output Voltages INT.........................................................
PAGE 3
LTC2950-1/LTC2950-2 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 2.7V to 26.4V, unless otherwise noted. (Note 2) SYMBOL PARAMETER CONDITIONS VIN Supply Voltage Range Steady State Operation MIN l IIN VIN Supply Current System Power On, VIN = 2.7V to 24V l VUVL VIN Undervoltage Lockout VIN Falling l VUVL(HYST) VIN Undervoltage Lockout Hysteresis TYP 2.7 MAX UNITS 26.
PAGE 4
LTC2950-1/LTC2950-2 Typical Performance Characteristics Supply Current vs Temperature 10 10 8 VIN = 2.7V 4 2 6 4 2 0 –50 –25 0 25 50 TEMPERATURE (°C) 75 0 100 0 5 10 15 20 25 ONT Pull-Down Current vs Temperature 50 VIN = 26.4V –3.0 VIN = 2.7V –2.8 100 10 OFFT EXTERNAL CAPACITOR (nF) –25 0 25 50 TEMPERATURE (°C) 75 0 100 5 0 10 15 VIN (V) 20 25 PB Current vs PB Voltage –250 TA = 25°C VIN = 3.3V –200 –3.2 VIN = 26.4V –3.0 VIN = 2.7V –2.8 –2.
PAGE 5
LTC2950-1/LTC2950-2 Typical Performance Characteristics PB Voltage vs External PB Resistance to Ground 300 EN/EN VOL vs Current Load 500 VIN = 3.3V 400 200 EN/EN VOLTAGE (mV) PB VOLTAGE (mV) 250 TA = 100°C 150 TA = 25°C TA = –45°C 100 300 200 100 50 0 TA = 25°C VIN = 3.3V 0 0 5 10 15 20 EXTERNAL PB RESISTANCE TO GROUND (kΩ) 0 2 6 8 4 EN/EN CURRENT LOAD (mA) 2950 G10 2950 G11 EN (LTC2950-1) Voltage vs VIN 1.
PAGE 6
LTC2950-1/LTC2950-2 Pin Functions (TSOT-23/DFN) VIN (Pin 1/Pin 4): Power Supply Input: 2.7V to 26.4V. PB (Pin 2/Pin 3): Pushbutton Input. Connecting PB to ground through a momentary switch provides on/off control via the EN/EN pin. An internal 100k pull-up resistor connects to an internal 1.9V bias voltage. The rugged PB input can be pulled up to 26.4V externally without consuming extra current. ONT (Pin 3/Pin 2): Additional Adjustable Turn On Time Input.
PAGE 7
LTC2950-1/LTC2950-2 Block Diagram EN/EN VIN 2.7V TO 26.4V REGULATOR 2.4V 2.4V PB KILL OSCILLATOR 100k LOGIC 10µS FILTER DEBOUNCE 0.6V 0.
PAGE 8
LTC2950-1/LTC2950-2 TIMING DiagramS PB PB & KILL IGNORED tDB, ON tONT tKILL, ON BLANK 16 CYCLES EN (LTC2950-1) EN (LTC2950-2) 2950 TD02 Power On Timing PB tDB, OFF PB IGNORED tOFFT OFFT 16 CYCLES INT tKILL, OFF DELAY EN (LTC2950-1) EN (LTC2950-2) 2950 TD03 Power Off Timing, KILL > 0.
PAGE 9
LTC2950-1/LTC2950-2 Applications Information Description The LTC2950 is a low power (6µA), wide input voltage range (2.7V to 26.4V), pushbutton on/off controller that can interface to a µP and a power supply. The turn-on and turn-off debounce times are extendable using optional external capacitors. A simple interface (INT output, KILL input) allows a system to power on and power off in a controlled manner. Turn On When power is first applied to the LTC2950, the part initializes the output pins.
PAGE 10
LTC2950-1/LTC2950-2 Applications Information t1 t2 PB t3 t4 t5 t6 PB & KILL IGNORED tDB, ON PB IGNORED tKILL, ON BLANK tONT t7 < tKILL, OFF DELAY tDB, OFF ONT tOFFT OFFT INT
PAGE 11
LTC2950-1/LTC2950-2 Applications Information Aborted Power On Sequence The power on sequence is aborted when the KILL remains low after the end of the 512ms blanking time. Figure 2 is a simplified version of an aborted power on sequence. At time tABORT, since KILL is still low, EN pulls low (thus turning off the DC/DC converter). Figure 4 shows the µP turning power off. After a low on KILL releases enable, the internal 256ms timer ignores the PB pin. This is shown as tEN/EN, LOCKOUT in Figure 4.
PAGE 12
LTC2950-1/LTC2950-2 Applications Information The following equations describe the turn on and turn off times. CONT and COFFT are the external programming capacitors: tBD,ON + tONT = 32ms + 1ms + (6.7x106) • CONT tBD,OFF + tOFFT = 32ms + 1ms + (6.7x106) • COFFT High Voltage Pins The VIN and PB pins can operate at voltages up to 26.4V. PB can, additionally, operate below ground (–6V) without latching up the device. PB has an ESD HBM rating of ±10kV.
PAGE 13
LTC2950-1/LTC2950-2 Typical Applications PB Pin in a Noisy Environment below 0.6V, then an appropriate bypass capacitor should be connected to the KILL pin. The rugged PB pin is designed to operate in noisy environments. Transients below ground (>–6V) and above VIN (<30V) will not damage the rugged PB pin. Additionally, the PB pin can withstand ESD HBM strikes up to ±10kV. PowerPath™ Switching The EN open drain output of the LTC2950-2 is designed to switch on/off an external power PFET.
PAGE 14
LTC2950-1/LTC2950-2 Typical Applications the PB board trace, however, will affect the open circuit voltage on the PB pin. If the leakage is too large (>2µA), the PB voltage may fall close to the threshold window. To mitigate the effect of the board leakage, a 10k resistor to VIN is recommended (see Figure 9). VIN Reverse Battery Protection To protect the LTC2950 from a reverse battery connection, place a 1k resistor in series with the VIN pin (see Figure 10). VIN LTC2950-1/ LTC2950-2 2.
PAGE 15
LTC2950-1/LTC2950-2 Package Description DDB Package 8-Lead Plastic DFN (3mm × 2mm) (Reference LTC DWG # 05-08-1702 Rev B) 0.61 ±0.05 (2 SIDES) 3.00 ±0.10 (2 SIDES) 0.70 ±0.05 2.55 ±0.05 1.15 ±0.05 PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 2.20 ±0.05 (2 SIDES) PIN 1 BAR TOP MARK (SEE NOTE 6) 0.200 REF RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS R = 0.115 TYP 5 R = 0.05 TYP 0.40 ± 0.10 8 2.00 ±0.10 (2 SIDES) 0.56 ± 0.05 (2 SIDES) 0.75 ±0.05 0 – 0.05 4 0.25 ± 0.05 1 PIN 1 R = 0.20 OR 0.
PAGE 16
LTC2950-1/LTC2950-2 Package Description TS8 Package 8-Lead Plastic TSOT-23 (Reference LTC DWG # 05-08-1637 Rev A) 0.40 MAX 2.90 BSC (NOTE 4) 0.65 REF 1.22 REF 1.4 MIN 3.85 MAX 2.62 REF 2.80 BSC 1.50 – 1.75 (NOTE 4) PIN ONE ID RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR 0.22 – 0.36 8 PLCS (NOTE 3) 0.65 BSC 0.80 – 0.90 0.20 BSC 0.01 – 0.10 1.00 MAX DATUM ‘A’ 0.30 – 0.50 REF 0.09 – 0.20 (NOTE 3) 1.95 BSC TS8 TSOT-23 0710 REV A NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2.
PAGE 17
LTC2950-1/LTC2950-2 Revision History (Revision history begins at Rev D) REV DATE DESCRIPTION PAGE NUMBER D 02/11 Revised Typical Application. 1 Revised Absolute Maximum Ratings and Pin Configuration. 2 Updated Electrical Characteristics 3 Revised EN and EN pin descriptions in Pin Functions. 6 Updated Block Diagram 7 Revised Figures 5 and 6. 12 Updated Related Parts. 18 295012fd Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
PAGE 18
LTC2950-1/LTC2950-2 Typical Application 9V BATTERY VIN + R5 910k R8 1k VOUT LT1761-1.8 SHDN 1.8V VIN C4 0.1µF R1 10k EN LTC2950-1 INT INT PB KILL KILL GND ONT OFFT CONT* 0.033µF COFFT* 0.033µF *OPTIONAL µP 2950 F10 Figure 10.