Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsPMICsPMIC - system monitor Dual voltage detector MSOP 10

LTC2900

2900f

Programmable Quad Supply

Monitor with Adjustable Reset Timer

■

Simultaneously Monitors Four Supplies

■

16 User Selectable Combinations of 5V, 3.3V, 3V,

2.5V, 1.8V, 1.5V and/or ±Adjustable Voltage

Thresholds

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Guaranteed Threshold Accuracy: ±1.5% of

Monitored Voltage Over Temperature

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Low Supply Current: 43µA Typ

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Adjustable Reset Time

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Small MSOP and 3mm × 3mm DFN Packages

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Manual Reset Pin

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Open-Drain RST Output (LTC2900-1)

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Push-Pull RST Output (LTC2900-2)

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Power Supply Glitch Immunity

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Guaranteed RST for V

≥ 1V

The LTC

2900 is a programmable supply monitor for

systems with up to four supply voltages. One of 16 preset

or adjustable voltage monitor combinations can be se-

lected using an external resistor divider connected to the

program pin. The preset voltage thresholds are accurate

to ±1.5% over temperature.

The reset delay time is adjustable using an external

capacitor and the manual reset input may be used with a

momentary switch to issue reset pulses with programmed

duration. Tight voltage threshold accuracy and glitch

immunity ensure reliable reset operation without false

triggering. The RST output is guaranteed to be in the

correct state for V

down to 1V. The LTC2900-1 features

an open-drain RST output, while the LTC2900-2 has a

push-pull RST output.

The 43µA supply current makes the LTC2900 ideal for

power conscious systems and it may be configured to

monitor less than four inputs. The parts are available in

the 10-lead MSOP

and the 10-lead 3mm × 3mm DFN

packages.

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Desktop and Notebook Computers

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Multivoltage Systems

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Telecom Equipment

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Portable Battery-Powered Equipment

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Network Servers

, LTC and LT are registered trademarks of Linear Technology Corporation.

REF

GND

59k

40.2k

1.8V

47nF

PUSH-BUTTON

RESET

0.1µF

V3 V4

LTC2900-2

CRT

PBR

RST

= 216ms

2900 TA01

SYSTEM

LOGIC

DC/DC

CONVERTER

2.5V

3.3V

Quad Supply Monitor (5V, 3.3V, 2.5V, 1.8V)

DESCRIPTIO

FEATURES

APPLICATIO S

TYPICAL APPLICATIO

Summary of content (16 pages)

PAGE 1
LTC2900 Programmable Quad Supply Monitor with Adjustable Reset Timer U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO Simultaneously Monitors Four Supplies 16 User Selectable Combinations of 5V, 3.3V, 3V, 2.5V, 1.8V, 1.5V and/or ±Adjustable Voltage Thresholds Guaranteed Threshold Accuracy: ±1.
PAGE 2
LTC2900 W W W AXI U U ABSOLUTE RATI GS (Notes 1, 2, 3) V1, V2, V3, V4, VPG, PBR ............................. – 0.3V to 7V RST (LTC2900-1)........................................ – 0.3V to 7V RST (LTC2900-2).......................... – 0.3V to (V2 + 0.3V) CRT ............................................. – 0.3V to (VCC + 0.3V) VREF ............................................. – 0.3V to (VCC + 0.3V) Reference Load Current (IVREF) ............................ ±1mA V4 Input Current (– ADJ Mode) .....
PAGE 3
LTC2900 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, unless otherwise noted. (Note 3) SYMBOL PARAMETER CONDITIONS IV2 V2 Input Current V2 = 3.3V ● 0.8 2 µA IV3 V3 Input Current V3 = 2.5V V3 = 0.55V (ADJ Mode) ● ● 0.52 –15 1.2 15 µA nA V4 = 1.8V V4 = 0.55V (ADJ Mode) V4 = –0.05V (–ADJ Mode) ● ● ● 0.34 –15 –15 0.
PAGE 4
LTC2900 WU W TI I G DIAGRA Monitor Timing VX VRTX tPBD tRST tUV tRST 1.5V RST 2900 TD PBR tPBW U W TYPICAL PERFOR A CE CHARACTERISTICS 5V Threshold Voltage vs Temperature 3.3V Threshold Voltage vs Temperature THESHOLD VOLTAGE, VRT50 (V) 4.725 4.700 4.675 4.650 4.625 3.135 2.850 3.125 2.840 THRESHOLD VOLTAGE, VRT30 (V) THRESHOLD VOLTAGE, VRT33 (V) 4.750 3V Threshold Voltage vs Temperature 3.115 3.105 3.095 3.085 3.075 3.065 3.055 3.
PAGE 5
LTC2900 U W TYPICAL PERFOR A CE CHARACTERISTICS ADJ Threshold Voltage vs Temperature – ADJ Threshold Voltage vs Temperature 0.504 0.502 0.500 0.498 0.496 0.494 0.492 – 60 –40 – 20 0 20 40 60 TEMPERATURE (°C) 80 1.228 0.012 1.222 0.006 1.216 VREF (V) 0.506 THRESHOLD VOLTAGE, VRTAN (V) 0 1.204 –0.012 1.198 –0.018 – 60 –40 – 20 0 20 40 60 TEMPERATURE (°C) 100 2900 G07 IV1 vs Temperature 1.192 – 60 –40 – 20 0 20 40 60 TEMPERATURE (°C) 100 IV2 vs Temperature V1 = 5V 1.4 V2 = 3.3V V3 = 2.
PAGE 6
LTC2900 U W TYPICAL PERFOR A CE CHARACTERISTICS RST Output Voltage vs V1, VPG = 0V Reset Time-Out Period vs Temperature 8.9 5 3 2 1 0 0 10 CRT = 1500pF 8.4 (SILVER MICA) RESET TIME-OUT PERIOD, tRST (sec) RESET TIME-OUT PERIOD, tRST (ms) V1 = V2 = V3 = V4 10k PULL-UP FROM RST TO V1 TA = 25°C 4 RST OUTPUT VOLTAGE (V) Reset Time-Out Period vs Capacitance 7.9 7.4 6.4 5.9 5.
PAGE 7
LTC2900 U U U PI FU CTIO S V3 (Pin 1): Voltage Input 3. Select from 2.5V, 1.8V, 1.5V or ADJ. See Table 1 for details. V1 (Pin 2): Voltage Input 1. Select from 5V or 3.3V. See Table 1 for details. The greater of (V1, V2) is also VCC for the device. Bypass this pin to ground with a 0.1µF (or greater) capacitor. CRT (Pin 3): Reset Delay Time Programming Pin. Attach an external capacitor (CRT) to GND to set a reset delay time of 4.6ms/nF. Leaving the pin open generates a minimum delay of approximately 50µs.
PAGE 8
LTC2900 W BLOCK DIAGRA V1 – POWER DETECT + VCC V2 – V1 2 V2 10 + RESISTIVE DIVIDER MATRIX V3 1 – V4 9 + LTC2900-1 V2 6µA GND 6 RST – 4 ADJUSTABLE RESET PULSE GENERATOR + VPG 2µA A/D 7 BUFFER VREF 8 VCC 1.
PAGE 9
LTC2900 U W U U APPLICATIO S I FOR ATIO Table 1. Voltage Threshold Programming Power-Up The greater of V1, V2 is the internal supply voltage (VCC). On power-up, VCC will power the drive circuits for the RST pin. This ensures that the RST output will be low as soon as V1 or V2 reaches 1V. The RST output will remain low until the part is programmed. After programming, if any one of the VX inputs is below its programmed threshold, RST will be a logic low.
PAGE 10
LTC2900 U W U U APPLICATIO S I FOR ATIO VTRIP 8 LTC2900 R3 1% R4 1% + V3 OR V4 VREF 9 V4 R3 1% R4 1% – + – LTC2900 – + VTRIP 0.5V 2900 F06 2900 F05 Figure 5. Setting the Positive Adjustable Trip Point sensed and ground, is connected to the high impedance noninverting inputs (V3, V4). The trip voltage is calculated from:  R3  VTRIP = 0.5V 1 +   R4  In the negative adjustable mode, the noninverting input on the V4 comparator is connected to ground (Figure 6).
PAGE 11
LTC2900 U W U U APPLICATIO S I FOR ATIO Although all four supply monitor comparators have builtin glitch immunity, bypass capacitors on V1 and V2 are recommended because the greater of V1 or V2 is also the VCC for the device. Filter capacitors on the V3 and V4 inputs are allowed. Power-Down On power-down, once any of the VX inputs drop below their threshold, RST is held at a logic low. A logic low of 0.4V is guaranteed until both V1 and V2 drop below 1V.
PAGE 12
LTC2900 U W U U APPLICATIO S I FOR ATIO Ensuring Reset Valid for VCC Down to 0V (LTC2900-2) Some applications require the reset output (RST) to be valid with VCC down to 0V. The LTC2900-2 is designed to handle this requirement with the addition of an external resistor from RST to ground. The resistor will provide a path for stray charge and/or leakage currents, preventing the RST output from floating to undetermined voltages when connected to high impedance (such as CMOS logic inputs).
PAGE 13
LTC2900 U TYPICAL APPLICATIO S 5V, 3.3V, 12V, –5.2V Monitor with Manual Reset and LED Indication on RST 12V R5 VTRIP = 11.25V 2.15M 1% R6 100k 1% 1 V2 10 3.3V 9 V4 V1 LTC2900-1 8 VREF CRT 4 7 RST VPG 6 5 PBR GND 2 5V RL1 1k SYSTEM RESET V3 CRT LED 10k* R3 487k 1% R4 121k 1% R1 93.1k 1% R2 9.53k 1% 3 MANUAL RESET BUTTON (NORMALLY OPEN) *OPTIONAL RESISTOR RECOMMENDED TO EXTEND ESD TOLERANCE –5.2V VTRIP = –4.87V 2900 TA05 Low Voltage Quad Supply Monitor 3.3V, 2.5V, 1V (ADJ), 0.9V (ADJ) R5 86.
PAGE 14
LTC2900 U PACKAGE DESCRIPTIO DD Package 10-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1699) 0.675 ±0.05 3.50 ±0.05 1.65 ±0.05 2.15 ±0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 2.38 ±0.05 (2 SIDES) R = 0.115 TYP RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 3.00 ±0.10 (4 SIDES) 0.38 ± 0.10 6 10 5 1 1.65 ± 0.10 (2 SIDES) PIN 1 TOP MARK (SEE NOTE 5) 0.200 REF (DD10) DFN 0403 0.75 ±0.05 0.00 – 0.05 0.25 ± 0.05 0.50 BSC 2.38 ±0.10 (2 SIDES) BOTTOM VIEW—EXPOSED PAD NOTE: 1.
PAGE 15
LTC2900 U PACKAGE DESCRIPTIO MS Package 10-Lead Plastic MSOP (Reference LTC DWG # 05-08-1661) 0.889 ± 0.127 (.035 ± .005) 5.23 (.206) MIN 3.2 – 3.45 (.126 – .136) 3.00 ± 0.102 (.118 ± .004) (NOTE 3) 0.50 0.305 ± 0.038 (.0197) (.0120 ± .0015) BSC TYP RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) 0.497 ± 0.076 (.0196 ± .003) REF 10 9 8 7 6 3.00 ± 0.102 (.118 ± .004) NOTE 4 4.90 ± 0.15 (1.93 ± .006) DETAIL “A” 0° – 6° TYP GAUGE PLANE 1 2 3 4 5 0.53 ± 0.01 (.021 ± .006) DETAIL “A” 1.10 (.043) MAX 0.
PAGE 16
LTC2900 U TYPICAL APPLICATIO Monitor Eight Supplies Using Supervisory Cascade 12V (ADJ), 5V, 3.3V, 3V, 2.5V, 1.8V, 1V (ADJ), – 5V (– ADJ) R5A 86.6k 1% MASTER RESET R3B 464k 1% –5V 2.5V 1V R3A 2150k 1% 3V 1 12V 5V V3 V2 10 9 V4 V1 LTC2900-2 8 VREF CRT 4 7 RST VPG 5 6 PBR GND 1 1.8V 2 R6A 100k 1% CRTA 20k V2 R4B 121k 1% 10 9 V4 V1 LTC2900-2 8 VREF CRT 4 7 RST VPG 6 5 PBR GND 2 3.3V 3 3 R4A 100k 1% V3 R1A 40.2k 1% CRTB R2A 59k 1% R1B 22.1k 1% R2B 78.