LTC4419IMSE

Part: LTC4419IDD#TRPBF — Analog Devices (Linear Technology)

Type: Dual Input PowerPath Prioritizer

Description: 1.8–18 V dual input micropower PowerPath prioritizer with internal dual 2 Ω, 0.5 A switches, 3.6 μA operating current, and a ±1.5% accurate adjustable switchover threshold.

Operating Conditions:

• Supply voltage (V1, V2): 1.8–18 V
• Operating temperature: -40 to 85 °C (LTC4419I grade)
• ADJ falling threshold: 1.047 V typ; V1 valid if V1 ≥ 1.55 V and ADJ ≥ 1.097 V for 64 ms

Absolute Maximum Ratings:

• Max supply voltage (V1, V2): 24 V (-15 V to 24 V); OUT: -0.3 V to 24 V
• OUT – V1 / OUT – V2: -24 V to 39 V
• ADJ, CMP1, CMP2, CMPOUT1, CMPOUT2, V2ON: -0.3 V to 24 V
• Max junction temperature: 125 °C
• Storage temperature: -65 to 150 °C
• Lead temperature (soldering, 10 s, MSOP): 300 °C

Key Specs:

• Switch resistance: 2 Ω typ (1–5 Ω), V1 = V2 = 5 V, IOUT = -100 mA
• Output current limit: 1.1 A typ (0.5–1.6 A), V1, V2 = 8.4 V
• V1 current, V1 powering OUT: 3.6 μA typ (6.3 μA max), IOUT = 0, V1 = 8.4 V, V2 = 3.6 V
• V2 current, V1 powering OUT: 320 nA typ (650 nA max), V1 = 3.6 V, V2 = 8.4 V
• V2 current in freshness seal mode: 120 nA typ (220 nA max), V1 = GND, V2 = 5 V
• ADJ threshold (falling): 1.032–1.062 V; hysteresis 30–70 mV
• CMP1/CMP2 threshold (falling): 0.378–0.396 V; hysteresis 7.5–12.5 mV
• Break-before-make switchover time: 2.5 μs typ (1–5 μs); input qualification time 64 ms typ (34–94 ms)

Features:

• Selects highest priority valid supply from two inputs
• Blocks reverse and cross conduction currents
• Reverse supply protection to -15 V
• V2 freshness seal / ship mode
• Two auxiliary ±2.3% accurate voltage comparators with open-drain outputs
• V2ON status output
• Overcurrent and thermal protection

Applications:

• Low power battery backup
• Portable equipment
• Point-of-sale (POS) equipment

Package:

• 10-Lead (3 mm × 3 mm) Plastic DFN (LTC4419IDD)
• 12-Lead Plastic Exposed Pad MSOP (LTC4419IMSE, other ordering option)

• n Low Power Battery Backup
• n Portable Equipment
• n Point-of-Sale (POS) Equipment

Depending on the difference between input and output voltages, the LTC4419's internal power dissipation can be high when operating in current limit mode. This usually occurs when a large C OUT is being charged either during initial power up or when OUT switches over to a higher supply. The situation is made worse if a DC load is present on OUT, as this reduces the current available to charge C OUT . In such cases, self heating can cause power path turn-off due to activation of the thermal protection circuitry. The power path is reactivated when die temperature drops to a safe value. This process can repeat indefinitely if C OUT is discharged fully by load current I OUT in the interval when the power path is off.

Maximum allowed C OUT to prevent activation of the thermal protection circuit depends on several factors such as input supply and output voltages, starting ambient temperature, heat dissipation in the PCB and DC output current. Choose COUT < 500μF if possible. If a larger C OUT is necessary, use Figure 11 to choose C OUT. . Follow PCB layout guidelines to improve heat dissipation.

1

0

5

1

0

1

5

2

0

Figure 11. Maximum Allowed C OUT vs Input Voltage for Different T A

The LTC ® 4419 is a dual input monolithic PowerPath™ prioritizer with low operating current, that provides backup switchover for keeping critical circuitry alive during brown out and power loss conditions. Unlike diode-OR products, little current is drawn from the inactive supply even if its voltage is greater than the active supply.

Internal 2Ω, current limited PMOS switches provide power path selection from a primary input (V1) or a backup input (V2) to the output. An adjustable voltage monitor set via an external resistive divider provides flexibility in setting the V1 to V2 switchover threshold. When primary input V1 drops, the ADJ monitor input causes OUT to be switched to V2. Fast non-overlap switchover circuitry prevents both reverse and cross conduction while minimizing output droop.

The LTC4419 has two auxiliary comparators with opendrain outputs that provide flexible voltage monitoring. The V2ON output indicates if V2 is powering OUT. Freshness seal mode prevents V2 battery discharge during storage or shipment.

L , L T, L TC, L TM, Linear Technology and the Linear logo are registered trademarks and PowerPath and ThinSOT are trademarks of Analog Devices, Inc. All other trademarks are the property of their respective owners.