MAX1541

Part: MAX1540A / MAX1541 — Maxim Integrated Products

Type: Dual Step-Down (Quick-PWM) Controller with Linear Regulator

Description: Dual constant on-time PWM step-down controllers with a 2V (MAX1541) / 5.5V (MAX1540A) to 28V battery input range, 0.7V to 5.5V adjustable outputs, 1% output accuracy, inductor-saturation protection, and an integrated 100 mA linear regulator.

Operating Conditions:

• Battery input voltage (V+): 5.5–28 V (MAX1540A); 2–28 V (MAX1541)
• Bias supply (VCC, VDD on MAX1541): 4.5–5.5 V
• Operating temperature: -40 to +85 °C
• Switching frequency: 170 kHz to 620 kHz selectable (TON pin)
• Output adjust range: 0.7–5.5 V

Absolute Maximum Ratings:

• V+, LDOON to GND: -0.3 V to +28 V
• VCC, ON_ to GND: -0.3 V to +6 V
• CSN_, LX_ to GND: -2 V to +30 V
• Max junction temperature: +150 °C
• Storage temperature: -65 to +150 °C
• Lead temperature (soldering, 10 s): +300 °C

Key Specs:

• Reference voltage: 2.00 V (1.983–2.017 V, VCC = 4.5–5.5 V, TA = 0 to +85 °C)
• FB_ regulation voltage (adjustable): 0.70 V (0.693–0.707 V)
• MAX1540A preset outputs: OUT1 1.8 V/1.2 V; OUT2 2.5 V/1.5 V (±1%)
• MAX1541 preset OUT2: 2.5 V/1.8 V (±1%)
• VCC quiescent current: 0.7 mA typ, 1.5 mA max (FB forced above regulation, LSAT = GND)
• Shutdown current (VCC): <1 µA typ, 5 µA max
• LDO output: 5.0 V typ; 4.70–5.10 V for 0–100 mA load; dropout 500 mV typ, 800 mV max at 50 mA
• Soft-start ramp: 1.7 ms; minimum off-time 400 ns typ (500 ns max)
• Overvoltage trip: +16% typ; undervoltage trip: 70% typ; PGOOD window ±10% typ
• VCC UVLO rising threshold: 4.25 V typ (4.1–4.4 V)
• Thermal shutdown: +160 °C typ (LDOON = GND), hysteresis 10 °C

Features:

• Inductor-saturation protection
• Accurate differential current-sense inputs
• Dual ultra-high-efficiency Quick-PWM controllers with 100 ns load-step response
• MAX1540A: fixed or adjustable outputs and fixed 5 V, 100 mA linear regulator
• MAX1541: external reference input (REFIN1) for dynamically selectable OUT1, optional power-good and fault blanking during transitions, fixed or adjustable 100 mA linear regulator
• 1% VOUT accuracy over line and load
• Overvoltage/undervoltage protection option
• 1.7 ms digital soft-start
• Drives large synchronous-rectifier FETs
• 2 V ±0.7% reference output
• Separate power-good window comparators

Applications:

• Notebook computers
• Core/I/O supplies as low as 0.7 V
• CPU/chipset/GPU with dynamic voltage core supplies (MAX1541)
• DDR memory termination (MAX1541)
• Active termination buses (MAX1541)

Package:

• 32-pin thin QFN, 5 mm x 5 mm (MAX1540A)
• 40-pin thin QFN, 6 mm x 6 mm (MAX1541)

Notebook Computers

Core/I/O Supplies as Low as 0.7V

0.7V to 5.5V Supply Rails

CPU/Chipset/GPU with Dynamic Voltage Core Supplies (MAX1541)

DDR Memory Termination (MAX1541)

Active Termination Buses (MAX1541)

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Maxim Integrated Products

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For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.

(V+ = 15V, VCC = VDD = ON1 = ON2 = 5V, SKIP = GND, LDOIN (MAX1541) = V+, TA = 0°C to +85°C , unless otherwise noted. Typical values are at TA = +25 ° C.)

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Note 1: For the MAX1540A, the gate-driver input supply (VDD) is internally connected to the fixed 5V linear-regulator output (LDOOUT), and the linear-regulator input supply (LDOIN) is internally connected to the battery voltage input (V+).

Stresses beyond those listed under 'Absolute Maximum Ratings' may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

The MAX1540A/MAX1541 feature a thermal fault-protection circuit. When the linear regulator is disabled

(LDOON = GND), the controller sets the thermal limit at +160 ° C. When the linear regulator is enabled (LDOON = VCC), the controller sets the thermal limit at +150 ° C to protect the internal linear regulator from continuous short-circuit conditions. Once the junction temperature exceeds the thermal limit, the thermal-protection circuit activates the fault latch, pulls PGOOD1 and PGOOD2 low, disables the linear regulator, and activates the output discharge sequence of both outputs regardless of the OVP/UVP setting. Toggle ON1 or ON2, or cycle VCC power below 1V to reactivate the controller after the junction temperature cools by 10 ° C.

The MAX1540A standard application circuit (Figure 1) generates a 1.8V and 2.5V rail for general-purpose use in a notebook computer. The MAX1541 Standard Application Circuit (Figure 12) generates a dynamically adjustable output voltage (OUT1), typical of a graphicsprocessor core requirement, and a fixed 2.5V output (OUT2).

See Table 1 for component selections. Table 2 lists the component manufacturers.

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages .)

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