MAX77986DEFD+ 19VIN, 5.5A High-Efficiency Switching Charger with Smart Power Selector and OTG

1. Product Overview

2. Key Features

Charging Performance

• Fast Charging: Up to 5.5A programmable charge current (100mA to 5500mA in 50mA steps)
• High Efficiency: 92% buck efficiency at 4A/12V input, 92% charging efficiency at 3.5A/9V
• Wide Input Range: 4.7V to 19V operating, +28V absolute maximum rating
• Battery Support: Li-ion, Li-polymer, LiFePO4 chemistries
• Termination Voltage: Programmable 4.15V to 4.5375V (A variant) or 3.5V to 4.275V (B variant)

Smart Power Selector™

• Seamless power distribution between adapter, battery, and system
• Supplemental mode: Battery provides extra current when adapter is insufficient
• System can start with dead, missing, or deeply discharged battery
• True battery disconnect FET (RDSON = 7.7mΩ)

Reverse Boost (OTG)

• Programmable output voltage: 5V to 12V (100mV steps)
• Max output current: 3.1A (clamped at 18W power limit)
• True load disconnect in boost mode
• Programmable output current protection

Protection & Safety

• JEITA-compliant temperature-based charging
• Thermal regulation and thermal shutdown (155°C threshold)
• Input overvoltage (19.5V), undervoltage, and current limiting
• Battery overcurrent protection (3A to 10A programmable)
• Charge safety timer (3-8 hours programmable)
• Short-circuit protection

Advanced Features

• Spread spectrum modulation (±4%, ±8%, ±16%) for EMI reduction
• Fast unplug detection for 5V, 9V, and 15V sources
• I²C programmable interface (1MHz standard/fast mode, up to 3.4MHz HS-mode)
• Factory ship mode for minimal battery leakage
• Differential remote voltage sensing (BATSP/BATSN)

3. Electrical Specifications

3.1 Absolute Maximum Ratings

3.2 Recommended Operating Conditions

3.3 Key Electrical Characteristics

Input Current Limit (MAX77986)

• Range: 0.1A to 5.5A (50mA steps)
• Default: 500mA
• Accuracy: -3.5% to +3.5% (≥500mA, -5°C to +85°C)
• Charge Current
• Precharge: 40-80mA
• Trickle: 270-330mA (when TKEN=1)
• Fast Charge: 0.1A to 5.5A programmable
• Top-off: 150-850mA programmable
• Switching Frequency
• Selectable: 1.3MHz or 2.6MHz
• Inductor: 1.0μH for 1.3MHz, 0.47μH for 2.6MHz
• Thermal Regulation
• Programmable threshold: +85°C to +130°C (5°C steps)
• Default: +115°C
• Gain: -315mA/°C (reduces current by 5.73% per °C above threshold)

4. Pin Configuration and Functions

4.1 Package Outline (32-Pin FC2QFN)

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TOP VIEW (Bumpside Down)
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       ║  1  2  3  4  5  6  7  8  ║
       ║  9 10 11 12 13 14 15 16  ║
       ║ 17 18 19 20 21 22 23 24  ║
       ║ 25 26 27 28 29 30 31 32  ║
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4.2 Pin Descriptions

5. Functional Description

5.1 Smart Power Selector Operation

The IC manages power flow between CHGIN, BYP, SYS, and BATT through integrated switches:

• QCHGIN: Input switch with current limiting
• QHS/QLS: DC-DC converter switches (buck/boost)
• QBATT: Battery-to-system switch with overcurrent protection
• Power Priority (with valid adapter):

1. Energy delivery to BYP (highest)
2. Energy delivery to SYS (second)
3. Battery charging (remaining capacity)
4. Power Priority (battery only):

• Battery supplies SYS and BYP (if boost enabled)

5.2 Charging States

1. No Input Power/Idle: Charger off, system powered by battery
2. Precharge: VBATT < 2.5V, 40-80mA current
3. Trickle Charge: 2.5V ≤ VBATT < 3.1V, 270-330mA (if TKEN=1)
4. Fast-Charge CC: Constant current, max 5.5A
5. Fast-Charge CV: Constant voltage at VBATTREG
6. Top-off: Current < ITO for tTERM
7. Done: Charging complete, 0mA current
8. Timer Fault: Safety timeout (tPQ or tFC exceeded)
9. Thermal Shutdown: TJ > 155°C

5.3 Reverse Boost (OTG) Mode

• MODE = 0x0A: Boost converter active, regulates VBYP to VBYPSET (5V-12V)
• QCHGIN Closed: Allows current sourcing from CHGIN up to OTG_ILIM limit
• Power Ceiling: 18W maximum (MAX77986)
• Protection: Overcurrent fault latch with optional auto-retry

5.4 Battery Overcurrent Protection

• Threshold: Programmable 3.0A to 10.0A (0.5A steps) via B2SOVRC[3:0]
• Response Time: 105μs (fast) or 10ms (delayed) debounce
• Action: Opens QBATT, shuts down buck, generates interrupt
• Retry: Auto-retry after 150ms if RECYCLE_EN=1

6. I²C Interface and Register Map

6.1 I²C Slave Address

• 7-bit: 0x6B (1101011b)
• Write: 0xD6
• Read: 0xD7

6.2 Key Configuration Registers

7. Typical Application Circuit and Layout

7.1 Application Schematic

CHGIN ── 2.2μF ── PGND
   │
BYP ── 2×22μF + 100nF ── PGND
   │
LX ←── Inductor (1μH @ 1.3MHz) ── SYS ── 2×22μF ── PGND
   │
BATT ── 2×10μF ── PGND
   │
BATSP/BATSN → Kelvin sense to battery terminals
   │
THM ── NTC Thermistor ── AGND
   │
VDD ── 1μF ── AGND
PVDD ── 1μF ── PGND
VIO ── 1μF ── AGND

7.2 Critical Layout Guidelines

1. Ground Separation: Keep AGND/DGND isolated from PGND; connect at single point near input capacitor
2. Bypass Capacitors: Place CHGIN, BYP, SYS, and BATT capacitors as close as possible to IC pins
3. High Current Paths: Use wide, short traces for CHGIN, BYP, SYS, BATT, LX, and PGND
4. Kelvin Sensing: Route BATSP/BATSN directly to battery terminals; avoid vias and shared traces
5. Thermal Design: Use exposed pad connection to PGND plane for heat dissipation
6. Inductor Placement: Minimize LX trace length to reduce EMI

8. Ordering Informatio

9. Document Information

• Datasheet Revision: 3 (February 2025)
• Document Number: 19-101295
• For Chip Revision: PASS2 (0b010) - Contact Analog Devices for PASS1 (0b001) details
• CHIP_ID Register: 0x86 for MAX77986
• CHIP_REVISION Register: 0xA (A variant) or 0xB (B variant)