BQ25628ERYKR Datasheet & Specs: I2C Buck Battery Charger IC – Pinout + Buy

The BQ25628ERYKR is Texas Instruments’ single-cell, 2-A, switch-mode (buck) battery charger with an I2C interface and integrated NVDC power-path management, in an 18-pin WQFN. It charges one Li-ion or Li-polymer cell from inputs up to 18 V, integrates all four power FETs, and keeps the system rail alive even when the battery is depleted or removed. This page covers the datasheet specs, the pinout, the BQ25628 vs BQ25629 distinction, and how to source the part.

BQ25628ERYKR Key Specs at a Glance

• Function: 1-cell Li-ion/Li-Po switch-mode (buck) charger plus NVDC power path, over I2C
• Charge current: up to 2.0 A
• Input: up to 18 V maximum; VINDPM input-voltage limit 3.8 V to 16.8 V (4.6 V default)
• Integrated FETs: reverse-block (RBFET), high-side and low-side switches, and a 15 mΩ BATFET
• Switching: 1.5 MHz synchronous buck; PFM at light load; >90% efficiency
• Low power: ultra-low 0.15 uA ship mode; integrated ADC for telemetry
• Package / variant: 18-pin WQFN 2.5 x 3.0 mm; the “E” variant omits the OTG (boost) output

What Is the BQ25628ERYKR?

The BQ25628E is a complete single-cell charging front end. Instead of a linear charger that burns the input-to-battery voltage difference as heat, it uses a synchronous buck converter, so it stays efficient even when the input is well above the battery voltage. It integrates the four power FETs a charger needs – a reverse-blocking input FET, the high-side and low-side switching FETs, and a low-resistance BATFET between system and battery – which keeps the external BOM down to an inductor and a handful of capacitors.

The other half of the chip is NVDC (narrow VDC) power-path management. It powers the system rail directly from the input while charging the battery in parallel, regulating the system slightly above the battery voltage but never below a programmable minimum. That is what gives a product instant-on behavior: even with a dead or missing battery, the system still boots from the adapter. The I2C interface lets the host set charge current, voltage, input limits, and safety behavior, while the device can also run a default charging cycle autonomously.

On the order number: the E marks the variant without the OTG (boost) output, the RYK is the 18-pin WQFN package, and the trailing R in BQ25628ERYKR denotes tape-and-reel. The closely related BQ25628 adds an OTG output, and the BQ25629 adds USB host/charging-port detection.

BQ25628ERYKR Specifications (Datasheet Summary)

Parameter	BQ25628ERYKR (BQ25628E)
Battery	Single-cell (1S) Li-ion / Li-polymer
Topology	Synchronous buck (switch-mode) charger + NVDC power path
Max charge current	2.0 A
Input voltage (max)	18 V
VINDPM range	3.8 V to 16.8 V (4.6 V default)
Integrated FETs	RBFET, HSFET, LSFET, 15 mΩ BATFET
Switching frequency	1.5 MHz
Light-load mode	PFM
Ship-mode current	~0.15 uA
Interface / telemetry	I2C; integrated ADC; STAT and INT outputs
Battery temp safety	TS thermistor monitoring (JEITA profile)
Protection	Input OVP, UVLO, thermal regulation + shutdown, battery OCP
Package	18-pin WQFN, 2.5 x 3.0 mm

BQ25628ERYKR Pinout and Pin Functions (18-Pin WQFN)

The pins group into the power stage, the battery/system path, and the control and sense lines:

Pin / group	Function
VBUS / PMID	Input from adapter/USB and the input-FET midpoint node
SW / BTST	Buck switch node and bootstrap capacitor for the high-side gate
SYS	Regulated system output (powered by input or battery)
BAT	Battery connection (through the internal BATFET)
REGN	Internal LDO bias output (decoupling cap)
ILIM	Sets the default input current limit
TS / TS_BIAS	Battery thermistor input and its bias for the JEITA profile
SCL / SDA	I2C control interface
INT / STAT / PG	Interrupt, charge-status, and power-good indications
GND / PowerPAD	Ground and thermal pad

Buck vs Linear Charging and the NVDC Power Path

Why a buck charger rather than a simple linear one? A linear charger dissipates (Vin – Vbat) times the charge current as heat. From a 5 V port into a 3.7 V cell at low current that is tolerable, but from a 9 V or 12 V adapter, or at 2 A, the heat becomes the limiting factor and the package cannot shed it. The BQ25628E’s buck converter steps the voltage down efficiently instead of burning it, which is why it can take an 18 V input and still charge at 2 A without cooking.

NVDC power-path management is the second reason designers reach for this class of part. Because the system is fed directly and held above a minimum voltage, the product runs the instant an adapter is connected, charges the battery with whatever current is left over, and automatically draws supplemental current from the battery during load peaks the adapter cannot cover. The trade-off versus a linear charger is more external components (the inductor and its layout) and switching-noise management – the price of the efficiency and the always-on system rail.

BQ25628ERYKR Applications

The BQ25628E suits compact, battery-powered products that charge from USB or an adapter: wearables and hearables, portable and wearable medical devices, IoT sensor nodes, handheld instruments and point-of-sale units, and smart-home gadgets. Anywhere a single Li-ion cell must charge efficiently while the system stays powered, this NVDC buck charger fits. These dense, mixed-signal boards are typical power supply PCB work, and our components sourcing team can supply the charger and the surrounding power components together.

BQ25628E vs BQ25628 vs BQ25629 (and Linear Chargers)

Within the family the differences are about the output and input features, not the core 2 A buck charger:

Device	OTG/boost	Input detection	Notes
BQ25628E (this part)	No	ILIM pin	Buck charger + NVDC, no boost output
BQ25628	Yes	ILIM pin	Adds OTG (boost) output
BQ25629	Yes	USB host/charging-port	USB 2.0/3.0 compliant, OTG up to 2 A
Linear charger	No	Simple	Cheaper/smaller; lossy at high Vin

A useful, slightly counterintuitive point: a switch-mode charger is not automatically the right choice. For a low-current charge from a fixed 5 V port, a linear charger is smaller, cheaper, and quieter. The BQ25628E earns its keep when the input voltage is higher than 5 V (9-18 V adapters), when the charge current is high, or when you need the always-on system rail from NVDC. Choose by input voltage, current, and the power-path requirement – not by assuming buck beats linear.

How to Buy the BQ25628ERYKR (Packaging and Sourcing)

Order the BQ25628ERYKR for the 18-pin WQFN on tape-and-reel. As a relatively new charger, it faces less SEO competition than a commodity part – useful for ranking – but it also has fewer drop-in second sources, so plan the design around it. Buy from traceable channels, and let our components sourcing team confirm authenticity and availability. The WQFN has a thermal pad that carries the charge-path heat, so plan for SMT assembly with proper paste coverage, and X-ray inspection to confirm the pad is soldered without voids – at 2 A, the thermal joint matters.

BQ25628E Design and Assembly Mistakes to Avoid

• Wrong inductor or output capacitor for the 1.5 MHz buck. Follow the datasheet values; an out-of-spec inductor hurts efficiency and can destabilize the loop.
• Long, high-impedance BAT and SYS routing. Keep the power path short and wide, and Kelvin-sense where the datasheet calls for it.
• A mismatched TS thermistor network. The JEITA temperature folding depends on it – wrong resistor values mean wrong charge behavior at temperature.
• Forgetting that defaults differ from your target. Set VSYSMIN, charge current, and input limits over I2C rather than assuming the power-on defaults.
• A starved thermal pad. Use a copper pour with vias under the WQFN and verify by X-ray; the package sheds 2 A of charging heat through that pad.
• Ignoring moisture sensitivity; bake per J-STD-033 if reels were open or stored a long time before reflow.

Frequently Asked Questions About the BQ25628ERYKR

What is the difference between the BQ25628 and BQ25629?

Both are 2 A single-cell buck chargers. The BQ25629 adds USB host and charging-port detection and meets USB 2.0/3.0 power specs with OTG up to 2 A; the BQ25628 has an OTG output without that USB detection. The BQ25628E variant omits the OTG output entirely.

What does the “E” in BQ25628E mean?

It denotes the variant without the OTG (boost) output. If your design never needs to source power out to an accessory, the BQ25628E is the simpler, charge-only option.

Buck or linear charger – which should I use?

Use a buck charger like the BQ25628E for higher input voltages (above 5 V), higher charge currents, or when you need the NVDC always-on system rail. Use a linear charger for the smallest, cheapest low-current charge from a fixed 5 V source.

What is the maximum charge current of the BQ25628ERYKR?

Up to 2.0 A into a single-cell battery, set and limited over I2C. Input current and voltage limits (IINDPM/VINDPM) automatically reduce charge current when the source cannot supply more.

Does it work with a dead or removed battery?

Yes. NVDC power-path management regulates the system above a programmable minimum voltage straight from the input, so the product powers up and runs even with a fully depleted or absent battery.

What package is the BQ25628ERYKR?

An 18-pin WQFN measuring 2.5 x 3.0 mm with a thermal pad. It is a bottom-terminated package, so X-ray after reflow is the reliable way to verify the joints and the pad.

Sourcing the BQ25628ERYKR for Your Power Design

The BQ25628ERYKR packs an efficient single-cell charger and an always-on power path into one small package – provided it is genuine and its thermal pad is soldered properly. Send us your part list or BOM and we’ll confirm BQ25628ERYKR stock, verify authenticity, and quote the assembled board.