MP2639A datasheet(21/35 Pages) MPS

21 / 35 page

MP2639A

– SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION

MP2639A Rev. 1.0

www.MonolithicPower.com

6/6/2017

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

Table 2: Operation Mode

VBATT Rising, Quit Linear

Down Mode

(enter switch down mode)

VH > VL - 114mV

VBATT Falling, Enter Linear

Down Mode

(quit switch down mode)

VH < VL - 342mV

VBATT Rising, Quit Switch

Down Mode

(enter normal switch mode)

VH > VL + 400mV

VBATT Falling, Enter Switch

Down Mode

(quit normal switch mode)

VH < VL + 114mV

Battery Charge Profile

The MP2639A provides three main charging

phases: trickle-current, constant-current charge,

and constant-voltage charge (see Figure 5).

Trickle charge

Charge Current

Battery Voltage

Constant Voltage Charge

CC Fast Charge

Charge Full

VBATT_FULL

VBATT_LOW

IBF

ITC

ICC

Figure 5: Battery Charge Profile

1. Phase 1 (trickle-current charge): When the

battery voltage is lower than VBATT_LOW, the

MP2639A applies a safe trickle-charge

current (ITC) to the deeply depleted battery

until the battery voltage reaches trickle

charge

the

fast

charge

threshold

(VBATT_LOW). If VBATT_LOW is not reached

before the trickle-charge timer expires, the

charge

cycle

ceased,

and

corresponding

timeout

fault

signal

asserted. See the Safety Timer section on

page 21 for more detail.

2. Phase 2 (constant-current charge): When

the battery voltage exceeds VBATT_LOW, the

MP2639A stops the trickle-current charge

phase and enters constant-current charge

(fast charge) phase with a soft start. The

fast charge current can be programmed via

ISET.

3. Phase 3 (constant-voltage charge): When

the battery voltage rises to the charge-full

voltage (VBATT_FULL), the charge current

begins to taper off. The charge cycle is

considered complete when the CV loop is

dominated, and the charge current reaches

the battery-full termination threshold. A

500μs force charge time is designed for

each charge cycle. After the 500μs force

charge time expires, the charge full signal is

allowed to assert.

If IBF is not reached before the safety charge

timer expires, the charge cycle is ceased,

and the corresponding timeout fault signal is

asserted. See the Safety Timer section for

more detail.

A new charge cycle starts when the following

conditions are valid:



The input power is re-plugged.



MODE is toggled from high to low.



No thermistor fault at NTC.



No safety timer fault.



No battery over-voltage.

Automatic Recharge

When the battery is fully charged and the

charging is terminated, the battery may be

discharged for system consumption or self-

discharge. The MP2639A starts a new charging

cycle automatically without requiring a manual

restart of a charging cycle.

Charge Current Setting

ISET is used to program the charge current.

The setting formula is shown in Equation (2):







CHG

ISET

640(k )

(A)

(2)

Battery Over-Voltage Protection (OVP)

The MP2639A is designed with a built-in battery

over-voltage limit of 103.3% of VBATT_FULL. When

battery

over-voltage

event

occurs,

the

MP2639A suspends the charging immediately.

Non-Sync Mode

When the input current at the VL side is lower

than 330mA, the MP2639A turns off Q1 and

switches to non-sync operation.

MP2639A Datasheet(PDF) 21 Page - Monolithic Power Systems

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