DC1140A Datasheet DC1140A | P1-P3

DESCRIPTION

Demonstration Circuit 1140A is a high efficiency USB

Power/Li-Ion battery manager plus a 1A Buck-Boost

regulator. The LTC3567EUF is available in a 24-pin

(4mm × 4mm) QFN surface mount package.

L, LTC, Burst Mode, Bat-Track are registered trademarks of Linear Technology Corporation.

PowerPath and SwitcherCAD are trademarks of Linear Technology Corporation. Other product

names may be trademarks of the companies that manufacture the products.

PERFORMANCE SUMMARY

Specifications are at T

= 25°C

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

VBUS

Bus Input Voltage Range 4.35 5.5 V

LDO3V3 3.3V LDO Output Voltage Range 3.1 3.4 V

VBAT

Battery Float Voltage Constant Voltage Mode 4.15 4.23 V

BAT

Battery Charge Current Constant Current Mode, R

PROG

= 2.00k

485 515 mA

VOUT1

Regulator 1 Output Voltage IOUT1 ≤ 1000mA 3.15 3.45 V

OPERATING PRINCIPLES

The LTC3567EUF is a full featured USB Power Manager

and Li-Ion battery charger with a 1A Buck-Boost DC/DC

regulator. The LTC3567EUF has an I

C interface that al-

lows adjustment of the Buck-Boost output voltage, oper-

ating mode, and USB power management control. The

Bat-Track™ battery charger pre-regulator ensures the

charger operates at the highest possible efficiency.

The LTC3567EUF is composed of 6 functional blocks, all

working together: USB Power Manager, Pre-regulator,

Battery Charger, Ideal Diode, 1A Buck-Boost DC/DC regu-

lator, and I

USB Power Manager

The USB Power Manager is used to manage the load that

the LTC3567EUF system presents to the USB interface.

The load current can be programmed by changing the

CLPROG resistor (R2), and by setting the operating mode

to 1X, 5X or 10X with the I

C interface.

QUICK START GUIDE FO

DC1140

LTC3567EUF: High Efficiency

USB Power Manager Plus 1A

Buck-Boost Converter with I

C Control

Buck-Boost Re

ulator Efficienc

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1140A

HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER

LTC3567EUF

Pre-Regulator

The pre-regulator is a high efficiency buck regulator that

produces a voltage at VOUT equal to the battery voltage

plus 0.3V. By reducing the voltage across the charger to

0.3V the dissipation in the charger is greatly reduced, as

compared with a linear charger.

Battery Charger

The battery charger operates in constant current mode,

until the battery voltage rises to approximately the FLOAT

voltage, of 4.2V, and then the charger switches to con-

stant voltage mode.

The charge current is programmed by the PROG resistor

(R3), and has been set to 500mA, on DC1140A, with a

2.00k

Ω

resistor. The battery charger implements trickle

charging, for initial battery voltages less than 2.85V. It

also implements a charge termination timeout of 4 hours,

and a bad cell charging timeout of 30 minutes. An NTC

input is used to determine if the battery temperature is

suitable for charging, too hot or too cold.

The statuses of the charger, as well as any faults, are sig-

naled with the

CHRG

pin.

Ideal Diode

The Ideal Diode block is composed of an internal Ideal

Diode implemented with an on die MOSFET, as well as a

MOSFET gate driver that allows the use of a parallel ex-

ternal MOSFET.

When the voltage on VOUT drops more than 15mV below

the voltage at BAT, the Ideal Diode becomes active. This

will happen when VBUS is not present, or the load on

VOUT exceeds the power available from VBUS.

1A Buck-Boost DC/DC regulator

The Buck-Boost DC/DC regulator provides a regulated

output that can be above and below the input voltage.

The battery voltage will vary from VFLOAT (4.2V) to as

low as 2.5V. The Buck-Boost regulator can supply a

regulated 3.3V output over this entire battery voltage

range.

The Buck-Boost is implemented with a full H-bridge

switch, and proprietary control algorithm.

C Interface

The I

C interface is a 100kHz, write only serial interface

that allows control of the USB input current limit, battery

charger on/off, Buck-Boost regulator (VOUT1) on/off,

Buck-Boost regulator operating mode, and Buck-Boost

output voltage via an internal 4 bit DAC.

Figure 1.

VOUT1 startup

Figure 2.

SWAB1 switching waveform

VOUT1

EN1

IOUT1 = 100mA

Figure3. SWCD1 switching waveform

IOUT1 = 100mA

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1140A

HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER

LTC3567EUF

APPLICATIONS INFORMATION

The parasitic inductance in some USB cables may cause

the VUSB voltage to overshoot at plug in. If this is the

case it is recommended that the network of C1, R1 and

C2 be added to the board to damp out this overshoot.

While, at first glance, it may appear that C1 + C2 exceeds

the USB specification for capacitive load on VUSB, in fact

this is not the case. For most MLCC capacitors, with

X7R/X5R dielectric the capacitance will be below 4.7μF,

for DC biases of 5V.

The battery charger must see low impedance to ground,

which is the case when a battery is attached. In the event

that a battery emulator is being used, or the impedance to

ground is above 0.5

Ω

, the circuit of C7 and R14-16 is

recommended.

The Buck-Boost regulator should be compensated with a

Type III compensator, as shown on the schematic. The

Buck, Buck-Boost and pure Boost regions of operation

have different poles/zeroes and PWM gains. In particular,

the Buck-Boost and pure Boost regions have a RHP zero,

that must be accommodated.

It is recommended that the stabilization be verified in all

three regions of operation, with minimum and maximum

load.

The /CHRGEN and EN1 pins are wire OR’ed with the cor-

responding bits from the I

C channel. Consequently, if

they are high the battery charger will be disabled and

VOUT1 will be enabled. This is true regardless of the

state of the I

C bits. If control of the battery charger and

VOUT1 through the I

C bits is desired, please ensure that

these pins are held low.

P1-P3 P4-P6 P7-P8

DC1140A

Mfr. #:

Buy DC1140A

Manufacturer:

Analog Devices Inc.

Description:

Power Management IC Development Tools LTC3567EUF - High Efficiency USB Power M

Lifecycle:

New from this manufacturer.

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DC1140A