DESCRIPTION
Demonstration Circuit 1132A is a high efficiency USB
Power/Li-Ion battery manager plus a 1A Buck-Boost
regulator. The LTC3566EUF 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
A
= 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
BUS
Bus Input Voltage Range 4.35 5.5 V
V
OUT
Output Voltage Range Range is mode and load dependant
3.5 4.6 V
V
BAT
Output Float Voltage Constant voltage mode
4.2 V
I
BAT
Output Charge Current Constant current mode 0.5 1 A
VOUT1 Buck-Boost Output Voltage 3.25 3.30 V
IOUT1 Buck-Boost Output Current 1 A
OPERATING PRINCIPLES
The LTC3566EUF is a full featured USB Power Manager
and Li-Ion battery charger with a 1A Buck-Boost DC/DC
regulator. The Bat-Track™ battery charger pre-regulator
ensures the charger operates at the highest possible effi-
ciency.
The LTC3566EUF is composed of 5 functional blocks, all
working together: USB Power Manager, Pre-regulator,
Battery Charger, Ideal Diode, and 1A Buck-Boost DC/DC
regulator.
USB Power Manager
The USB Power Manager is used to manage the load that
the LTC3566EUF 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 ILIM1, ILIM0 jumpers.
DEMO CIRCUIT DC1132
A
Quick Start Guid
e
LTC3566EUF: High Efficiency
USB Power Manager Plus 1A
Buck-Boost Converte
r
Buck-Boost Re
g
ulator Efficienc
y
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC1132A
HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER
LTC3566EUF
2
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 DC1132A, 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 tempera-
ture is suitable for charging, too hot or too cold.
The status 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 be-
low 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.
Figure 1.
VOUT1 startup
Figure 2.
SWAB1 switching
Figure 3.
SWCD1 waveform
VOUT1
EN1
IOUT1 = 100mA
IOUT1 = 100mA
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC1132A
HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER
LTC3566EUF
3
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 im-
pedance to ground is above 0.5
Ω
, the circuit of C5 and
R8-10 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.
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC1132A
HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER
LTC3566EUF
4
QUICK START PROCEDURE
Using short twisted pair leads for any power
connections and with all loads and power sup-
plies off, refer to Figures 4 and 5 for the proper
measurement and equipment setup. Follow the
procedure below:
1. Set PS1 to 5V, and PS2 to 3.6V.
2. Observe IVBUS (AM1). The USB input cur-
rent limit is programmed for 1X (100mA), but
the battery charge current is programmed to
500mA. So the USB input current limit is ac-
tivated, and the charger cannot get enough
current to charge at 500mA. Consequently,
VCLPROG is at ~1.15V, but VPROG cannot rise
to 1V.
3. Set ILIM1 (JP2) to “HI” and ILIM0 (JP3) to
“HI”. Observe IVBUS (AM1). The USB input
current limit is now 5X (500mA), and the
charger can get enough current to charge
the battery at 500mA. Consequently,
VCLPROG is nearly 1.15V, and VPROG is at 1V.
4. Set ILIM1 (JP2) to “LO”. Observe IVBUS
(AM1), VCLPROG (VM6) and VPROG (VM5).
The USB input current limit is now 10X (1A),
and the charger can get enough current to
charge the battery at 500mA. Consequently,
VCLPROG is at 0.6V (0.5 * 1.15V), and VPROG
is at 1V.
5. Set PS1 to 0V, and LOAD1 to 1A. Observe
VOUT (VM2) and V(BAT,OUT). Verify that 3.55V
< VOUT < 3.60V, and (VBAT - VOUT) <
0.05V. The USB input voltage is off causing
VOUT to fall. When VOUT falls to 15mV be-
low VBAT, the LTC3566 activates the ideal
diode and supplies current to VOUT from the
BAT pin.
6. Set LOAD1 to 400mA and PS1 to 5V. Ob-
serve VOUT (VM2), VCLPROG (VM6) and
VPROG (VM5). The USB input current limit is
10X (1A), and the charger can get enough
current to charge the battery at 500mA. In
addition, VOUT is being loaded at 400mA,
producing an aggregate load at VBUS of
nearly 860mA. Consequently, VCLPROG is
nearly 1.15V, and VPROG is at 1V.
7. Observe VOUT (VM2) and VOUT1 (VM4).
The Buck-Boost regulator has been en-
abled at no load. The nominal output volt-
age on the Buck-Boost regulator is 3.3V.
8. Leave LOAD1 at 400mA, and set LOAD2 to
400mA. Observe VOUT (VM2), VOUT1
(VM4) and VCLPROG (VM6). The USB input
current limit is 10X (1A), and the charger can
get enough current to charge the battery at
500mA. In addition, VOUT1 is being loaded
at 400mA, producing an aggregate load at
VBUS of nearly 860mA. Consequently,
VCLPROG is nearly 1.15V, and VPROG is at 1V.
9. Set
CHRGEN
(JP4) to “HI”. Set LOAD2 to 1A.
Observe VOUT (VM2), VOUT1 (VM4), and
VCLPROG (VM6). The USB input current limit
is 10X (1A), and the charger is off. In addi-
tion, VOUT1 is being loaded at 1A, produc-
ing an aggregate load at VBUS of nearly
860mA. Consequently, VCLPROG is nearly
1.15V, and VPROG is at 1V.
10. Set LOAD2 to 0A, and
CHRGEN
(JP4) to “LO”.
Set NTC (JP6) to “EXT”.
CHRG
LED should
flash. The charger is now enabled, but the
voltage is indicating that the battery tem-
perature is very cold.
11. Set NTC (JP6) to “INT” and EN1 (JP1) to
“ON”.
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC1132A
HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER
LTC3566EUF
5
Figure 4. Proper Measurement Equipment Setup for DC1132A
VIN
GND
Figure 5. Measuring Input or Output Ripple
PS1 +
0V-6V supply
2A -
+ -
-
+
+ LOAD2
0V-5V
- 2A
+
-
+ -
AM1
VM1
VM4 AM4
+ PS2
0V-5V supply
- 2A
+ -
-
+
AM3
VM3
-
+
VM6
-+
VM5
3.6Ω
+ LOAD1
0V-5V
- 2A
-
+
+ -
VM2
AM2
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC1132A
HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER
LTC3566EUF
6
Figure 6. DC1132A Schematic
VFLOAT=4.2V
R13
121k
R17
0
E7
GND
R5
100K
R11
15k
TP2 D+
R7
0
3.3V
C4
0.1uF
16V
1.25A
VBUS
L1
2.2uH
LPS4018-222MLC
C11
1uF
10V
JP1
E13
VOUT
JP2
TP3 ID
HI
C6
330pF
5%
E3
CLPROG
1
0
3.3V
C1
10uF
16V
0805
JP4
E9
GND
R12
105k
ILIM0
R6
0
R9
1.0
5%
USBMINI-B
J1
1
2
3
4
5
VBUS
D-
D+
ID
GND
D1
GREEN
CHGR
12
500mA (5X)
E15
LDO3V3
E8 BAT
CHRGEN
LO
0
C5
100
6.3V
1206
20%
C10
22uF
6.3V
0805
20%
E5
NTC
C3
22uF
6.3V
0805
R4
100K
TP4
INJ
R15
20
5%
1A (10X)
0
E14
GND
JP5
VBUS
TP1 D-
E4
PROG
OFF
U1
LTC3566EUF
21
20
2
15
3
16
11
1
19
18
22
24
23
13
17
8
14
9
10
7
126
4
5
25
VBUS
VOUT
CLPROG
PROG
NTC
CHRG
SW CD1
LDO3V3
BAT
GATE
SW
EN1
CHRGEN
ILIM0
GND
MODE
ILIM1
VIN1
VOUT1
SWAB1
GNDGND
FB1
VC1
GND OPT
HI
E10
VOUT1
J2
DF3-3P-2DSA
1
2
3
BAT
GND
NTC-EXT
1
ILIM1
PWM
OPT
JP3
ILIM1
1
INT
1
U nle ss n ot ed :
R e sistor s: Ohm s, 04 02 , 1%, 1/16W
Ca p ac i to rs: uF, 0402, 10%, 50V
ON
TP5
VOUT
R2
3.01k
E12
GND
C8
33pF
5%
MODE
USB
E11
CHRG
EXT
C7
10pF
+/-0. 5pF
EN1
VBUS
3.5V-4.6V
JP6
500mA
CURRENT LIMIT
R10
1.0
5%
LO
INPUT CURRENT LIMIT SETTINGS
BURS T
SUSPEND (500uA)
HI
25mA
ILIM0
NTC
R1
1.0
5%
0
R14
324k
E2
GND L2
3.3uH
LPS4018-332MLC
C2
10uF
16V
0805
LO
R16
1k
5%
0603
Q1
Si2333DS
1
3 2
100mA (1X)
1A
E1
VBUS
4.35V-5. 5V
E6
GND
R3
2K
R8
1.0
5%
C9
22uF
6.3V
0805
20%
VOUT
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC1132A
HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER
LTC3566EUF
7
Figure 7. DC1132A BOM
