DEMO C IR C U IT DC 1 2 1 0 A
LTC4090
Q u ic k S ta rt G u id e
LTC 4 0 9 0
U S B P o w e r Ma n a g e r w ith 2 A
H ig h V o lta g e B u c k R e g u la to r
B u c k Io n / P o ly m e r C h a rg e r
2A buck regulator w ith 6-38V (60V max) input range and
w ith output voltage tracking battery voltage, f f
ull eatured
battery charger w ith 4.2V f
loat,USB pow er manager that
ensures compliance w ith the USB pow er specif
ication
and a pow er path manager f the battery.
or
DESCRIPTION
Demonstration circuit DC1210A is high voltage sw itching
buck regulator,USB Pow erpath controller and Li-Ion bat-
tery charger. It is based on the LTC4090 and provides
the f
ollow ing f
unctions:
PERF ORM A NCE SU M M A RY
PARAM ETER
Input Supply Range - USB
Input Supply Range - HVIN
HVIN Overvoltage Lockout Threshold
Battery Charger
I
CHG
Charging current
V
FLOAT
V
BAT
Regulated Output Voltage
I
TRKL
Trickle Charge Current
∆V
RECHRG
Recharge threshold
I
nput Current
I
LIM
Input current 100mA mode
I
LIM
Input Current 500mA mode
I
IN(SUSP)
Suspend M ode Input Current
SYM BOL
V
IN
V
HVIN
V
OVLO
Specifications are at TA = 25°C
CONDI ONS
TI
(W ithstands up to 60V w ithout damage)
MI
N
4.35
6
38
650
4.165
49
-65
86
452
TYP
M AX
5.5
60
45
750
4.235
84
-135
105
500
100
UNI
TS
V
V
V
mA
V
mA
mV
mA
mA
µA
41.5
700
4.200
70
-100
93
476
50
V
HVIN
= 12V,V
BAT
= 3.6V ,R4 = 71.5kΩ
I
BAT
= 2mA
V
BAT
= 2V
Threshold Voltage Relative to V
FLOAT
HPW R = 0V,R3 = 2.10kΩ
HPW R = 5V,R3 = 2.10kΩ
SUSP = 5V
OPERA TING PRINCIPL ES
Demo board DC1210A is based on the LTC4090. This
chip manages the pow er supplies that w ould be typical
f a USB pow ered device. Pow er is input f
or
rom either the
USB cable or f
rom a high voltage ( 6V-38V) HVIN input
to an intermediate voltage bus.
The intermediate voltage bus is pow ered f
rom USB or
HVIN w hen available, and f
rom the battery via an ideal
diode. The battery charger is a CC/ timer terminated
CV
type capable ofcharge currents up to 1.5A
The HVIN input has overvoltage protection to 60V. The
2A buck regulator connected to HVIN operates at 800kHz
and its output voltage is regulated in the range 3.45V to
4.6V, tracking the battery voltage and typically 0.3V
higher to allow most ef icient charging.
f
1
LTC4090
EQ U IPM ENT
8 DVM s
1 DC Supply 0-50V 3A f the HVIN input test
or
1DC Supply 5V 0.5A f the USB input test
or
1 USB cable w ith a M ini-B connector at one end and tw o banana plugs at the other end
1 DC Supply 0-5V 3A
1 Pow er Resistor 2ohm 10W
1 Adj
ustable load 0-2A
G ETTING STA RTED
Ref to Figure 1 f proper measurement equipment
er
or
setup and f
ollow the procedure below :
1.
W ith pow er of, connect the input pow er supplies,
f
meters and output load as show n in Figure 1. For
the USB input, use an adj
ustable 0-5V 0.5A pow er
supply and a cable w ith a U SB M ini-B connector that
plugs into J1. For the HVIN input , use a 0-50V 3A
adj
ustable pow er supply. For simulating the battery,
use a 0-5V adj
ustable pow er supply that can deliver
at least 3A, in parallel w ith a 2Ω
10W
pow er resis-
tor. Attach a 0-2A adj
ustable load to the System
Output.
2.
Check that the j
umpers are in their def positions
ault
as show n in the schematic.
USB Charging
3.
Test of trickle charge current: Set the battery simu-
lator voltage at zero. Set the system load at zero.
Disconnect the HVIN pow er supply f
rom the HVIN
input on the demo board or turn it of . Set the USB
f
ON/ j
OFF umper JP3 in the ON position. Increase the
USB input voltage. The charger should activate and
green LED D3 w ill illuminate to indicate charge. Set
the USB voltage to 5.0V. The battery w ill now be in
trickle charge mode and the charge current should
be in the range 49mA… 84mA.
4.
Test of normal charge current: Slow ly increase the
battery voltage to 3.6V and note that w hen the bat-
tery voltage rises above 2.9V the battery charge cur-
rent w ill increase to 452mA… 500mA.
5.
Test ofinput current limit in 100mA mode:Place the
USB Current j
umper JP2 in the 100mA position and
note that USB current f to 86mA… 105mA.
alls
6.
Test of USB current in Suspend M ode. Set the USB
ON/
OFF j
umper JP3 in the OFF position and check
that the USB current drops to less than 90uA.
7.
Return the USB ON/ j
OFF umper JP3 to the ON posi-
tion and the USB Current j
umper JP2 to the 500mA
position. The USB current should increase to
452mA… 500mA. Increase the system load to
600mA. Note that as the load current becomes
higher than the USB current, discharge current is
f ing f
low
rom the battery to the load. The output
ust
voltage drops to j below the battery voltage 3.6V.
Adapter Charging
8.
Test of operation w ith HVIN input: Connect the ad-
j
ustable 0-50V pow er supply to the demo board
HVIN input, turn it on and slow ly increase the HVIN
voltage. W hen HVIN exceeds about 6V the USB cur-
rent drops to zero and current is draw n f
rom HVIN.
The red LED D3 w ill light up to indicate that the buck
regulator is active. Set the HVIN input voltage at
12V. Note that the battery is now charging w ith
650mA… 750mA current and the output voltage has
increased to about 3.9V. The buck regulator on the
HVIN input is now both charging the battery and
pow ering the load. Increase the system load to 1.3A
and check that the battery charge current does not
drop. (The buck regulator is delivering 1.3A + 0.7A =
2A current).
2
LTC4090
9.
Test of the HVIN input overvoltage protection: In-
crease the HVIN input voltage slow ly and note that
as the voltage exceeds 38V… 45V the input current
w ill drop to zero indicating that the buck regulator
shut dow n due to overvoltage. The System Load is
now pow ered f
rom the battery (and f
rom USB if
available). Decrease the HVIN voltage and observe
that the buckregulator w ill resume normal operation.
10.
Increase the battery voltage and note that the
charge current f to zero w hen the voltage ex-
alls
ceeds 4.167V… 4.215V.
Figure 1. Proper M easurement Equipment Setup
3
LTC4090
4
DSP 与 ARM 处理器
