Linear Technology DC1210A Quick Start Manual
LTC4090
1
V
V
V
A
V
A
V
A
mA
µA
DEMO
C IR C U IT
DC1 2 1 0
A
Q u ic k S ta rt G u id e
L T C 4 0 9 0
2 A
H ig h V o lta g e B u c k R e g u la to r
DESCRIPTION
U S B P o w e r Ma n a g e r w ith
Demonstration circuit DC1210A is high voltage sw itching
buck regulator, USB Pow erpath controller and Li-Ion battery charger. It is based on the LTC4090 and provides
the follow ing functions:
2A buck regulator w ith 6-38V (60V max) input range and
w ith output voltage tracking battery voltage, full featured
battery charger w ith 4.2V float, U SB pow er manager that
ensures compliance w ith the USB pow er specification
and a power path manager for the battery.
PERF ORM A NCE SU M M A RY
SYM BO L PARAM ETER CONDITIO NS M IN TYP M AX UNITS
V
IN
V
HVIN
V
OVLO
I
CH G
V
FLOAT
I
TRKL
∆
V
RECH R G
I
LIM
I
LIM
I
IN(SUSP)
Input Supply Range - USB
Input Supply Range - HVIN (W ithstands up to 60V without damage) 6 60
HVIN O vervoltage Lockout Threshold 38 41.5 45
Battery Charger
Charging current V
V
Regulated O utput Voltage I
BAT
Trickle Charge Current V
Recharge threshold Threshold Voltage Relative to V
Input Current
Input current 100mA mode HPW R = 0V, R 3 = 2.10k
Input Current 500mA mode HPW R = 5V, R 3 = 2.10kΩ 452 476 500
Suspend M ode Input Current SU SP = 5V 50 100
Specifications are at TA = 25°C
= 12V, V
HVIN
= 2mA 4.165 4.200 4.235
BAT
= 2V
BAT
BAT
= 3.6V , R4 = 71.5k
FLOAT
Ω
Ω
-65 -100 -135 m
4.35 5.5
650 700 750 m
49 70 84 m
86
93 105 m
OPERA TING PRINCIPL ES
Demo board DC1210A is based on the LTC4090. This
chip manages the pow er supplies that w ould be typical
for a USB pow ered device. Pow er is input from either the
USB cable or from a high voltage ( 6V-38V) H VIN input
to an intermediate voltage bus.
The intermediate voltage bus is pow ered from USB or
HVIN w hen available, and from the battery via an ideal
diode. The battery charger is a CC/CV timer terminated
type capable of charge currents up to 1.5A
The H VIN 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 efficient charging.
LTC4090
2
EQ U IPM ENT
8 DVM s
1 DC Supply 0-50V 3A for the HVIN input test
1DC Supply 5V 0.5A for the U SB input test
1 USB cable with 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 R esistor 2ohm 10W
1 Adjustable load 0-2A
G ETTING STA RTED
Refer to Figure 1 for proper measurement equipment
setup and follow the procedure below :
1. W ith pow er off, connect the input pow er supplies,
meters and output load as show n in Figure 1. For
the U SB input, use an adjustable 0-5V 0.5A pow er
supply and a cable with a U SB M ini-B connector that
plugs into J1. For the H VIN input , use a 0-50V 3A
adjustable pow er supply. For simulating the battery,
use a 0-5V adjustable pow er supply that can deliver
at least 3A, in parallel w ith a 2
tor. Attach a 0-2A adjustable load to the System
Output.
2. Check that the jumpers are in their default positions
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 H VIN pow er supply from the H VIN
input on the demo board or turn it off. Set the USB
ON /O FF jumper JP3 in the O N 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 battery voltage rises above 2.9V the battery charge current w ill increase to 452mA… 500mA.
Ω 10
W pow er resis-
5. Test of input current limit in 100mA mode: Place the
USB Current jumper JP2 in the 100mA position and
note that U SB current falls to 86mA… 105mA.
6. Test of USB current in Suspend M ode. Set the USB
ON /O FF jumper JP3 in the O FF position and check
that the USB current drops to less than 90uA.
7. Return the USB O N/OFF jumper JP3 to the O N posi-
tion and the U SB Current jumper JP2 to the 500mA
position. The USB current should increase to
452mA… 500mA. Increase the system load to
600mA. N ote that as the load current becomes
higher than the USB current, discharge current is
flow ing from the battery to the load. The output
voltage drops to just below the battery voltage 3.6V.
Adapter Charging
8. Test of operation w ith H VIN input: Connect the ad-
justable 0-50V pow er supply to the demo board
HVIN input, turn it on and slow ly increase the HVIN
voltage. W hen H VIN exceeds about 6V the U SB current drops to zero and current is draw n from 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).
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