Linear Technology DC1210A User manual

LTC4090
1
DESCRIPTION
Demonstration circuit DC1210A is high voltage sw itching
buck regulator, USB Pow erpath controller an Li-Ion bat-
tery charger. It is base on the LTC4090 an provi es
the follow ing functions:
2A buck regulator w ith 6-38V (60V max) input range an
w ith output voltage tracking battery voltage, full feature
battery charger w ith 4.2V float, USB pow er manager that
ensures compliance w ith the USB pow er specification
an a pow er path manager for the battery.
PERF ORM A NCE SU M M A RY Specifications are at TA = 25°C
SYM BOL PARAM ETER CON DITIONS M IN TYP M A UNITS
V
IN
Input Supply Range - USB 4.35 5.5
V
V
HVIN
Input Supply Range - HVIN (W ithstan s up to 60V w ithout amage) 6 60
V
V
OVLO
HVIN Overvoltage Lockout Threshol 38 41.5 45
V
Battery Charger
I
CHG
Charging current V
HVIN
= 12V, V
BAT
= 3.6V , R4 = 71.5k Ω 650 700 750 m
A
V
FLOAT
V
BAT
Regulate Output Voltage I
BAT
= 2mA 4.165 4.200 4.235
V
I
TRKL
Trickle Charge Current V
BAT
= 2V 49 70 84 m
A
∆ V
RECHRG
Recharge threshol Threshol Voltage Relative to V
FLOAT
-65 -100 -135 m
V
Input Current
I
LIM
Input current 100mA mo e HPW R = 0V, R3 = 2.10k Ω 86 93 105 m
A
I
LIM
Input Current 500mA mo e HPW R = 5V, R3 = 2.10k Ω 452 476 500
mA
I
IN(SUSP)
Suspen M o e Input Current SUSP = 5V 50 100
µA
OPERA TING PRINCIPL ES
Demo boar DC1210A is base on the LTC4090. This
chip manages the pow er supplies that w oul be typical
for a USB pow ere evice. Pow er is input from either the
USB cable or from a high voltage ( 6V-38V) HVIN input
to an interme iate voltage bus.
The interme iate voltage bus is pow ere from USB or
HVIN w hen available, an from the battery via an i eal
io e. The battery charger is a CC/CV timer terminate
type capable of charge currents up to 1.5A
The HVIN input has overvoltage protection to 60V. The
2A buck regulator connecte to HVIN operates at 800kHz
an its output voltage is regulate in the range 3.45V to
4.6V, tracking the battery voltage an typically 0.3V
higher to allow most efficient charging.
DEMO
C IR C U IT
DC
1 2 1 0
A
Q u ic k S ta rt G u id e
L T C 4 0 9 0
U S B P w e r Ma n a g e r w ith
2 A
H ig h V lta g e B u c k R e g u la t r
B u c k
I n / P ly m e r C h a rg e r

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 USB input test
1 USB cable w ith a M ini-B connector at one en an tw o banana plugs at the other en
1 DC Supply 0-5V 3A
1 Pow er Resistor 2ohm 10W
1 A justable loa 0-2A
G ETTING STA RTED
Refer to Figure 1 for proper measurement equipment
setup an follow the proce ure below :
1. W ith pow er off, connect the input pow er supplies,
meters an output loa as show n in Figure 1. For
the USB input, use an a justable 0-5V 0.5A pow er
supply an a cable w ith a U SB M ini-B connector that
plugs into J1. For the H VIN input , use a 0-50V 3A
a justable pow er supply. For simulating the battery,
use a 0-5V a justable pow er supply that can eliver
at least 3A, in parallel w ith a 2 Ω 10 W pow er resis-
tor . Attach a 0-2A a justable loa to the System
Output.
2. Check that the jumpers are in their efault 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 loa at zero.
Disconnect the HVIN pow er supply from the HVIN
input on the emo boar or turn it off. Set the USB
ON/OFF jumper JP3 in the ON position. Increase the
USB input voltage. The charger shoul activate an
green LED D3 w ill illuminate to in icate charge. Set
the USB voltage to 5.0V. The battery w ill now be in
trickle charge mo e an the charge current shoul
be in the range 49mA… 84mA.
4. Test of normal charge current: Slow ly increase the
battery voltage to 3.6V an 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 of input current limit in 100mA mo e: Place the
USB Current jumper JP2 in the 100mA position an
note that USB current falls to 86mA… 105mA.
6. Test of USB current in Suspen M o e. Set the USB
ON/OFF jumper JP3 in the OFF position an check
that the USB current rops to less than 90uA.
7. Return the USB O N/OFF jumper JP3 to the ON posi-
tion an the USB Current jumper JP2 to the 500mA
position. The U SB current shoul increase to
452mA… 500mA. Increase the system loa to
600mA. Note that as the loa current becomes
higher than the USB current, ischarge current is
flow ing from the battery to the loa . The output
voltage rops to just below the battery voltage 3.6V.
Adapter Charging
8. Test of operation w ith HVIN input: Connect the a -
justable 0-50V pow er supply to the emo boar
HVIN input, turn it on an slow ly increase the HVIN
voltage. W hen HVIN excee s about 6V the USB cur-
rent rops to zero an current is raw n from HVIN.
The re LED D3 w ill light up to in icate 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 an the output voltage has
increase to about 3.9V. The buck regulator on the
HVIN input is now both charging the battery an
pow ering the loa . Increase the system loa to 1.3A
an check that the battery charge current oes not
rop. (The buck regulator is elivering 1.3A + 0.7A =
2A current).

LTC4090
3
9. Test of the HVIN input overvoltage protection: In-
crease the HVIN input voltage slow ly an note that
as the voltage excee s 38V… 45V the input current
w ill rop to zero in icating that the buck regulator
shut ow n ue to overvoltage. The System Loa is
now pow ere from the battery (an from USB if
available). Decrease the HVIN voltage an observe
that the buckregulator w ill resume normal operation.
10. Increase the battery voltage an note that the
charge current falls to zero w hen the voltage ex-
cee s 4.167V… 4.215V.
Figure 1. Proper M easurement Equipment Setup

LTC4090
4

Mouser Electronics
Authorized Distributor
Click to View Pricing, Inventory, Delivery & Lifecycle Information:
Analog Devices Inc.:
DC1210A