Texas Instruments bq24072RGTR, User Manual

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Performance Specification Summary
The two potential sources to power the system (V
OUT
) are the input source and the battery (adapter or
USB port). The IC is designed to power the system continuously. The battery, in most cases, is the last
line of backup. If the adapter/USB input is not available (or disabled), the battery connects to the system.
In thermal regulation condition (T
J
= 125°C not a first-choice design mode of operation), the charge current
is reduced to the battery, and the system still gets its power from the input. The battery supplement is
available in thermal regulation if the V
OUT
falls to V
BAT
. In thermal cutoff (~155°C), the input sources are
disconnected, but the internal battery FET connects the battery to V
OUT
.
3 Performance Specification Summary
Table 2 summarizes the performance specifications of the EVM.
Table 2. Performance Specification Summary for bq24072/3/4/5/9(T) and bq24230/2 EVMs
SPECIFICATION TEST CONDITIONS MIN TYP MAX UNITS
Input dc Voltage, V
I(AC)
4.75 5 6.5 Volts
Battery Charge Current, I
O(CHG)
1 1.5 Amperes
Power Dissipation, bq24072/3/4/5/9(T) and bq24230/2 Pdiss = (Vin-Vout)Iout +(Vin-Vbat)Ibat See
(1)
Watts
IC, 1 Cell
(1)
The HPA073 (bq24072/3/4/5/9(T) and bq24230/2) thermal design is optimized (8
+
vias, 0.031-inch PCB, 2-oz. copper) to give
q
JA
~ 27°C/W.
3.1 Performance Recommendations
This IC is a linear battery charger and also powers the system from the input via the linear regulator
output. The key here is that this is a linear device that is most efficient when the input voltage is not too far
above the battery voltage (Vin = 4.75 V to 5.5 V). Too low of input voltage (less than the OUT voltage plus
the dropout voltage) results in degraded performance. Excessive input voltage (>5.5 V) results in excess
power dissipation and reduced performance via thermal regulation. The IC is rated to 28 V, and will not be
damaged with Vin voltages less than this, but any Vin voltage over the overvoltage protection (OVP)
threshold disables the IC. Thus, the recommended operating range for maximum performance is between
4.75 V and 5.5 V, with a preference toward the lower values.
4 Test Summary
This section covers the setup and tests performed in evaluating the EVM.
4.1 Equipment
• Power supply (+5.25 ±0.25 Vdc), current limit set to 2 A ±0.2 A
• Three Fluke 75 DMMs (equivalent or better)
• Oscilloscope, Model TDS220 (equivalent or better)
4.2 Equipment and EVM Setup
• Preset P/S#1 to 5.25 V ±0.25 V, 2 A ±0.25-A current limit, turn off and connect to J1-IN/GND ( + to IN
and – to GND)
• Connect a 10- Ω , 10-W resistor to J2-OUT/VSS
• Connect a fully discharged (Vbat <2.8 V) Battery to J3-BAT+/VSS (+ to BAT+ and – to VSS).
• Apply the jumpers as per Table 3 .
• For the bq2407xEVM, adjust the potentiometers as follows (measure resistance from TP# to VSS):
– R8 (ILIM-TP12) = 750
Ω
(743 to 757); R11 (ISET-TP16) = 1 k
Ω
(0.98 k
Ω
to 1.02 k
Ω
) and R16
(TS-TP1) = 7.5 k Ω (7.3 k Ω to 7.7 k Ω ); and for ’74 (-003): R10 (ITERM-TP15) = 3 k Ω (2.98 k Ω to
3.02 k
Ω
).
• For the bq2423xEVM, adjust the potentiometers as follows (measure resistance from TP# to VSS):
– R8 (ILIM-TP12) = 750
Ω
(743 to 757); R11 (ISET-TP16) = 2.96 k
Ω
(2.93 k
Ω
to 2.99 k
Ω
) and R16
(TS-TP1) = 7.5 k Ω (7.3 k Ω to 7.7 k Ω ); and for ’74 (-006): R10 (ITERM-TP15) = 3 k Ω (2.98 k Ω to
3.02 k
Ω
).
3 SLVU274C – November 2008 – Revised May 2010 bq24072/3/4/5/9(T) and bq24230/2 1.5-A Single-Chip Li-Ion —and Li-Polymer
Charge Management IC EVM
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