EUP8054/8054X Standalone Linear Li

EUP8054/8054X Standalone Linear Li
EUP8054/8054X
Standalone Linear Li-Ion Battery Charger
With Thermal Regulation in ThinSOT
DESCRIPTION
FEATURES
The EUP8054 is a complete constant-current/constantvoltage linear charger for single cell lithium-ion batteries.
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Programmable Charge Current Up to 800mA
No MOSFET, Sense Resistor or Blocking Diode
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Required
Complete Linear Charger in ThinSOT Package for
Single Cell Lithium-ion Batteries
Its ThinSOT package and low external component count
make the EUP8054 ideally suited for portable applications.
Furthermore, the EUP8054 is specifically designed to
work within USB power specifications.
No external sense resistor is needed, and no blocking
diode is required due to the internal MOSFET architecture.
Thermal feedback regulates the charge current to limit the
die temperature during high power operation or high
ambient temperature. The charge voltage is fixed at 4.2V,
and the charge current can be programmed externally with
a single resistor. The EUP8054 automatically terminates
the charge cycle when the charge current drops to 1/10th
the programmed value after the final float voltage is
reached.
When the input supply (wall adapter or USB supply) is
removed, the EUP8054 automatically enters a low current
state, dropping the battery drain current to less than 2µA.
The EUP8054 can be put into shutdown mode, reducing
the supply current to 25µA.
Other features include charge current monitor,
undervoltage lockout, automatic recharge and a status pin
to indicate charge termination and the presence of an input
voltage.
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Constant-Current/Constant-Voltage Operation with
Thermal Regulation to Maximize Charge Rate
Without Risk of Overheating
Charges Single Cell Li-Ion Batteries Directly from
USB Port
Preset 4.2V Charge Voltage with ± 1% Accuracy
Charge Current Monitor Output for Gas Gauging
Automatic Recharge
Charge Status Output Pin
C/10 Charge Termination
25µA Supply Current in Shutdown
2.9V Trickle Charge Threshold (EUP8054)
Available Without Trickle Charge (EUP8054X)
Soft-Start Limits Inrush Current
Available in TSOT-25, TDFN-6(3mm*3mm)
Package
RoHS Compliant and 100% Lead (Pb)-Free
APPLICATIONS
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DS8054
Ver1.1
Jan. 2007
1
Cellular Telephones/ PDAs/ MP3 Players
Charging Docks and CradIes
Bluetooth Applications
EUP8054/8054X
Typical Application Circuit
Figure 1. 600mA Single Cell Li-ion Charger
Figure 2. USB/Wall Adapter Power Li-Ion Charger
Figure 3. Full Featured Single Cell Li-Ion Charger
Figure 4. 800mA Li-Ion Charger with External
Power Dissipation
Figure 5. Basic Li-Ion Charger with Reverse
Polarity Input Protection
DS8054
Ver1.1
Jan. 2007
2
EUP8054/8054X
Pin Configurations
Package Type
Pin
Configurations
TSOT-25
TDFN-6
Pin Description
PIN
TSOT-25
TDFN6
CHRG
1
1
Open-Drain Status Output
GND
2
2
Ground
BAT
3
6
Charge Current Output
VCC
4
4
Positive Input Supply Voltage
PROG
5
3
Charge Current Program, Charge Current Monitor and Shutdown Pin.
5
No connection
N/C
DESCRIPTION
Pin Functions
CHRG :Open-Drain Charge Status Output. When the battery is charging, the CHRG pin is pulled low by an
internal N-channel MOSFET. When the charge cycle is completed, a weak pull-down of approximately 12µA is
connected to the CHRG pin, indicating a “AC present” condition. When the EUP8054 detects an undervoltage
lockout condition, CHRG is forced high impedance.
GND : Ground.
BAT : Charge Current Output. Provides charge current to the battery and regulates the final float voltage to 4.2V.
An internal precision resistor divider from this pin sets the float voltage which is disconnected in shutdown
mode.
VCC : Positive Input Supply Voltage. Provides power to the charger. VCC can range from 4.35V to 6.5V and
should be bypassed with at least a 1µF capacitor. When VCC drops to within 30mV of the BAT pin voltage, the
EUP8054 enters shutdown mode, dropping IBAT to less than 2µA.
DS8054
Ver1.1
Jan. 2007
3
EUP8054/8054X
Pin Functions (continue)
PROG: Charge Current Program, Charge Current Monitor and Shutdown Pin. The charge current is programmed
by connecting a 1% resistor, RPROG, to ground. When charging in constant-current mode, this pin servos to 1V. In
all modes, the voltage on this pin can be used to measure the charge current using the following formula:
(
)
I BAT = VPROG / R PROG • 1000
The PROG pin can also be used to shutdown the charger. Disconnecting the program resistor from ground
allows a 3µA current to pull the PROG pin high. When it reaches the 1.94V shutdown threshold voltage, the
charger enters shutdown mode, charging stops and the input supply current drops to 25µA. This pin is also
clamped to approximately 2.4V. Driving this pin to voltages beyond the clamp voltage will draw currents as high
as1.5mA. Reconnecting RPROG to ground will return the charger to normal operation.
N/C: No connection.
Ordering Information
Order Number
Package Type
Marking
Operating Temperature range
EUP8054OIR1
TSOT-25
UNxx
-20 °C to 70°C
EUP8054XOIR1
TSOT-25
UXxx
-20 °C to 70°C
EUP8054RIR1
TDFN-6
xxxx
8054N
-20 °C to 70°C
EUP8054/X
□
□ □ □
Lead Free Code
1: Lead Free 0: Lead
Packing
R: Tape& Reel
Operating temperature range
I: Industry Standard
Package Type
O: TSOT
R:TDFN
DS8054
Ver1.1
Jan. 2007
4
EUP8054/8054X
Absolute Maximum Ratings
„
Input Supply voltage, (Vcc) ------------------------------------------------------------------------- -0.3 to +6.5V
PROG ------------------------------------------------------------------------------------------- -0.3V to VCC +0.3V
BAT ----------------------------------------------------------------------------------------------------- -0.3 to +6.5V
„
CHRG --------------------------------------------------------------------------------------------------
„
BAT Short-Circuit Duration -------------------------------------------------------------------------- Continuous
BAT Pin Current --------------------------------------------------------------------------------------------- 800mA
PROG Pin Current ------------------------------------------------------------------------------------------- 800µA
Maximum Junction Temperature, ------------------------------------------------------------------------ 125°C
Operating Ambient Temperature Range (Note 2) ----------------------------------------------- -40°C to 85°C
Storage Temperature Range ----------------------------------------------------------------------- -65°C to 125°C
Lead Temperature (soldering, 10s) ----------------------------------------------------------------------- 300°C
„
„
„
„
„
„
„
„
-0.3 to +6.5V
Electrical Characteristics over Recommended Operating Free-Air Temperature Range
Otherwise specifications are at TA=25℃. VCC=5V, unless otherwise noted.
Symbol
VCC
ICC
VFLOAT
Parameter
Conditions
4.35
Input Supply Voltage
Input Supply Current
Regulated Output (Float) Voltage
EUP8054
Min. Typ. Max.
Charge Mode (Note 4),RPROG = 10k
Standby Mode (Charge Terminated)
Shutdown Mode (RPROG Not
Connected,
VCC < VBAT, or VCC < VUV)
0℃ ≤ TA ≤ 85℃, IBAT = 40mA
Unit
350
200
25
6.5
2000
500
50
V
µA
4.158
100
475
0
4.2
110
510
-2.5
±1
±1
4.242
120
545
-6
±2
±2
V
mA
mA
µA
µA
µA
BAT Pin Current
RPROG = 10k, Current Mode
RPROG = 2k, Current Mode
Standby Mode, VBAT = 4.2V
Shutdown Mode (RPROG Not
Connected)
Sleep Mode, VCC = 0V
ITRIKL
Trickle Charge Current
VBAT < VTRIKL, RPROG = 2k (Note 5)
20
50
70
mA
VTRIKL
Trickle Charge Threshold Voltage
RPROG = 10k, VBAT Rising (Note 5)
2.8
2.9
3.0
V
VTRHYS
Trickle Charge Hysteresis Voltage
RPROG = 10k (Note 5)
60
80
110
mV
IBAT
VCC Undervoltage Lockout Threshold From VCC Low to High
3.55
3.7
3.85
V
VUVHYS
VCC Undervoltage Lockout Hysteresis
150
200
300
mV
VMSD
Manual Shutdown Threshold Voltage
PROG Pin Rising
VCC – VBAT Lockout Threshold
Voltage
ITERM
C/10 Termination Current Threshold
VPROG
PROG Pin Voltage
VCC from Low to High
VCC from High to Low
RPROG = 10k (Note 6)
RPROG = 2k
RPROG = 10k, Current Mode
1.94
100
30
0.10
0.10
1.03
2.05
140
50
0.115
0.115
1.10
V
VASD
1.85
70
5
0.085
0.085
0.96
7
12
20
VUV
I CHRG
DS8054
CHRG Pin Weak Pull-Down
Current
Ver1.1
Jan. 2007
V CHRG = 5V
5
mV
mA/mA
V
µA
EUP8054/8054X
Electrical Characteristics Over Recommended Operating Free-Air Temperature Range
Otherwise specifications are at TA=25℃. VCC=5V, unless otherwise noted.
Symbol
V CHRG
ΔVRECHRG
TLIM
RON
tSS
Parameter
Conditions
CHRG Pin Output Low Voltage
I CHRG = 5mA
Recharge Battery Threshold Voltage
VFLOAT-VRECHRG
EUP8054
Min. Typ. Max.
Unit
0.35
0.6
V
150
200
mV
100
Junction Temperature in Constant
Temperature Mode
Power FET “ON” Resistance
(Between VCC and BAT)
Soft-Start Time
tRECHARGE Recharge Comparator Filter Time
tTERM
Termination Comparator Filter Time
IPROG
PROG Pin Pull-Up Current
IBAT = 0 to IBAT =1000V/RPROG
120
℃
600
mΩ
100
µs
VBAT High to Low
0.75
2
4.5
ms
IBAT Falling Below ICHG/10
400
1000
2500
µs
3
µA
Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired.
Note 2: The EUP8054 are guaranteed to meet performance specifications from 0℃ to 70℃. Specifications over the -40℃ to 85℃
operating temperature range are assured by design, characterization and correlation with statistical process controls.
Note 3: See Thermal Considerations.
Note 4: Supply current includes PROG pin current (approximately 100µA) but does not include any current delivered to the battery
through the BAT pin (approximately 100mA).
Note 5: This parameter is not applicable to the EUP8054X.
Note 6: I TERM is expressed as a fraction of measured full charge current with indicated PROG resistor.
DS8054
Ver1.1
Jan. 2007
6
EUP8054/8054X
Typical Operating Characteristics
DS8054
Ver1.1
Jan. 2007
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EUP8054/8054X
DS8054
Ver1.1
Jan. 2007
8
EUP8054/8054X
DS8054
Ver1.1
Jan. 2007
9
EUP8054/8054X
Block Diagram
Figure 6. Block Diagram
DS8054
Ver1.1
Jan. 2007
10
EUP8054/8054X
Operation
Charge Termination
The EUP8054 is a single cell lithium-ion battery charger
using a constant-current/constant-voltage algorithm. It
can deliver up to 800mA of charge current (using a good
thermal PCB layout) with a final float voltage accuracy
of ± 1%. The EUP8054 includes an internal P-channel
power MOSFET and thermal regulation circuitry. No
blocking diode or external current sense resistor is
required; thus, the basic charger circuit requires only two
external components. Furthermore, the EUP8054 is
capable of operating from a USB power source.
A charge cycle is terminated when the charge current
falls to 1/10th the programmed value after the final float
voltage is reached. This condition is detected by using an
internal, filtered comparator to monitor the PROG pin.
When the PROG pin voltage falls below 100mV for
longer than tTERM (typically 1ms), charging is terminated.
The charge current is latched off and the EUP8054 enters
standby mode, where the input supply current drops to
200µA.
When charging, transient loads on the BAT pin can cause
the PROG pin to fall below 100mV for short periods of
time before the DC charge current has dropped to 1/10th
the programmed value. The 1ms filter time (tTERM) on the
termination comparator ensures that transient loads of
this nature do not result in premature charge cycle termination. Once the average charge current drops below
1/10th the programmed value, the EUP8054 terminates
the charge cycle and ceases to provide any current
through the BAT pin. In this state, all loads on the BAT
pin must be supplied by the battery.
The EUP8054 constantly monitors the BAT pin voltage
in standby mode. If this voltage drops below the 4.05V
recharge threshold (VRECHRG), another charge cycle
begins and current is once again supplied to the battery.
To manually restart a charge cycle when in standby mode,
the input voltage must be removed and reapplied, or the
charger must be shut down and restarted using the PROG
pin. Figure 7 shows the state diagram of a typical charge
cycle.
Normal Charge Cycle
A charge cycle begins when the voltage at the VCC pin
rises above the UVLO threshold level and a 1% program
resistor is connected from the PROG pin to ground or
when a battery is connected to the charger output. If the
BAT pin is less than 2.9V, the charger enters trickle
charge mode. In this mode, the EUP8054 supplies
approximately 1/10 the programmed charge current to
bring the battery voltage up to a safe level for full current
charging. (Note: The EUP8054X does not include this
trickle charge feature).
When the BAT pin voltage rises above 2.9V, the charger
enters constant-current mode, where the programmed
charge current is supplied to the battery. When the BAT
pin approaches the final float voltage (4.2V), the
EUP8054 enters constant-voltage mode and the charge
current begins to decrease. When the charge current
drops to 1/10 of the programmed value, the charge cycle
ends.
Programming Charge Current
The charge current is programmed using a single resistor
from the PROG pin to ground. The battery charge current
is 1000 times the current out of the PROG pin. The
program resistor and the charge current are calculated
using the following equations:
R PROG =
1000V
1000V
, I CHG =
I CHG
R PROG
The charge current out of the BAT pin can be determined
at any time by monitoring the PROG pin voltage using
the following equation:
I BAT =
DS8054
VPROG
• 1000
R PROG
Ver1.1
Jan. 2007
11
Charge Status Indicator ( CHRG )
The charge status output has three different states: strong
pull-down(~10mA), weak pull-down (~12µA) and high
impedance. The strong pull-down state indicates that the
EUP8054 is in a charge cycle. Once the charge cycle has
terminated , the pin state is determined by undervoltage
lockout conditions. A weak pull-down indicates that VCC
meets the UVLO conditions and the EUP8054 is ready to
charge. High impedance indicates that the EUP8054 is in
undervoltage lockout mode: either VCC is less than
100mV above the BAT pin voltage or insufficient voltage
is applied to the VCC pin. A microprocessor can be used
to distinguish between these three states –this method is
discussed in the Applications Information section.
EUP8054/8054X
Thermal Limiting
An internal thermal feedback loop reduces the
programmed charge current if the die temperature
attempts to rise above a preset value of approximately
120℃. This feature protects the EUP8054 from excessive
temperature and allows the user to push the limits of the
power handling capability of a given circuit board
without risk of damaging the EUP8054. The charge
current can be set according to typical (not worst-case)
ambient temperature with the assurance that the charger
will automatically reduce the current in worst-case
conditions. ThinSOT power considerations are discussed
further in the Applications Information section.
Undervoltage Lockout (UVLO)
An internal undervoltage lockout circuit monitors the
input voltage and keeps the charger in shutdown mode
until VCC rises above the undervoltage lockout
threshold .The UVLO circuit has a built-in hysteresis of
200mV. Furthermore, to protect against reverse current in
the power MOSFET, the UVLO circuit keeps the charger
in shutdown mode if VCC falls to within 30mV of the
battery voltage. If the UVLO comparator is tripped, the
charger will not come out of shutdown mode until VCC
rises 100mV above the battery voltage.
Manual Shutdown
At any point in the charge cycle, the EUP8054 can be put
into shutdown mode by removing RPROG thus floating the
PROG pin. This reduces the battery drain current to less
than 2µA and the supply current to less than 50µA. A new
charge cycle can be initiated by reconnecting the program
resistor.
In manual shutdown, the CHRG pin is in a weak
pull-down state as long as VCC is high enough to exceed
the UVLO conditions. The CHRG pin is in a high
impedance state if the EUP8054 is in undervoltage
lockout mode: either VCC is within 100mV of the BAT
pin voltage or insufficient voltage is applied to the VCC
pin.
Automatic Recharge
Once the charge cycle is terminated, the EUP8054
continuously monitors the voltage on the BAT pin using a
comparator with a 2ms filter time (tRECHARGE). A charge
cycle restarts when the battery voltage falls below 4.05V
(which corresponds to approximately 80% to 90% battery
capacity). This ensures that the battery is kept at or near a
fully charged condition and eliminates the need for
periodic charge cycle initiations. CHRG output enters a
strong pull-down state during recharge cycles.
DS8054
Ver1.1
Jan. 2007
12
Figure 7. State Diagram of a Typical Charge Cycle
EUP8054/8054X
Application Information
Stability Considerations
The constant-voltage mode feedback loop is stable
without an output capacitor provided a battery is
connected to the charger output. With no battery present,
an output capacitor is recommended to reduce ripple
voltage. When using high value, low ESR ceramic
capacitors, it is recommended to add a 1Ω resistor in
series with the capacitor. No series resistor is needed if
tantalum capacitors are used.
In constant-current mode, the PROG pin is in the
feedback loop, not the battery. The constant-current mode
stability is affected by the impedance at the PROG pin.
With no additional capacitance on the PROG pin, the
charger is stable with program resistor values as high as
20k. However, additional capacitance on this node
reduces the maximum allowed program resistor. The pole
frequency at the PROG pin should be kept above 100kHz.
Therefore, if the PROG pin is loaded with a capacitance,
CPROG, the following equation can be used to calculate
the maximum resistance value for RPROG:
R PROG ≤
1
5
2π • 10 • C
PROG
Average, rather than instantaneous, charge current may
be of interest to the user. For example, if a switching
power supply operating in low current mode is connected
in parallel with the battery, the average current being
pulled out of the BAT pin is typically of more interest
than the instantaneous current pulses. In such a case, a
simple RC filter can be used on the PROG pin to measure
the average battery current as shown in Figure 8. A 10k
resistor has been added between the PROG pin and the
filter capacitor to ensure stability.
Power Dissipation
The conditions that cause the EUP8054 to reduce charge
current through thermal feedback can be approximated
by considering the power dissipated in the IC. Nearly all
of this power dissipation is generated by the internal
MOSFET—this is calculated to be approximately:
PD=(VCC-VBAT) • IBAT
where PD is the power dissipated, VCC is the input supply
voltage, VBAT is the battery voltage and IBAT is the charge
current. The approximate ambient temperature at which
the thermal feedback begins to protect the IC is:
TA=120℃-PDθJA
TA=120℃-(VCC-VBAT) • IBAT • θJA
Example: An EUP8054 operating from a 5V USB supply
is programmed to supply 400mA full-scale current to a
discharged Li-Ion battery with a voltage of 3.75V.
Assuming θJA is 150℃/W (see Board Layout
Considerations ), the ambient temperature at which the
EUP8054 will begin to reduce the charge current is
approximately:
TA=120℃-(5V-3.75V) • (400mA) • 150℃/W
TA=120℃-0.5W • 150℃/W=120℃-75℃
TA=45℃
The EUP8054 can be used above 45℃ ambient, but the
charge current will be reduced from 400mA. The
approximate current at a given ambient temperature can
be approximated by:
I BAT =
120°C −T A
(VCC − VBAT ) • θ JA
Using the previous example with an ambient temperature
of 60℃, the charge current will be reduced to
approximately:
120°C − 60°C
60°C
=
I BAT =
(5V − 3.75V ) • 150°C / W 187.5°C / A
I BAT = 320mA
Figure 8. Isolating Capacitive Load on PROG Pin
and Filtering
DS8054
Ver1.1
Jan. 2007
13
Moreover, when thermal feedback reduces the charge
current, the voltage at the PROG pin is also reduced
proportionally as discussed in the Operation section.
It is important to remember that EUP8054 applications
do not need to be designed for worst-case thermal
conditions since the IC will automatically reduce power
dissipation when the junction temperature reaches
approximately 120℃.
EUP8054/8054X
Thermal Considerations
Because of the small size of the ThinSOT package, it is
very important to use a good thermal PC board layout to
maximize the available charge current. The thermal path
for the heat generated by the IC is from the die to the
copper lead frame, through the package leads, (especially
the ground lead) to the PC board copper. The PC board
copper is the heat sink. The footprint copper pads should
be as wide as possible and expand out to larger copper
areas to spread and dissipate the heat to the surrounding
ambient. Feedthrough vias to inner or backside copper
layers are also useful in improving the overall thermal
performance of the charger .Other heat sources on the
board, not related to the charger , must also be considered
when designing a PC board layout because they will
affect overall temperature rise and the maximum charge
current.
Reducing the voltage drop across the internal MOSFET
can significantly decrease the power dissipation in the IC.
This has the effect of increasing the current delivered to
the battery during thermal regulation. One method is by
dissipating some of the power through an external
component, such as a resistor or diode.
Example: An EUP8054 operating from a 5V wall adapter
is programmed to supply 800mA full-scale current to a
discharged Li-Ion battery with a voltage of 3.75V.
Assuming θJA is 125℃/W, the approximate charge
current at an ambient temperature of 25℃ is:
120°C − 25°C
(5V − 3.75V ) • 125°C / W
= 608mA
By dropping voltage across a resistor in series with a 5V
wall adapter (shown in Figure 9), the on-chip power
dissipation can be decreased, thus increasing the
thermally regulated charge current
I BAT =
DS8054
120°C − 25°C
(VS − I BATR CC − VBAT ) • θJA
Ver1.1
Jan. 2007
Solving for IBAT using the quadratic formaula2
I BAT =
Increasing Thermal Regulation Current
I BAT =
Figure 9. A Circuit to Maximize Thermal Mode
Charge Current
14
°C − TA )
(VS − VBAT ) − (VS − VBAT )2 4R CC (120
θ
JA
2R CC
Using RCC = 0.25Ω, VS = 5V, VBAT = 3.75V, TA = 25℃
and θJA = 125℃/W we can calculate the thermally
regulated charge current to be:
I BAT = 708.4mA
While this application delivers more energy to the battery
and reduces charge time in thermal mode, it may actually
lengthen charge time in voltage mode if VCC becomes
low enough to put the EUP8054 into dropout.
This technique works best when RCC values are
minimized to keep component size small and avoid
dropout. Remember to choose a resistor with adequate
power handling capability.
VCC Bypass Capacitor
Many types of capacitors can be used for input bypassing,
however, caution must be exercised when using
multilayer ceramic capacitors. Because of the
self-resonant and high Q characteristics of some types of
ceramic capacitors, high voltage transients can be
generated under some start-up conditions, such as
connecting the charger input to a live power
source .Adding a 1.5Ω resistor in series with an X5R
ceramic capacitor will minimize start-up voltage
transients.
EUP8054/8054X
Charge Current Soft-Start
The EUP8054 includes a soft-start circuit to minimize the
inrush current at the start of a charge cycle. When a
charge cycle is initiated, the charge current ramps from
zero to the full-scale current over a period of
approximately 100µs. This has the effect of minimizing
the transient current load on the power supply during
start-up.
CHRG Status Output Pin
The CHRG pin can provide an indication that the input
voltage is greater than the undervoltage lockout threshold
level. A weak pull-down current of approximately 12µA
indicates that sufficient voltage is applied to VCC to begin
charging. When a discharged battery is connected to the
charger, the constant current portion of the charge cycle
begins and the CHRG pin pulls to ground. The
CHRG pin can sink up to 10mA to drive an LED that
indicates that a charge cycle is in progress.
When the battery is nearing full charge, the charger
enters the constant-voltage portion of the charge cycle
and the charge current begins to drop. When the charge
current drops below 1/10 of the programmed current, the
charge cycle ends and the strong pull-down is replaced
by the 12µA pull-down, indicating that the charge cycle
has ended. If the input voltage is removed or drops below
the undervoltage lockout threshold, the CHRG pin
becomes high impedance. Figure 10 shows that by using
two different value pull-up resistors, a microprocessor
can detect all three states from this pin.
2k pull-up resistor. To determine if there is a weak
pull-down current, the OUT pin should be forced to a
high impedance state. The weak current source will pull
the IN pin low through the 800k resistor; if CHRG is
high impedance, the IN pin will be pulled high,
indicating that the part is in a UVLO state.
Reverse Polarity Input Voltage Protection
In some applications, protection from reverse polarity
voltage on VCC is desired .If the supply voltage is high
enough, a series blocking diode can be used. In other
cases, where the voltage drop must be kept low a
P-channel MOSFET can be used (as shown in Figure
11.)
Figure 11. Low Loss Input Reverse Polarity
Protection
USB and Wall Adapter Power
The EUP8054 allows charging from both a wall adapter
and a USB port. Figure 12 shows an example of how to
combine wall adapter and USB power inputs. A
P-channel MOSFET, MP1,is used to prevent back
conducting into the USB port when a wall adapter is
present and a Schottky diode, D1, is used to prevent USB
power loss through the 1k pull-down resistor.
Typically a wall adapter can supply more current than the
500mA-limited USB port. Therefore, an N-channel
MOSFET, MN1, and extra 10k program resistor are used
to increase the charge current to 600mA when the wall
adapter is present.
Figure 10. Using a Microprocessor to Determine
CHRG State
To detect when the EUP8054 is in charge mode, force the
digital output pin (OUT) high and measure the voltage at
the CHRG pin. The N-channel MOSFET will pull the
pin voltage low even with the 2k pull-up resistor. Once
the charge cycle terminates, the N-channel MOSFET is
turned off and a 12µA current source is connected to the
CHRG pin. The IN pin will then be pulled high by the
DS8054
Ver1.1
Jan. 2007
15
Figure 12. Combining Wall Adapter and USB Power
EUP8054/8054X
Packaging Information
TSOT-25
SYMBOLS
A
A1
D
E1
E
L
b
e
DS8054
Ver1.1
Jan. 2007
MILLIMETERS
MIN.
MAX.
1.00
0.00
0.10
2.90
1.60
2.60
3.00
0.30
0.60
0.30
0.56
0.95
16
INCHES
MIN.
0.000
MAX.
0.039
0.004
0.114
0.063
0.102
0.012
0.012
0.118
0.024
0.022
0.037
EUP8054/8054X
Packaging Information
TDFN-6
SYMBOLS
A
A1
b
D
D1
E
E1
e
L
DS8054
Ver1.1
Jan. 2007
MILLIMETERS
MIN.
MAX.
0.70
0.90
0.00
0.05
0.30
0.50
2.85
3.15
2.30
2.85
3.15
1.50
0.95
0.38
0.58
17
INCHES
MIN.
0.028
0.000
0.012
0.112
MAX.
0.035
0.002
0.020
0.124
0.090
0.112
0.124
0.059
0.037
0.015
0.023
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