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參數(shù)資料
| 型號： | ADP3408 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Replaced by BQ29415 : Voltage Protection for 2, 3, or 4 Cell LiIon Batteries (2nd Lev Protection) 8-SM8 -25 to 85 |
| 中文描述： | 手機電源管理系統(tǒng) |
| 文件頁數(shù)： | 15/16頁 |
| 文件大小： | 206K |
| 代理商： | ADP3408 |
REV. 0
ADP3408
–15–
Appropriate sense resistors are available from the following
vendors:
Vishay Dale
IRC
Panasonic
Charger FET Selection
The type and size of the pass transistor is determined by the
threshold voltage, input-output voltage differential, and the
charge current. The selected PMOS must satisfy the physical,
electrical and thermal design requirements.
To ensure proper operation, the minimum
V
GS
the ADP3408
can provide must be enough to turn on the FET. The available
gate drive voltage can be estimated using the following:
V
V
V
V
GS
ADAPTER MIN
GATEDR
SENSE
=
(
)
(8)
where:
V
ADAPTER(MIN)
is the minimum adapter voltage,
V
GATEDR
is the
gate drive
“
low
”
voltage, 0.5 V, and
V
SENSE
is the maximum
high current limit threshold voltage.
The difference between the adapter voltage (
V
ADPTER
) and the
final battery voltage (
V
BAT
) must exceed the voltage drop due to
the blocking diode, the sense resistor, and the ON resistance of
the FET at maximum charge current, where:
V
The
R
DS(ON)
of the FET can then be calculated.
V
I
CHR MAX
(
)
V
V
V
V
DS
ADAPTER MIN
DIODE
SENSE
BAT
=
(
)
(9)
R
DS ON
(
DS
)
=
(10)
The thermal characteristics of the FET must be considered
next. The worst-case dissipation can be determined using:
(
P
V
V
V
UVLO
I
DISS
ADAPTER MAX
DIODE
SENSE
CHR
=
)
×
(
)
(11)
It should be noted that the adapter voltage can be either
preregulated or nonregulated. In the preregulated case the
difference between the maximum and minimum adapter voltage
is probably not significant. In the unregulated case, the adapter
voltage can have a wide range specified. However, the maximum
voltage specified is usually with no load applied. So, the worst-case
power dissipation calculation will often lead to an over-specified
pass device. In either case, it is best to determine the load
characteristics of the adapter to optimize the charger design.
For example:
V
ADAPTER(MIN)
= 5.0 V
V
ADAPTER(MAX)
= 6.5 V
V
DIODE
= 0.5 V at 800 mA
V
SENSE
= 160 mV
V
GATEDR
= 0.5 V
V
GS
= 5 V
–
0.5 V
–
160 V = 4.34 V
Therefore, choose a low threshold voltage FET.
V
5
V
0 5
V
V
=
V
V
V
V
V
mV
mA
mV
R
V
I
m
P
V
V
V
UVLO
I
P
V
V
V
A
DS
ADAPT MIN
–
.
DIODE
–
.
4 2
140
800
SENSE
140
BAT
DS ON
(
DS
CHR MAX
(
DISS
ADAPT MAX
DIODE
SENSE
CHR
DISS
=
=
=
=
=
=
(
=
(
)
×
=
)
×
(
)
)
)
(
)
–
–
–
–
.
0 160
–
–
–
.
–
.
0 5
–
.
0 160
–
.
3 2
.
.
175
6 5
0 8
2 11
W
Appropriate PMOS FETs are available from the following
vendors:
Siliconix
IR
Fairchild
Charger Diode Selection
The diode, D1, shown in Figure 2, is used to prevent the battery from
discharging through the PMOS
’
body diode into the charger
’
s
internal bias circuits. Choose a diode with a current rating high
enough to handle the battery charging current and a voltage
rating greater than VBAT. The blocking diode is required for
both lithium and nickel battery types.
Printed Circuit Board Layout Considerations
Use the following general guidelines when designing printed
circuit boards:
1. Connect the battery to the VBAT, VBAT2, and VRTCIN
pins of the ADP3408. Locate the input capacitor as close to
the pins as possible.
2. VAN and VTCXO capacitors should be returned to AGND.
3. VCORE, VMEM and VSIM capacitors should be returned
to DGND.
4. Split the ground connections. Use separate traces or planes
for the analog, digital, and power grounds and tie them together
at a single point, preferably close to the battery return.
5. Run a separate trace from the BATSNS pin to the battery to
prevent voltage drop error in the MVBAT measurement.
6. Kelvin-connect the charger
’
s sense resistor by running sepa-
rate traces to the CHRIN and ISENSE pins. Make sure that the
traces are terminated as close to the resistor
’
s body as possible.
7. Use the best industry practice for thermal considerations
during the layout of the ADP3408 and charger components.
Careful use of copper area, weight, and multilayer construc-
tion all contribute to improved thermal performance.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ADP3408ARU-18 | GSM Power Management System |
| ADP3410KRU | Dual MOSFET Driver with Bootstrapping |
| ADP3410 | Dual MOSFET Driver with Bootstrapping |
| ADP3412 | Replaced by BQ29415 : Voltage Protection for 2, 3, or 4 Cell LiIon Batteries (2nd Lev Protection) 8-SM8 -25 to 85 |
| ADP3412JR | Secondary Over-Voltage Protection for 2-4 cell in series Li-Ion/Poly (4.35V) 8-SM8 -40 to 110 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADP3408ACP-1.8-RL | 制造商:Analog Devices 功能描述:GSM Power Management System 32-Pin LFCSP EP T/R |
| ADP3408ACP-1.8-RL7 | 制造商:Rochester Electronics LLC 功能描述:GSM POWER MANAGEMENT SYSTEM - Bulk |
| ADP3408ACP-2.5-RL | 制造商:Analog Devices 功能描述:GSM Power Management System 32-Pin LFCSP EP T/R |
| ADP3408ACP-2.5-RL7 | 制造商:Analog Devices 功能描述:GSM Power Management System 32-Pin LFCSP EP T/R 制造商:Rochester Electronics LLC 功能描述:MSM POWER MANAGEMENT SYSTEM - Bulk |
| ADP3408ARU-1.8 | 制造商:Analog Devices 功能描述:BATTERY MANAGEMENT, 28 Pin, Plastic, TSSOP |
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