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參數(shù)資料
| 型號(hào)： | MAX1909ETI |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 電源管理 |
| 英文描述： | Multichemistry Battery Charger with Automatic System Power Selector |
| 中文描述： | 2-CHANNEL POWER SUPPLY SUPPORT CKT, QCC28 |
| 封裝： | 5 X 5 MM, 0.80 MM HEIGHT, MO-220-WHHD-1, TQFN-28 |
| 文件頁數(shù)： | 25/29頁 |
| 文件大?。?/td> | 551K |
| 代理商： | MAX1909ETI |
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M
Multichemistry Battery Charger with Automatic
System Power Selector
______________________________________________________________________________________
25
Design Procedure
Table 2 lists the recommended components and refers
to the circuit of Figure 2. The following sections
describe how to select these components.
MOSFET Selection
MOSFETs P2 and P3 (Figure 1) provide power to the
system load when the AC adapter is inserted. These
devices may have modest switching speeds, but must
be able to deliver the maximum input current as set by
RS1. As always, care should be taken not to exceed
the device
’
s maximum voltage ratings or the maximum
operating temperature.
The P-channel/N-channel MOSFETs (P1, N1) are the
switching devices for the buck controller. The guide-
lines for these devices focus on the challenge of
obtaining high load-current capability when using high-
voltage (>20V) AC adapters. Low-current applications
usually require less attention. The high-side MOSFET
(P1) must be able to dissipate the resistive losses plus
the switching losses at both V
DCIN(MIN)
and
V
DCIN(MAX)
.
Ideally, the losses at V
DCIN(MIN)
should be roughly
equal to losses at V
DCIN(MAX)
, with lower losses in
between. If the losses at V
DCIN(MIN)
are significantly
higher than the losses at V
DCIN(MAX)
, consider increas-
ing the size of P1. Conversely, if the losses at
V
DCIN(MAX)
are significantly higher than the losses at
V
DCIN(MIN),
consider reducing the size of P1. If DCIN
does not vary over a wide range, the minimum power
dissipation occurs where the resistive losses equal the
switching losses.
Choose a low-side MOSFET that has the lowest possi-
ble on-resistance (RDS(ON)), comes in a moderate-
sized package, and is reasonably priced. Make sure
that the DLO gate driver can supply sufficient current to
support the gate charge and the current injected into
the parasitic gate-to-drain capacitor caused by the
high-side MOSFET turning on; otherwise, cross-con-
duction problems can occur.
The MAX1909 has an adaptive dead-time circuit that
prevents the high-side and low-side MOSFETs from
conducting at the same time (see
MOSFET Drivers
).
Even with this protection, it is still possible for delays
internal to the MOSFET to prevent one MOSFET from
turning off when the other is turned on.
Select devices that have low turn-off times. To be con-
servative, make sure that P1(t
DOFF
(MAX)) -
N1(t
DON
(MIN)) < 40ns. Failure to do so may result in
efficiency-killing shoot-through currents. If delay mis-
match causes shoot-through currents, consider adding
extra capacitance from gate to source on N1 to slow
down its turn-on time.
MOSFET Power Dissipation
Worst-case conduction losses occur at the duty factor
extremes. For the high-side MOSFET, the worst-case
power dissipation (PD) due to resistance occurs at the
minimum supply voltage:
Generally, a small high-side MOSFET is desired to
reduce switching losses at high input voltages.
However, the RDS(ON) required to stay within package
power-dissipation limits often limits how small the
MOSFET can be. The optimum occurs when the switch-
ing (AC) losses equal the conduction (I
2
R
DS(ON)
)
losses. High-side switching losses do not usually
become an issue until the input is greater than approxi-
P( )
V
V
I
R
BATT
DCIN
LOAD
2
DS ON
(
)
1
2
=
×
REFERENCE QTY
DESCRIPTION
N1/P1
1
Dual N- and P-channel MOSFETs, 7A,
30V and -5A, -30V, 8-pin SO, MOSFET
Fairchild FDS8958A or
Single N-channel MOSFETs, +13.5A,
+30V FDS6670S and
Single P-channel MOSFETs, -13.5A,
-30V FDS66709Z
Single, P-channel, -11A, -30V, 8-pin SO
MOSFETs
Fairchild FDS6675
100k
,
±
5% resistor (0603)
10k
±
1% resistors (0603)
590k
±
1% resistor 0603
196k
±
1% resistor 0603
1M
±
5% resistor (0603)
1k
±
5% resistor (0603)
33
±
5% resistor (0603)
10k
±
5% resistors (0603)
0.01
±
1%, 0.5W sense resistor (2010)
Vishay Dale WSL2010 0.010 1.0%
IRC LRC-LR2010-01-R010-F
0.015
±
1%, 0.5W sense resistor (2010)
Vishay Dale WSL2010 0.015 1.0%
IRC LRC-LR2010-01-R015-F
MAX1909ETI (28-pin thin QFN-EP)
P2, P3, P4
3
R4
1
2
1
1
1
1
1
2
R5, R9, R21
R6
R7
R8
R11
R16
R19, R20
RS1
1
RS2
1
U1
1
Table 2. Recommended Components
(continued)
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相關(guān)代理商/技術(shù)參數(shù) |
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|---|---|
| MAX1909ETI+ | 功能描述:電池管理 Multichemistry Battery Chargers RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel |
| MAX1909ETI+T | 功能描述:電池管理 Multichemistry Battery Chargers RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel |
| MAX1909ETI-T | 功能描述:電池管理 RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel |
| MAX1909EVKIT | 功能描述:電池管理 Evaluation Kit for the MAX1909 RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel |
| MAX190ACNG | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
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