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參數(shù)資料
| 型號： | MAX1870A |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Step-Up/Step-Down Li+ Battery Charger |
| 中文描述： | 升/降壓型Li+電池充電器 |
| 文件頁數(shù)： | 25/32頁 |
| 文件大?。?/td> | 1091K |
| 代理商： | MAX1870A |
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M
Step-Up/Step-Down
Li+ Battery Charger
______________________________________________________________________________________
25
loop (CCS) is in control. Since the output capacitor’s
impedance has little effect on the response of the current
loop, only a single pole is required to compensate this
loop. A
CSI
and A
CSS
are the internal gains of the current-
sense amplifiers. RS2 is the charge current-sense resis-
tor. RS1a and RS1b are the adapter current-sense
resistors. R
OGMI
and R
OGMS
are the equivalent output
impedance of the GMI and GMS amplifiers, which are
greater than 10M
. GMI is the charge-current amplifier
transconductance (2.4μA/mV). GMS is the adapter-cur-
rent amplifier transconductance (1.7μA/mV.) GM
PWM
is
the DC-DC converter transconductance (1.85A/V).
Use the following equation to calculate the loop transfer
function:
which describes a single-pole system. Since GM
PWM
=
1
A
x RS
CS_
_
the loop-transfer function simplifies to:
Use the following equations to calculate the crossover
frequency:
For stability, choose a crossover frequency lower than
1/10th of the switching frequency and lower than half of
the RHP zero.
C
CI
= 10 GMI / (2
π
x f
OSC
), C
CS
= 10 GMS / (2
π
x f
OSC
)
This zero is inversely proportional to charge current
and may cause the system to go unstable at high cur-
rents when in step-up mode. A right-half-plane zero is
detrimental to both phase and gain. To also ensure sta-
bility under maximum load in step-up mode, the CCI
crossover frequency must also be lower than f
RHPZ
.
The right-half-plane zero does not affect CCS.
Choosing a crossover frequency of 30kHz and using
the component values listed in Figure 1 yields C
CI
and
C
CS_
> 10nF. Values for C
CI
/ C
CS
greater than ten
times the minimum value may slow down the current
loop response excessively. Figure 13 shows the Bode
Plot of the input-current frequency response using the
values calculated above.
MOSFET Drivers
DHI and DBST are optimized for driving moderately-
sized power MOSFETs. Use low-inductance and low-
resistance traces from driver outputs to MOSFET gates.
DHI typically sources 1.6A and sinks 0.8A to or from
the gate of the p-channel MOSFET. DHI swings from
VHP to VHN. VHN is a negative LDO that regulates with
respect to VHP to provide high-side gate drive.
Connect VHP to DCIN. Bypass VHN with a 1μF capaci-
tor to VHP.
f
V
π
x L I
V
L I
V
RHPZ WorstCase
_
IN MIN
_
L
IN MIN
_
OUTMAX
OUTMAX
=
=
2
2
2
π
f
GMI
C
2
π
f
GMS
C
2
π
CO CI
_
CI
CO CS
_
CS
,
=
=
LTF
GM
R
sR
x C
OGM
OGM
C
=
+
_
_
_
_
1
LTF
GM
x A
x RS
x GM
R
sR
x C
PWM
CS
OGM
OGM
C
=
+
_
_
_
_
_
_
1
CCV LOOP RESPONSE
M
-135
-90
-45
0
80
60
40
20
-40
-20
0
1.E+001.E+011.E+021.E+031.E+041.E+051.E+06
1.E-01
FREQUENCY (Hz)
MAG
PHASE
Figure 10. CCV Loop Response
GM
PWM
REF
GMI
R
OGMI
C
CI
CCI
RS2
A
CSI
CSI
Figure 11. CCI Simplified Loop Diagram
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX1870AETJ | Step-Up/Step-Down Li+ Battery Charger |
| MAX1873 | Simple Current-Limited Switch-Mode Li Charger Controller |
| MAX1873SEEE | Simple Current-Limited Switch-Mode Li Charger Controller |
| MAX1873REEE | Simple Current-Limited Switch-Mode Li Charger Controller |
| MAX1873TEEE | Simple Current-Limited Switch-Mode Li Charger Controller |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1870AETJ | 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 |
| MAX1870AETJ+ | 功能描述:電池管理 Li+ Step Up/Step Down Battery Charger 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 |
| MAX1870AETJ+T | 功能描述:電池管理 Li+ Step Up/Step Down Battery Charger 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 |
| MAX1870AETJ-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 |
| MAX1870AEVKIT | 功能描述:電源管理IC開發(fā)工具 Evaluation Kit for the MAX1870A RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
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