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參數(shù)資料
| 型號： | MAX1870AETJ |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 電源管理 |
| 英文描述： | Step-Up/Step-Down Li+ Battery Charger |
| 中文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, QCC32 |
| 封裝： | 5 X 5 MM, 0.80 MM HEIGHT, MO-220WHHD-2, TQFN-32 |
| 文件頁數(shù)： | 24/32頁 |
| 文件大?。?/td> | 1091K |
| 代理商： | MAX1870AETJ |
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M
Step-Up/Step-Down
Li+ Battery Charger
24
______________________________________________________________________________________
Setting the LTF = 1 to solve for the unity-gain frequency
yields:
For stability, choose a crossover frequency lower than
1/10th of the switching frequency. The crossover fre-
quency must also be below the RHP zero, calculated at
maximum charge current, minimum input voltage, and
maximum battery voltage.
Choosing a crossover frequency of 13kHz and solving for
R
CV
using the component values listed in Figure 1 yields:
MODE = V
CC
(4 cells)
C
OUT
= 22μF
V
BATT
= 16.8V
GMV = 0.1μA/mV
GM
PWM
= 1.85A/V
f
CO_CV
= 13kHz
R
L
= 0.2
f
OSC
= 400kHz
To ensure that the compensation zero adequately can-
cels the output pole, select f
Z_CV
≤
f
P_OUT
.
C
CV
≥
(R
L
/ R
CV
) x C
OUT
C
CV
≥
440pF
Figure 10 shows the Bode Plot of the voltage-loop fre-
quency response using the values calculated above.
Charge-Current and Wall-Adapter-Current
Loop Compensation
When the MAX1870A regulates the charge current or the
wall adapter current, the system stability does not
depend on the output capacitance. The simplified
schematic in Figure 11 describes the operation of the
MAX1870A when the charge-current loop (CCI) is in con-
trol. The simplified schematic in Figure 12 describes the
operation of the MAX1870A when the source-current
R
x C
GMV x GM
x f
k
CV
OUT
CO CV
_
PWM
=
=
2
10
π
f
GM
x G
R
x C
CO CV
_
PWM
MV
CV
OUT
=
2
π
LTF
GM
x
R
sC
G
PWM
CV
OUT
MV
=
Table 3. Constant Voltage Loop Poles and Zeros
NO.
NAME
CALCULATION
DESCRIPTION
1
CCV Pole
Lowest Frequency Pole created by C
CV
and GMV’s finite output
resistance. Since R
OGMV
is very large (R
OGMV
> 10M
), this is
a low-frequency pole.
2
CCV Zero
Voltage-Loop Compensation Zero. If this zero is lower than the
output pole, f
P_OUT
, then the loop transfer function
approximates a single-pole response near the crossover
frequency. Choose C
CV
to place this zero at least 1 decade
below crossover to ensure adequate phase margin.
3
Output
Pole
Outp ut P ol e For m ed w h the E fecti ve Load Resi stance R
L
and the
Outp ut C ap aci ance C
OU T
. R
L
i nfl uences the D C g ai n b ut d oes not
affect the stab y of the system or the cr ossover fr eq uency.
4
Output
Zero
Output ESR Zero. This zero can keep the loop from crossing
unity gain if f
Z_OUT
is less than the desired crossover
frequency. Therefore, choose a capacitor with an ESR zero
greater than the crossover frequency.
5
RHP Zero
S ep U p M od e RH P Z er o. Thi s zer o occur s b ecause of the i ni i al
op p osi ng r esp onse of a step up conver er E for s to i ncr ease the
i nd uctor cur ent r esul i n an i m m ed ate
d ecr ease
i n cur ent
d el ver ed al houg h eventual y r esul i n an i ncr ease i n cur ent
d el ver ed Thi s zer o i s d ep end ent on char g e cur ent and m ay
cause the system to g o unstab e at hi g h cur ents w hen i n step up
m od e. A r g ht- hal - p ane zer o i s d etr m ental to b oth p hase and
g ai n. To ensur e stab y und er m axi m um l oad i n step up m od e,
the cr ossover fr eq uency m ust b e l ow er than hal of f
R H P Z
.
f
x R
C
P CV
_
OGMV
CV
=
1
2
π
f
x R
C
Z CV
_
CV
CV
=
1
2
π
f
x R C
P OUT
_
OUT
=
1
2
π
f
x R
C
Z OUT
_
ESR
OUT
=
1
2
π
f
V
x L I
2
V
x L I
V
RHPZ
IN
L
IN
OUT
OUT
=
=
2
2
π
π
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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 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 |
| MAX1870ETJ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
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