MAX8857AETL+T [MAXIM]
Power Management Circuit,;
| 型号： | MAX8857AETL+T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Power Management Circuit, 集成电源管理电路 |
| 文件： | 总2页 (文件大小：129K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-0987; Rev 1; 2/12
Smallest, All-Internal MOSFET,
7-Channel 2 AA DSC PMIC
MX857A
General Description
Features
The MAX8857A PMIC provides a complete power-sup-
ply solution for digital still cameras (DSCs) and digital
video cameras (DVCs). The MAX8857A improves per-
formance, component count, and board space utiliza-
tion compared to currently available solutions for 2 AA
cell and dual-battery designs. On-chip power
MOSFETs provide up to 95% efficiency for critical
power supplies. The CCD inverter can operate directly
from 2 AA/NiMH batteries without the use of any addi-
tional external components.
o 95% Efficient Synchronous-Rectified DC-DC
Converters
o 90% Efficient Boost-Buck Operation
o Up to 85% Efficient, High-Voltage DC-DC
Converters
o Inverter Operates Directly from 2 AA Batteries
o Internal Compensation on All Channels
o True Shutdown™ on All Step-Up Converters
o Overload Protection
•
•
•
•
Step-up synchronous-rectified DC-DC converter
(SU). The MAX8857A is bootstrapped from V
.
o Startup into Short Protection
SU
MAIN synchronous-rectified step-up DC-DC converter
(M) with active discharge for DSP I/O supply voltage.
o Soft-Start for Controlled Startup Current
o 100% Duty Cycle on Step-Down Converters
o Regulated Current Output for Up to 6 White LEDs
o PWM Dimming of WLED Current
SDZ synchronous-rectified step-down DC-DC con-
verter (Z) for DSP DDR supply voltage.
Low-voltage (down to 1V) synchronous-rectified
step-down DC-DC converter (SD) for DSP core sup-
ply voltage.
o Adjustable LED Overvoltage Protection Up to 27V
o Transformerless Inverting Converter for CCD
o 2MHz 2.5% Switching ꢀreꢁuency
o 1µA Shutdown Supply Current
•
Step-up DC-DC converter with current regulation
and PWM dimming control (LEDBST) for up to 6
series white LEDs (WLED).
o CCD Voltage Seꢁuencing
•
•
High-voltage step-up DC-DC converter (CCDBST)
for CCD imagers or positive LCD bias supplies.
o All Internal Power MOSꢀETs
o SDOK Power-OK Indicator
Transformerless inverting DC-DC converter (CCDINV)
for CCD imagers or negative LCD bias supplies. This
converter can connect directly to 2 AA batteries.
Typical Operating Circuit
The MAX8857A has an independent/simultaneous
power-on sequence of the CCDBST and CCDINV con-
verters. For a preset power-on sequence of CCDBST
before CCDINV, contact the factory.
INPUT
1.8V TO 5.5V
V
V
5V
SU STEP-UP
SU
PVBST
ONSU
ONM
MAIN STEP-UP
3.3V
2.5V
MAIN
The MAX8857A is available in a 5mm x 5mm, 40-pin thin
QFN package and operates over the -40°C to +85°C
extended temperature range.
V
V
1.8V
SD STEP-DOWN
SDZ STEP-DOWN
SD
Applications
DDRZ
ONSD
ONZ
DSCs and DVCs
PDAs and Portable Media Players
MAX8857A
Ordering Information
SDOK
TEMP
PKG
LEDBST
CCDBST
CCDINV
V
V
UP TO 6 WLEDs
+15V
LEDBST
PART
PIN-PACKAGE
ONLED
ONBST
ONINV
RANGE
CODE
CCDBST
-40°C to 40 Thin QFN-EP*
+85°C 5mm x 5mm x 0.8mm
MAX8857AETL+
T4055-2
V
-7.5V
CCDINV
MAX8857AETL+ -40°C to 40 Thin QFN-EP*
TCBR +85°C 5mm x 5mm x 0.8mm
T4055-2
+Denotes a lead-free package.
Pin Configuration appears at the end of data sheet.
*EP = Exposed paddle.
Note: Contact factory for the option where CCDBST must
reach regulation before the INV converter can be turned on.
True Shutdown is a trademark of Maxim Integrated Products, Inc.
________________________________________________________________ Maxim Integrated Products
1
ꢀor pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Smallest, All-Internal MOSFET,
7-Channel 2 AA DSC PMIC
V
REF
V
BATT
C20
0.1µF
C18
1µF
16
24
REF
V
BATT
V
CCDINV
PVINV
D3
(1.8V TO 5.5V)
(-7.5V, 100mA)
15
LXINV
C1
C2
22µF
22µF
L7
10µH
L1
2µH
C19
10µF
R13
604kΩ
32
31
29
30
LXSU
MX857A
23
17
LXSU
FBINV
V
SU
PVSU
PVSU
SWBST
R14
100kΩ
(5V, 500mA)
C3
22µF
C4
22µF
L6
2.2µH
R17
100Ω
V
REF
MAX8857A
V
CCDBST
D2
R1
402kΩ
(15V, 30mA)
26
27
20
22
LXBST
SU
C21
0.1µF
C17
PGBST
(EP)
2.2µF
R11
1.4MΩ
FBSU
FBBST
PVBST
R12
PGSU
(EP)
R2
100kΩ
100kΩ
V
V
C16
1µF
BATT
BATT
V
BATT
C5
1µF
18
39,
40
LXM
PVM
C14
L2
1µH
1µF
V
MAIN
13
14
PVLED
SWLED
(3.3V, 300mA)
1, 2
3
L5
4.7µH
V
LEDBST
C6
22µF
C7
22µF
D1
(16V, 25mA)
R3
23.2kΩ
C15
3.3µF
R9
D7
D6
D5
D4
11
10
FBM
PGM
(EP)
LXLED
OVLED
1.6MΩ
R4
10kΩ
V
C23
1µF, OPTIONAL
SU
V
BATT
C8
R10
100kΩ
10µF
19
9
PVGD
34
35
PVSD
LXSD
L3
4.7µH
V
FBLED
SD
(1.8V, 250mA)
PGLED
(EP)
EP
C10
C9
10µF
10µF
R5
80.6kΩ
R15
10Ω
25
36
7
V
GND
PVZ
SU
C11
1µF
FBSD
PGSD
(EP)
R6
100kΩ
L4
4.7µH
28
4
V
DDRZ
(2.5V, 200mA)
V
BATT
ONSU
ONM
37
LXZ
V
SU
C12
10µF
C13
10µF
33
12
R7
NOTE 1:
ONSD
150kΩ
ALL ON_ PINS HAVE INTERNAL 1MΩ
PULLDOWN TO GROUND.
ONLED
5
6
FBZ
21
8
ONBST
ONINV
PGZ
(EP)
NOTE 2:
R8
100kΩ
R16
100kΩ
ALL CONVERTERS’ POWER GROUND
CONNECTIONS ARE THROUGH THE
EXPOSED PADDLE (EP).
38
ONZ
SDOK
V
BATT
Figure 1. MAX8857A Typical Application Circuit
14 ______________________________________________________________________________________
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