MAX8845ZEVKIT+ [MAXIM]
Programmable Top-Off Current Threshold;
| 型号： | MAX8845ZEVKIT+ |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Programmable Top-Off Current Threshold |
| 文件： | 总11页 (文件大小：154K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-4405; Rev 0; 12/08
MAX8845Z Evaluation Kit
Evluates:Z/MAX845Y
General Description
Features
The MAX8845Z evaluation kit (EV kit) is a fully assem-
bled and tested PCB for evaluating the MAX8845Z/
MAX8845Y 28V linear Li+ battery chargers.
o CCCV, Thermally Regulated Linear Single-Cell Li+
Battery Charger
o No External MOSFET, Reverse-Blocking Diode, or
The MAX8845Z EV kit features an overvoltage-protect-
ed LDO output (SAFEOUT) for low-voltage-rated USB
or charger inputs in the system, and a battery pack
detection circuit (DETBAT) that disables the IC when
the battery pack is absent. The IC disables charging if
the input sources exceed 7.5V to protect against
unqualified or faulty AC adapters. The MAX8845Z EV kit
also features an adjustable fast-charge current set by
an external resistor (R1) and an adjustable top-off cur-
rent threshold set by an external resistor (R2).
Current-Sense Resistor
o Programmable Fast-Charge Currents (1A
max)
RMS
o Programmable Top-Off Current Threshold
o Input Overvoltage-Protected 4.7V Output
(SAFEOUT) from DC
o Proprietary Die Temperature Regulation Control
(+115°C)
o 4.25V to 28V Input-Voltage Range with Input
Other features include an active-low control input (EN)
and an active-low input power source detection output
(POK). The IC also contains a booting assistant circuit
that distinguishes input sources and battery connec-
tion, and provides an output signal (MAX8845Z = ABO,
MAX8845Y = ABO) for system booting.
Overvoltage Protection Above +7.5V
o Low-Dropout Voltage (300mV at 500mA)
o Input Power-Source Detection Output (POK),
Charge Status Output (CHG), and Charge-Enable
Input (EN)
To evaluate the MAX8845Y version, order the
MAX8845YETC+ along with the MAX8845ZEVKIT+ and
see the Evaluating the MAX8845Y section.
o Output for Autobooting (MAX8845Z = ABO,
MAX8845Y = ABO)
o Lead(Pb)-Free and RoHS Compliant
Ordering Information
PART
TYPE
MAX8845ZEVKIT+
EV Kit
+Denotes lead(Pb)-free and RoHS compliant.
Component List
DESIGNATION QTY
DESCRIPTION
DESIGNATION QTY
DESCRIPTION
1µF 10ꢀ, ꢁ5V X5R ceramic
capacitor (060ꢁ)
1µF 10ꢀ, 10V X5R ceramic
capacitor (0402)
C1
C2
Cꢁ
1
1
1
C4
1
Taiyo Yuden GMK107BJ105KA
Murata GRM155R61A105K
C5
0
2
Not installed, capacitor
2.2µF 10ꢀ, 10V X5R ceramic
capacitor (060ꢁ)
Taiyo Yuden LMK107BJ225KA
Murata GRM188R61A225KEꢁ4
Red LEDs
Panasonic LNJ208R8ARA
D1, D2
2-pin headers, 0.1in center
Sullins PECꢁ6SAAN
Digi-Key S1012E-ꢁ6-ND
JU1–JU4
R1
4
1
0.1µF 10ꢀ, 16V X7R ceramic
capacitor (0402)
TDK C1005X7R1C68ꢁK
2.80kΩ 1ꢀ resistor (0402)
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAX8845Z Evaluation Kit
Component List (continued)
DESIGNATION QTY
DESCRIPTION
DESIGNATION QTY
DESCRIPTION
1.74kΩ 1ꢀ resistor (0402)
200Ω 5ꢀ resistors (0402)
4.7kΩ 5ꢀ resistor (0402)
R2
Rꢁ, R4
R5
1
2
1
28V linear Li+ battery charger
(12 Thin QFN-EP*)
Maxim MAX8845ZETC+
(Top Mark: ABL)
U1
1
1
Not installed, resistors—PCB short
(0402)
R6, R7
R8
0
1
—
PCB: MAX8845Z Evaluation Kit+
200kΩ 5ꢀ resistor (0402)
*EP = Exposed pad.
Component Suppliers
SUPPLIER
PHONE
WEBSITE
Digi-Key Corp.
800-344-4539
770-436-1300
800-344-2112
760-744-0125
800-348-2496
847-803-6100
www.digikey.com
Murata Electronics North America, Inc.
Panasonic Corp.
www.murata-northamerica.com
www.panasonic.com
Sullins Electronics Corp.
Taiyo Yuden
www.sullinselectronics.com
www.t-yuden.com
TDK Corp.
www.component.tdk.com
Note: Indicate that you are using the MAX8845Z when contacting these component suppliers.
4) Verify that a shunt is installed on JU2 (DETBAT).
Quick Start
Recommended Equipment
• 4V to 28V adjustable power supply (PS1) capable of 1A
5) Verify that JUꢁ and JU4 are open and shunts are
not installed.
6) Connect the positive lead of the power supply (PS1)
to the EV kit pad labeled IN. Connect the negative
lead of the power supply to the EV kit pad labeled
GND.
• One 5V power supply (PS2) capable of 100mA
• Three digital multimeters (DMM1, DMM2, DMMꢁ)
• One 10A ammeter
Evluates:Z/MAX845Y
7) Connect the positive lead of the power supply (PS2)
to the EV kit pad labeled VI/O. Connect the negative
lead of the power supply to the EV kit pad labeled
GND.
• One single-cell lithium-ion (Li+) battery (not fully
charged)
Procedure
The MAX8845Z EV kit is a fully assembled and tested
surface-mount board. Follow the steps below and
Figure 1 to set up and verify the MAX8845Z and board
operation:
8) Observe correct Li+ cell polarity. Connect the sin-
gle-cell Li+ battery and 10A ammeter, as shown in
Figure 1. The positive lead of the ammeter must
connect to BATT+ and the negative lead to the pos-
itive terminal of the Li+ battery.
1) Preset the power supply (PS1) to 5V. Turn off the
power supply. Do not turn on the power supply
until all connections are completed.
9) Connect a digital multimeter (DMM1) across the Li+
battery. Connect the positive lead of DMM1 to the
positive terminal of the Li+ battery. Connect the
negative lead of DMM1 to the negative terminal of
the Li+ battery and note the battery voltage. If
2) Preset the power supply (PS2) to 5V. Turn off the
power supply. Do not turn on the power supply
until all connections are completed.
V
< 2.5V, the charger starts in precharge
BATT
mode. If V
ꢁ) Verify that a shunt is installed on JU1 (EN) to set the
≥ 2.5V, the charger starts up in fast-
BATT
EV kit in disable mode.
charge mode.
2
_______________________________________________________________________________________
MAX8845Z Evaluation Kit
Evluates:Z/MAX845Y
10) Connect a digital multimeter (DMM2) from ABO
(MAX8845Z only) to GND.
Detailed Description of Hardware
The MAX8845Z/MAX8845Y chargers use voltage, cur-
rent, and thermal-control loops to charge a single Li+
cell and protect the battery. When a Li+ battery with a
cell voltage below 2.5V is inserted, the MAX8845Z/
MAX8845Y chargers enter a prequalification stage
where it precharges that cell with 10ꢀ of the user-pro-
grammed fast-charge current. The CHG indicator is dri-
ven low to indicate entry into the prequalification state.
When the battery voltage exceeds 2.5V, the IC soft-
starts as it enters the fast-charge stage. The fast-
charge current level is programmed through a resistor
from SETI to GND. As the battery voltage approaches
4.2V, the battery current is reduced. If the battery cur-
rent drops to less than the top-off current threshold set
11) Connect a digital multimeter (DMMꢁ) from SAFEOUT
to GND.
12) Turn on PS1 and then turn on PS2.
1ꢁ) Remove the shunt on JU1 to set the EV kit in enable
mode.
14) Verify that D2 is emitting light, indicating that POK is
low and input power is valid.
15) Verify that the voltage read by DMMꢁ is approxi-
mately 4.7V.
16) If the charger is in fast-charge mode, verify that the
ammeter reads approximately 500mA. If the charg-
er is in precharge mode, verify that the ammeter
reads approximately 50mA.
by R
, the IC enters top-off mode and the CHG indi-
MIN
cator goes high impedance, signaling that the battery
is fully charged.
17) Verify that D1 is emitting light, indicating that CHG
is low and the battery charger is on.
Overvoltage-Protected Output (SAFEOUT)
SAFEOUT is a linear regulator that provides an output
voltage of 4.7V and can be used to supply low-voltage-
rated charging systems. The SAFEOUT linear regulator
Note: If the battery is fully charged, D1 will not emit
light.
18) Verify that the voltage read by DMM2 is approxi-
mately the same voltage read by DMM1.
turns on when V ≥ 4.25V regardless of EN and is dis-
IN
abled when V is greater than the overvoltage thresh-
19) When the battery is fully charged, DMM1 reads 4.2V.
IN
old (7.5V typ).
20) Remove the shunt on JU2 and verify that D1 and D2
are not emitting light.
Battery Pack Detection Input (DETBAT)
DETBAT is a battery pack ID resistor detector that
enables the battery charger if pulled low through a
resistor that is < 51kΩ. By installing a header on JU2,
DETBAT is pulled to ground through R5 (4.7kΩ). If
DETBAT is left unconnected, or the pulldown resistor
is 51kΩ or greater, the battery charger is disabled. If
DETBAT is not used, connect DETBAT to GND for nor-
mal operation.
21) Install a shunt on JU2.
22) Turn off the input power supply (PS1).
2ꢁ) Verify that D2 is not emitting light and the voltage
read by DMM2 is 0V.
24) Install a shunt on JU4.
25) Verify that the voltage read at DMM2 is approxi-
mately the same voltage read by DMM1.
POK Output
26) Turn on PS1 and increase to 8V.
The open-drain POK output asserts low when 2.ꢁ5V ≤
27) Verify that D1 and D2 are not emitting light and the
voltage read by DMMꢁ is 0V.
V
≤ 7V, (V - V
) ≥ 40mV (typ V rising), and
BATT IN
IN
IN
DETBET is pulled low through a resistor that is < 51kΩ.
POK is high impedance during shutdown. When inter-
facing with a microprocessor logic input, a pullup resis-
tor to the microprocessor’s I/O voltage may be required.
When evaluation of the MAX8845Z EV kit is completed,
use the following steps to power down the EV kit:
1) Install a shunt on JU1.
2) Turn off both power supplies.
ꢁ) Remove the battery.
Autobooting Assistant
The MAX8845Z/MAX8845Y contain an autobooting
assistant circuit that generates an enable signal for sys-
tem booting (MAX8845Z = ABO, MAX8845Y = ABO).
For the MAX8845Z, the booting assistant functions as an
internal OR gate (refer to the MAX8845Z/MAX8845Y IC
data sheet). The first input is dependent on the input
4) Disconnect all test leads from the EV kit.
supply voltage V and DETBAT, while the second input
IN
_______________________________________________________________________________________
3
MAX8845Z Evaluation Kit
POWER
SUPPLY (PS1)
-
+5V
+
- DMM3
+
D1 IS ON WHEN BATTERY CHARGING.
10A
D1
SETI
MIN
AMMETER
BATT+
BATT-
DETBAT
+
Li+
DMM1
MAX8845Z
EVALUATION KIT+
SHUNT INSTALLED = BATTERY PRESENT.
SHUNT NOT INSTALLED = BATTERY ABSENT.
-
JU2
JU4
SHUNT INSTALLED = ABI CONNECTED TO VI/O.
SHUNT NOT INSTALLED = ABI UNCONNECTED.
JU3
ABI
(ABO)
ABO
JU1
D2
+
DMM2 -
POWER
-
SUPPLY (PS2) +
+5V
SHUNT INSTALLED = ABO - MAX8845Y ONLY.
SHUNT NOT INSTALLED = ABO - MAX8845Z ONLY.
D2 IS ON WHEN POWER
SUPPLY IS VALID.
SHUNT INSTALLED = IC DISABLED.
SHUNT NOT INSTALLED = IC ENABLED.
( ) = MAX8845Y ONLY.
Evluates:Z/MAX845Y
Figure 1. Test Procedure Setup for MAX8845Z EV Kit
Table 1. Jumper Settings (JU1–JU4)
DEFAULT
SETTINGS
JUMPER
FUNCTION
JU1 connects EN (active-low enable input) to VI/O (system supply). Install a shunt on JU1 to disable
the IC. EN has an internal pulldown resistor to GND. Remove the shunt from JU1 to enable the IC.
JU1
JU2
Installed
Installed
JU2 connects DETBAT (battery pack ID resistor detection input) to GND through R5. Install a shunt
on JU2 to simulate battery present. Remove the shunt on JU2 to simulate battery absent.
Remove the shunt on JUꢁ to evaluate the MAX8845Z with an active-high autobooting logic output
JUꢁ
JU4
Not installed (ABO). Install a shunt on JUꢁ to connect ABO to the VI/O supply through R8 in order to achieve a
logic-high output on the drain of the internal open-drain MOSFET (MAX8845Y only).
JU4 connects ABI (autobooting input) to VI/O (system supply). Install a shunt on JU4 to connect ABI
to VI/O. Remove the shunt on JU4 to leave ABI unconnected and when ABI is driven by an external
source.
Not installed
4
_______________________________________________________________________________________
MAX8845Z Evaluation Kit
Evluates:Z/MAX845Y
ampere of charging current. The output voltage at SETI
is proportional to the charging current:
is an external signal applied to ABI. The first input (POK)
is driven high once DETBAT is pulled low through a
resistor < 51kΩ, 2.ꢁ5V ≤ V ≤ 7V, and (V - V ) ≥
IN
IN
BATT
I
× R
SETI
1016
40mV (typ V rising).
CHARGE
IN
V
=
SETI
The second input signal (ABI) is driven by an external
source (see Table 2). ABI enables an autoboot signal
when a battery is connected at BATT and is indepen-
dent of POK. If POK is pulled low, the booting assistant
always drives ABO high (MAX8845Z), regardless of ABI.
ABI is pulled to GND through an internal 200kΩ resistor.
If ABI is supplied from an outside exposed pin, an RC
filter (R1/Cꢁ in Figure 2) is required for ESD protection
and noise filtering. If ABI is supplied by a system’s inter-
nal GPIO, or logic, the RC filter is not required.
The voltage at SETI is nominally 1.4V at the selected
fast-charge current, and falls with charging current as
the cell becomes fully charged or as the thermal-
regulation circuitry activates.
Top-Off Current Threshold Setting
The top-off current threshold is programmed by an
external resistor connected from MIN to GND (R2 in
Figure 2). Use the following equation to determine the
top-off current (I
):
MIN
For the MAX8845Y, the output ABO is only dependent
on the state of ABI (Table 2).
140V
I
=
MIN
R
Charger Enable Input
The MAX8845Z EV kit contains an active-low logic input
(EN) used to enable the IC. Drive EN low, leave JU1
unconnected, or connect EN to GND to enable the
charge-control circuitry. Drive EN high to disable the
charge-control circuitry. EN has an internal 200kΩ pull-
down resistor.
MIN
where I
is in amperes and R
is in ohms.
MIN
MIN
Thermal Regulation
The thermal-regulation loop limits the MAX8845Z/
MAX8845Y die temperature to +115°C by reducing the
charge current, as necessary. This feature not only pro-
tects the IC from overheating, but also allows a higher
charge current without risking damage to the IC.
Fast-Charge Current Setting
The maximum charging current is programmed by an
external resistor connected from SETI to GND (R1 in
Figure 2). Use the following equation to determine the
Evaluating the MAX8845Y
To evaluate the MAX8845Y version, order the
MAX8845YETC+ along with the MAX8845ZEVKIT+.
Remove U1 and replace with the MAX8845YETC+ (Top
Mark: ABM) and install a shunt on JUꢁ. The MAX8845Y
features an active-low autobooting logic output (ABO)
and requires an external power supply (VI/O on the
MAX8845Z EV kit) to achieve logic-high.
fast-charge current (I
):
FAST_CHARGE
1400V
I
=
FAST_ CHARGE
R
SETI
where I
is in amperes and R
is in
SETI
FAST_CHARGE
ohms. R
must always be 1.40kΩ or higher due to
SETI
To evaluate the MAX8845Y and board operation, see
Figures 1 and ꢁ and follow the procedure on the next
page. The MAX8845Y procedure is similar to the
MAX8845Z procedure with a few minor differences.
the continuous charging current limit of 1A. The voltage
at SETI can be used to monitor the fast-charge current
level. The output current from SETI is 1016µA per
Table 2. Autobooting Output States
ABI
BATT
CHARGER STATE
ABO (MAX8845Z)
POK
ABO (MAX8845Y)
Low
Present
High impedance
Shutdown
Low
High impedance
High
Low
Low
High
Present
Not present
Present
High impedance
Shutdown
High
High
High
High
Low
Low
Low
Low
Fast charge/top off
Fast charge/top off
Fast charge/top off
High impedance
High impedance
Low
Present
Note: Present indicates that V
≥ 2V and not present indicates that battery is not connected.
BATT
_______________________________________________________________________________________
5
MAX8845Z Evaluation Kit
MAX8845Y Procedure
Follow the steps below and Figure 1 to set up and verify
the MAX8845Y and board operation:
1ꢁ) Remove the shunt on JU1 to set the EV kit in enable
mode.
14) Verify that D2 is on indicating POK is low and input
1) Preset the power supply (PS1) to 5V. Turn off the
power supply. Do not turn on the power supply
until all connections are completed.
power is valid.
15) Verify that the voltage read by DMMꢁ is approxi-
mately 4.7V.
2) Preset the power supply (PS2) to 5V. Turn off the
power supply. Do not turn on the power supply
until all connections are completed.
16) If the charger is in fast-charge mode, verify that the
ammeter reads approximately 500mA. If the charg-
er is in precharge mode, verify that the ammeter
reads approximately 50mA.
ꢁ) Verify that a shunt is installed on JU1 (EN) to set the
EV kit in disable mode.
17) Verify that D1 is on indicating that CHG is low and
4) Verify that a shunt is installed on JU2 (DETBAT).
the battery charger is on.
5) Verify that a shunt is installed on JUꢁ. Verify that a
shunt is installed on JU4.
Note: If the battery is fully charged, D1 will not turn
on.
6) Connect the positive lead of the power supply (PS1)
to the EV kit pad labeled IN. Connect the negative
lead of the power supply to the EV kit pad labeled
GND.
18) Verify that the voltage read by DMM2 is 0V.
19) When the battery is fully charged, DMM1 reads
4.2V.
20) Remove the shunt on JU2 and verify that D1 and D2
are not emitting light.
7) Connect the positive lead of the power supply (PS2)
to the EV kit pad labeled VI/O. Connect the negative
lead of the power supply to the EV kit pad labeled
GND.
21) Install a shunt on JU2.
22) Turn off the input power supply (PS1).
8) Observe correct Li+ cell polarity. Connect a single-
cell Li+ battery and 10A ammeter, as shown in
Figure 1. The positive lead of the ammeter must
connect to BATT+ and the negative lead to the pos-
itive terminal of the Li+ battery.
2ꢁ) Verify that D2 is not emitting light and that the volt-
age read by DMM2 is approximately 5V.
24) Remove the shunt on JU4.
25) Verify that the voltage read by DMM2 is approxi-
mately 5V.
9) Connect a digital multimeter (DMM1) across the Li+
battery. Connect the positive lead of DMM1 to the
positive lead of the Li+ battery. Connect the nega-
tive lead of DMM1 to the negative terminal of the
26) Turn on PS1 and increase to 8V.
27) Verify that D1 and D2 are not emitting light and that
the voltage read by DMMꢁ is 0V.
Evluates:Z/MAX845Y
Li+ battery and note the battery voltage. If V
<
BATT
When evaluation of the MAX8845Y is completed, use
the following steps to power down the EV kit:
2.5V, the charger starts in precharge mode. If
≥ 2.5V the charger starts up in fast-charge
V
BATT
mode.
1) Ensure a shunt on JU1.
2) Turn off both power supplies.
ꢁ) Remove the battery.
10) Connect a digital multimeter (DMM2) from ABO to
GND.
11) Connect a digital multimeter (DMMꢁ) from SAFEOUT
to GND.
4) Disconnect all test leads from the EV kit.
12) Turn on PS1 and then turn on PS2.
6
_______________________________________________________________________________________
MAX8845Z Evaluation Kit
Evluates:Z/MAX845Y
12
11
2
SAFEOUT
SAFEOUT
DETBAT
DETBAT
C4
1μF
JU2
R5
4.7kΩ
9
8
IN
IN
MIN
C1
1μF
U1
R2
1.74kΩ
GND
MAX8845Z
VI/O
BATT
BATT+
C2
2.2μF
R6
JU4
PCB SHORT
BATT-
EN
3
ABI
ABI
C3
0.1μF
VI/O
VI/O
R8
200kΩ
JU1
4
EN
VI/O
R4
200Ω
JU3
7
(ABO)
ABO
ABO
D2
VI/O
6
1
POK
SETI
POK
SETI
R7
PCB SHORT
R3
200Ω
C5
OPEN
R1
2.80kΩ
D1
10
CHG
CHG
GND
EP
5
( ) - MAX8845Y ONLY.
Figure 2. MAX8845Z EV Kit Schematic
_______________________________________________________________________________________
7
MAX8845Z Evaluation Kit
12
2
SAFEOUT
SAFEOUT
DETBAT
DETBAT
C4
1μF
JU2
R5
4.7kΩ
11
9
8
IN
IN
MIN
C1
1μF
U1
R2
1.74kΩ
GND
MAX8845Y
VI/O
BATT
BATT+
C2
2.2μF
R6
JU4
PCB SHORT
BATT-
EN
3
ABI
ABI
C3
0.1μF
VI/O
VI/O
R8
200kΩ
JU1
4
EN
VI/O
R4
200Ω
JU3
7
(ABO)
ABO
ABO
D2
VI/O
6
1
POK
SETI
POK
SETI
R7
PCB SHORT
R3
200Ω
C5
OPEN
R1
2.80kΩ
D1
10
Evluates:Z/MAX845Y
CHG
CHG
GND
EP
5
( ) - MAX8845Y ONLY.
Figure ꢁ. MAX8845Y EV Kit Schematic
8
_______________________________________________________________________________________
MAX8845Z Evaluation Kit
Evluates:Z/MAX845Y
Figure 4. MAX8845Z EV Kit Component Placement Guide—Component Side
_______________________________________________________________________________________
9
MAX8845Z Evaluation Kit
Evluates:Z/MAX845Y
Figure 5. MAX8845Z EV Kit PCB Layout—Component Side
10 ______________________________________________________________________________________
MAX8845Z Evaluation Kit
Evluates:Z/MAX845Y
Figure 6. MAX8845Z EV Kit PCB Layout—Solder Side
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 11
© 2008 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
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