isl88731a

Manufacturer Part Numberisl88731a
DescriptionSmbus Level 2 Battery Charger
ManufacturerIntersil Corporation
isl88731a datasheet
 


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Data Sheet
SMBus Level 2 Battery Charger
The ISL88731A is a highly integrated Lithium-ion battery
charger controller, programmable over the SMBus system
management bus (SMBus). The ISL88731A is intended to be
used in a smart battery charger (SBC) within a smart battery
system (SBS) that throttles the charge power such that the
current from the AC-adapter is automatically limited. High
efficiency is achieved with a DC/DC synchronous-rectifier
buck converter, equipped with diode emulation for enhanced
light load efficiency and system bus boosting prevention. The
ISL88731A charges one to four Lithium-ion series cells, and
delivers up to 8A charge current. Integrated MOSFET
drivers and bootstrap diode result in fewer components and
smaller implementation area. Low offset current-sense
amplifiers provide high accuracy with 10mΩ sense resistors.
The ISL88731A provides 0.5% end-of-charge battery
voltage accuracy.
The ISL88731A provides a digital output that indicates the
presence of the AC-adapter as well as an analog output
which indicates the adapter current within 4% accuracy.
The ISL88731A is available in a small 5mmx5mm 28 Ld thin
(0.8mm) QFN package. An evaluation kit is available to
reduce design time. The ISL88731A is available in Pb-Free
packages.
Pinout
ISL88731A
(28 LD TQFN)
TOP VIEW
28
27
26
25
24
23
NC
1
ACIN
2
VREF
3
ICOMP
4
NC
5
VCOMP
6
NC
7
8
9
10
11
12
13
1
January 7, 2009
Features
• 0.5% Battery Voltage Accuracy
• 3% Adapter Current Limit Accuracy
• 3% Charge Current Accuracy
• SMBus 2 Wire Serial Interface
• Battery Short Circuit Protection
• Fast Response for Pulse-Charging
• Fast System-Load Transient Response
• Monitor Outputs
- Adapter Current (3% Accuracy)
- AC-Adapter Detection
• 11-Bit Battery Voltage Setting
• 6 Bit Charge Current/Adapter Current Setting
• 8A Maximum Battery Charger Current
• 11A Maximum Adapter Current
• +8V to +28V Adapter Voltage Range
• Pb-Free (RoHS compliant)
Applications
• Notebook Computers
• Tablet PCs
• Portable Equipment with Rechargeable Batteries
Ordering Information
PART
NUMBER
22
(Note)
VDDP
21
ISL88731AHRZ
LGATE
20
ISL88731AHRZ-T* ISL887
PGND
19
CSOP
18
*Please refer to TB347 for details on reel specifications.
17
CSON
NOTE: These Intersil Pb-free plastic packaged products employ special
NC
16
Pb-free material sets, molding compounds/die attach materials, and
100% matte tin plate plus anneal (e3 termination finish, which is RoHS
VFB
15
compliant and compatible with both SnPb and Pb-free soldering
operations). Intersil Pb-free products are MSL classified at Pb-free peak
14
reflow temperatures that meet or exceed the Pb-free requirements of
IPC/JEDEC J STD-020.
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
|
1-888-INTERSIL or 1-888-468-3774
All other trademarks mentioned are the property of their respective owners.
ISL88731A
FN6738.1
TEMP
PART
RANGE
PACKAGE
MARKING
(°C)
(Pb-Free)
ISL887
-10 to +100 28 Ld 5x5
31AHRZ
TQFN
-10 to +100 28 Ld 5x5
31AHRZ
TQFN (Tape
and Reel)
Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2008, 2009. All Rights Reserved
PKG.
DWG. #
L28.5x5B
L28.5x5B

isl88731a Summary of contents

  • Page 1

    ... The ISL88731A provides a digital output that indicates the presence of the AC-adapter as well as an analog output which indicates the adapter current within 4% accuracy. The ISL88731A is available in a small 5mmx5mm 28 Ld thin (0.8mm) QFN package. An evaluation kit is available to reduce design time. The ISL88731A is available in Pb-Free packages ...

  • Page 2

    ... EN GMS + CSO - GMI DC/DC + CONVERTER LVB LVB DACV + GMV - CSSP RS1 CSSP CSSN UGATE ACIN PHASE DCIN ISL88731A BOOT LGATE CSOP CSON VFB ICOMP VCOMP PGND VDDP VREF ACOK ICM SDA SCL VCC VDDSMB GND AGND REFERENCE VREF ACOK ACIN ICM ...

  • Page 3

    ... CSOP to CSON Full-Scale Current-Sense Voltage Charge Current and Accuracy Charge Current Gain Error CSOP/CSON Input Voltage Range 3 ISL88731A Thermal Information Thermal Resistance (Typical, Notes 1, 2) θ QFN Package Junction Temperature Range .-55°C to +150°C Operating Temperature Range . . . . . . . . . . . . . . . .-10°C to +100°C Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . .-65°C to +150°C Pb-Free Reflow Profile ...

  • Page 4

    ... VREF Output Voltage ACOK ACOK Sink Current ACOK Leakage Current ACIN ACIN rising Threshold ACIN Threshold Hysteresis ACIN Input Bias Current 4 ISL88731A = -10°C to +100°C. Parameters with MIN and/or MAX limits are 100% tested A CONDITIONS Adapter present, not charging ...

  • Page 5

    ... Maximum Charging Period Without a SMBus Write to ChargeVoltage or ChargeCurrent Register NOTES SCL is low for longer than the specified time, the charger is disabled. 4. Limits established by characterization and are not production tested. 5 ISL88731A = -10°C to +100°C. Parameters with MIN and/or MAX limits are 100% tested A CONDITIONS UGATE High V ...

  • Page 6

    ... VDDP LOAD CURRENT (mA) FIGURE 3. VDD LOAD REGULATION -10 - ADAPTER CURRENT (A) FIGURE 5. ICM ACCURACY vs AC-ADAPTER CURRENT CHARGE CURRENT FIGURE 7. CHARGE ENABLE 6 ISL88731A DCIN = 20V, 3S2P Li-Battery +25°C, unless otherwise noted. A 3.23 3.22 3.21 3.20 3.19 3.18 3.17 80 100 0 FIGURE 4. VREF LOAD REGULATION 13.0 12.5 12.0 11.5 11.0 10 ...

  • Page 7

    ... Typical Operating Performance UGATE PHASE FIGURE 9. SWITCHING WAVEFORMS AT DIODE EMULATION FIGURE 11. BATTERY REMOVAL ADAPTER CURRENT FIGURE 13. LOAD TRANSIENT RESPONSE 7 ISL88731A DCIN = 20V, 3S2P Li-Battery +25°C, unless otherwise noted. (Continued) A LGATE INDUCTOR CURRENT FIGURE 10. SWITCHING WAVEFORMS IN CC MODE CSON/ V BATTERY BATTERY ...

  • Page 8

    ... AC-adapter output. ACOK AC Detect Output. This open drain output is high impedance when ACIN is greater than 3.2V. The ACOK output remains low when the ISL88731A is powered down. Connect a 10k pull-up resistor from ACOK to VDDSMB. ICM Input Current Monitor Output. ICM voltage equals ...

  • Page 9

    ... This speeds the transition from voltage loop control to current loop control or vice versa. The ISL88731A can operate up to 99.6% duty cycle if the input voltage drops close to or below the battery charge voltage (drop out mode). The DC/DC converter has a timer to prevent the frequency from dropping into the audible frequency range ...

  • Page 10

    ... Undervoltage Detect and Battery Trickle Charging If the voltage at CSON falls below 2.5V, the ISL88731A reduces the charge current limit to 128mA to trickle charge the battery. When the voltage rises above 2.7V the charge current reverts to the programmed value in the ChargeCurrent register. Over-Temperature Protection If the die temperature exceeds +150°C, it stops charging. ...

  • Page 11

    ... The control byte begins with a Start condition, followed by 7-bits of slave address (0001001 for the ISL88731A) followed by the R/W bit. The R/W bit is 0 for a write or 1 for a read. If any slave devices on the SMBus bus recognize their address, they will Acknowledge by pulling the serial data (SDA) line low for the last clock cycle in the control byte ...

  • Page 12

    ... Specification V1.1, which can be downloaded from www.smbus.org. The ISL88731A uses the SMBus Read-Word and Write-Word protocols (Figure 19) to communicate with the smart battery. The ISL88731A is an SMBus slave device and does not initiate communication on the bus. It responds to the 7-bit address 0b0001001_ (0x12). ...

  • Page 13

    ... ChargeVoltage is 0x15. The 16-bit binary number formed by D15–D0 represents the charge voltage set point in mV. However, the resolution of the ISL88731A is 16mV because the D0–D3 bits are ignored as shown in Table 2. The D-5 bit is also ignored because it is not needed to span the 1.024V to 19.2V range. Table 2 shows the mapping between the charge-voltage set point and the 16-bit number written to the ChargeVoltage register ...

  • Page 14

    ... Setting Charge Current ISL88731A has a 16-bit ChargeCurrent register that sets the battery charging current. ISL88731A controls the charge current by controlling the CSOP-CSON voltage. The register’s LSB translates to 10µV at CSON-CSOP. With a 10mΩ charge current R resistor (RS2 in Figure 2), the sense LSB translates to 1mA charge current ...

  • Page 15

    ... Figure 19). The register code for InputCurrent is 0x3F (0b00111111). The InputCurrent register can be read back to verify its contents. The ISL88731A ignores the first 7 LSBs and uses the next 6 bits to control the input-current DAC. The input-current range of the ISL88731A is from 256mA to 11.004A. All 16-bit numbers requesting input current above 11 ...

  • Page 16

    ... In order to set the charge current, charge voltage or input current, valid 16-bit numbers must be written to ISL88731A’s internal registers via the SMBus. To write to a register in the ISL88731A, the master sends a control byte with the R/W bit set to 0, indicating a write receives an Acknowledge from the ISL88731A it sends a register address byte setting the register to be written (i ...

  • Page 17

    ... AC-adapter output voltage does not exceed 25V. Therefore, 30V logic MOSFET should be used. The high-side MOSFET must be able to dissipate the conduction losses plus the switching losses. For the battery 17 ISL88731A less than charger application, the input voltage of the synchronous ...

  • Page 18

    ... Substituting I = 24mA and f GATE into Equation 11 yields that the total gate charge should be less than 80nC. Therefore, the ISL88731A easily drives the battery charge current up to 8A. Snubber Design ISL88731A's buck regulator operates in discontinuous current mode (DCM) when the load current is less than half the peak-to-peak current in the inductor ...

  • Page 19

    ... V (EQ. 17) set by the InputCurrent register, ISL88731A will reduce the current to the battery and/or reduce the output voltage to hold the adapter current at the limit. Above the adapter current limit, the minimum current buffer equals the output of GMS and ICOMP controls the charger output ...

  • Page 20

    ... Voltage Control Loop When the battery is charged to the voltage set by 20 ISL88731A ChargeVoltage register the voltage error amplifier (GMV) takes control of the output (assuming that the adapter Compensator current is below the limit set by ACLIM). The voltage error ...

  • Page 21

    ... F ZERO1 information is added to the feedback to create a second zero F . The low pass filter ZERO2 F2 F2 ISL88731A add a pole FILTER 3 divider resistors that set the DC output voltage. For a 3-cell battery 500kΩ and R = 100kΩ. Equations 23 through relate the compensation network’ ...

  • Page 22

    ... However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries. For information regarding Intersil Corporation and its products, see www.intersil.com 22 ISL88731A HIGH RESISTOR CURRENT ...

  • Page 23

    ... L28.5x5B 28 LEAD THIN QUAD FLAT NO-LEAD PLASTIC PACKAGE Rev 1, 10/07 5.00 6 PIN 1 INDEX AREA (4X) 0.15 TOP VIEW ( 4. 65 TYP ) ( 3. 25) TYPICAL RECOMMENDED LAND PATTERN 23 ISL88731A 28X 0.55 ± 0. ± 0.05 ( 24X 0 . 50) (28X 28X 0 . 75) NOTES: 1. Dimensions are in millimeters. Dimensions ...