isl88731

Manufacturer Part Numberisl88731
DescriptionSmbus Level 2 Battery Charger
ManufacturerIntersil Corporation
isl88731 datasheet
 


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Data Sheet
SMBus Level 2 Battery Charger
The ISL88731 is a highly integrated Lithium-ion battery
charger controller, programmable over the SMBus system
management bus (SMBus). The ISL88731 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
ISL88731 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 ISL88731 provides 0.5% end-of-charge battery voltage
accuracy.
The ISL88731 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 ISL88731 is available in a small 5mm x 5mm 28 Ld thin
(0.8mm) QFN package. An evaluation kit is available to
reduce design time. The ISL88731 is available in Pb-free
packages.
Pinout
ISL88731
(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
November 20, 2006
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 Plus Anneal Available (RoHS Compliant)
Applications
• Notebook Computers
• Tablet PCs
• Portable Equipment with Rechargeable Batteries
Ordering Information
PART
NUMBER
22
ISL88731HRZ
VDDP
21
(Note)
LGATE
20
ISL88731HRZ-T
(Note)
PGND
19
CSOP
18
NOTE: Intersil Pb-free plus anneal products employ special Pb-free material
sets; molding compounds/die attach materials and 100% matte tin plate
17
CSON
termination finish, which are RoHS compliant and compatible with both SnPb
NC
16
and Pb-free soldering operations. Intersil Pb-free products are MSL classified
at Pb-free peak reflow temperatures that meet or exceed the Pb-free
VFB
15
requirements of IPC/JEDEC J STD-020.
14
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.
ISL88731
FN9258.0
PART
MARKING
TEMP (°C)
PACKAGE
ISL887
-10 to +100 28 Ld 5x5 TQFN
31HRZ
(Pb-free)
ISL887
-10 to +100 28 Ld 5x5 TQFN
31HRZ
(Tape and Reel)
(Pb-free)
Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2006. All Rights Reserved
PKG.
DWG. #
L28.5x5B
L28.5x5B

isl88731 Summary of contents

  • Page 1

    ... The ISL88731 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 ISL88731 is available in a small 5mm x 5mm 28 Ld thin (0.8mm) QFN package. An evaluation kit is available to reduce design time. The ISL88731 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 ISL88731 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 ISL88731 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 Lead Temperature (Soldering, 10s +300° ...

  • Page 4

    ... VDDSMB Quiescent Current V REFERENCE VREF Output Voltage ACOK ACOK Sink Current ACOK Leakage Current ACIN ACIN rising Threshold ACIN Threshold Hysteresis ACIN Input Bias Current SWITCHING REGULATOR Frequency 4 ISL88731 = -10°C to +100°C (Continued) A CONDITIONS Adapter present, not charging CSOP CSON PHASE ...

  • Page 5

    ... SCL Low Period SCL High Period Maximum Charging Period Without a SMBus Write to ChargeVoltage or ChargeCurrent Register NOTE SCL is low for longer than the specified time, the charger is disabled. 4. Guaranteed by characterization. 5 ISL88731 = -10°C to +100°C (Continued) A CONDITIONS UGATE High V = 28V 20V ...

  • Page 6

    ... VDDP LOAD CURRENT (mA) FIGURE 3. VDD LOAD REGULATION 15% 10 -5% -10% -15 ADAPTER CURRENT (A) FIGURE 5. ICM ACCURACY vs AC ADAPTER CURRENT CHARGE CURRENT FIGURE 7. CHARGE ENABLE 6 ISL88731 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 13.0 12.5 12.0 11.5 11.0 10.5 10 FIGURE 6 ...

  • 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 ISL88731 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 ISL88731 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 ISL88731 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 ISL88731 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 temp exceeds +150°C, it stops charging. Once the die temp drops below +125° ...

  • Page 11

    ... Specification V1.1, which can be downloaded from www.smbus.org. The ISL88731 uses the SMBus Read-Word and Write-Word protocols (Figure 18) to communicate with the smart battery. The ISL88731 is an SMBus slave device and does not initiate communication on the bus. It responds to the 7-bit address 0b0001001_ (0x12). ...

  • Page 12

    ... 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 ISL88731 is 16mV because the D0–D3 bits are ignored as shown in Table 2. The D15 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 13

    ... The ISL88731 ignores the first 7 LSBs and uses the next 6 bits to control the current DAC. The charge-current range of the ISL88731 8.064A (using a 10mΩ current-sense resistor). All numbers requesting charge current above 8.064A result in a current setting of 8 ...

  • Page 14

    ... Figure 18). The register code for InputCurrent is 0x3F (0b00111111). The InputCurrent register can be read back to verify its contents. The ISL88731 ignores the first 7 LSBs and uses the next 6 bits to control the input-current DAC. The input-current range of the ISL88731 is from 256mA to 11.004A. All 16-bit numbers requesting input current above 11 ...

  • Page 15

    ... After the Stop condition the master follows with a new Start condition, then sends a new control byte with the ISL88731 slave address and the R/W bit set to 1, indicating a read. The ISL88731 will Acknowledge then send the lower byte stored in that register. After receiving the byte, the master ...

  • Page 16

    ... 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 charger application, the input voltage of the synchronous 16 ISL88731 is in buck converter is equal to the AC adapter output voltage, CO which is relatively constant. The maximum efficiency is achieved by selecting a high side MOSFET that has the conduction losses equal to the switching losses ...

  • Page 17

    ... I appear in some of the equations for poles and zeros in the compensation. PWM Gain F The Pulse Width Modulator in the ISL88731 converts voltage at VCOMP to a duty cycle by comparing VCOMP to a triangle wave (duty = VCOMP/V filter formed by L and C output voltage ( ...

  • Page 18

    ... V (EQ. 17) set by the InputCurrent register, ISL88731 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 19

    ... Voltage Control Loop When the battery is charged to the voltage set by ChargeVoltage register the voltage error amplifier (GMV) 19 ISL88731 takes control of the output (assuming that the adapter current is below the limit set by ACLIM). The voltage error Compensator amplifier (GMV) discharges the cap on VCOMP to limit the Modulator output voltage ...

  • Page 20

    ... F . The low pass filter ZERO2 F2 F2 ISL88731 add a pole and R FILTER 3 divider resistors that set the DC output voltage. For a 3 cell battery 500kΩ and R = 100kΩ. The equations 3 4 following relate the compensation network’s poles, zeros and gain to the components in Figure 23. Figure 25 shows an asymptotic Bode plot of the DC/DC converter’ ...

  • Page 21

    ... TO THE LOW PASS FILTER AND CSOP AND CSON FIGURE 26. CURRENT SENSE RESISTOR LAYOUT 21 ISL88731 CSOP, CSON, CSSP and CSSN Pins Accurate charge current and adapter current sensing is critical for good performance. The current sense resistor connects to the CSON and the CSOP pins through a low pass filter with the filter cap very near the IC (see Figure 2) ...

  • 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 ISL88731 L28.5x5B 28 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE C ...