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bq2007
Fast-Charge IC
Features
Fast charging and conditioning of NiCd and NiMH batteries
-
Audible alarm for charge completion and fault conditions
General Description
The bq2007 is a highly integrated monolithic CMOS IC designed to provide intelligent battery charging and charge status monitoring for standalone charge systems. The bq2007 provides a wide variety of charge status display formats. The bq2007 internal charge status monitor supports up to a seven-segment bar graph or a single BCD digit display. The bar graph display indicates up to seven monotonic steps, whereas the BCD digit counts in ten steps of 10% increments. The bq2007 output drivers can direct-drive either an LCD or LED display. Charge action begins either by application of the charging supply or by replacement of the battery pack. For safety, charging is inhibited until battery temperature and voltage are within configured limits.
-
Precise charging independent of battery pack number of cells Discharge-before-charge on demand Pulse trickle charge conditioning Battery undervoltage and overvoltage protection
Charge control flexibility
-
Fast or Standard speed charging Top-off mode for NiMH Charge rates from C 8 to 2C (30 minutes to 8 hours)
Charge termination by: Negative delta voltage (- V) Peak voltage detect (PVD) Maximum voltage Maximum time Maximum temperature
Built-in 10-step voltage-based charge status monitoring
-
Charge status display options include seven-segment monotonic bar graph and fully decoded BCD digit Display interface options for direct drive of LCD or LED segments Charger state status indicators for pending, discharge, charge, completion, and fault
High-efficiency switch-mode design Ideal for small heat-sensitive enclosures
24-pin, 300-mil SOIC or DIP
Pin Connections
Pin Names
SEGC/ MSEL SEGB SEGA Display output segment C/ driver mode select Display output segment B TS Display output segment A DIS LED1 LED2 INH COM ALARM TM VSEL FAST DCMD TCO Charge status output 1 Charge status output 2 Charge inhibit input Common LED/LCD output Audio alarm output Timer mode select Voltage termination select Fast charge rate select Discharge command Temperature cutoff SEGE / DSEL2 SEGD / DSEL1 Display output segment E / display select 2 Display output segment D / display select 1
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SNS BAT
Sense resistor input Battery voltage Temperature sense Discharge control System ground 5.0V 10% power Modulation control Display output segment G / charge status display select Display output segment F / multi-cell pack select
SEGC/MSEL SEGB SEGA LED1 LED2 INH COM ALARM TM VSEL FAST DCMD
1 2 3 4 5 6 7 8 9 10 11 12
24 23 22 21 20 19 18 17 16 15 14 13
SEGD/DSEL1 SEGE/DSEL2 SEGF/MULT SEGG/QDSEL MOD VCC VSS DIS TS BAT SNS TCO
VSS VCC MOD SEGG / QDSEL SEGF / MULT
24-Pin Narrow DIP or SOIC
PN200701.eps
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The acceptable battery temperature range is set by an internal low-temperature threshold and an external high-temperature cutoff threshold. The absolute temperature is monitored as a voltage on the TS pin with the external thermistor network shown in Figure 2. The bq2007 provides for undervoltage battery protection from high-current charging if the battery voltage is less than the normal end-of-discharge value. In the case of a deeply discharged battery, t h e bq2007 enters the charge-pending state and attempts trickle-current conditioning of the battery until the voltage increases. Should the battery voltage fail to increase above the discharge value during the undervoltage time-out period, a fault condition is indicated. Discharge-before-charge may be selected to automatically discharge the battery pack on battery insertion or with a push-button switch. Discharge-before-charge on demand provides conditioning services that are useful to correct or prevent the NiCd voltage depression, or "memory" effect, and also provide a zero capacity reference for accurate capacity monitoring. After prequalification and any required dischargebefore-charge operations, charge action begins until one of the full-charge termination conditions is detected. The bq2007 terminates charging by any of the following methods: Negative delta voltage (- V) Peak voltage detect (PVD) Maximum absolute temperature Maximum battery voltage Maximum charge time-out The bq2007 may be programmed for negative delta voltage (- V) or peak voltage detect (PVD) charge termination algorithms. The VSEL input pin selects - V or PVD termination to match the charge rate and battery characteristics. To provide maximum safety for battery and system, charging terminates based on maximum temperature cutoff (TCO), maximum cutoff voltage (MCV), and maximum time-out (MTO). The TCO threshold is the maximum battery temperature limit for charging. TCO terminates charge action when the temperature sense input voltage on the TS pin drops below the TCO pin voltage threshold. MCV provides battery overvoltage protection by detecting when the battery cell voltage (VCELL = VBAT - VSNS) exceeds the VMCV value and terminates fast charge, standard charge, or top-off charge. The maximum time-out (MTO) termination occurs when the charger safety timer has completed during the active charge state. QDSEL MULT DSEL1- DSEL2 The bq2007 indicates charge state status with an audio alarm output option and two dedicated output pins with programmable display options. The DSEL1-2 inputs can select one of the three display modes for the LED1-2 outputs. Charger status is indicated for: Charge pending Charge in progress Charge complete Fault condition
Pin Descriptions
SEGA-G Display output segments A-G State-of-charge monitoring outputs. QDSEL input selects the bar graph or BCD digit display mode. See Table 3. MSEL Display driver mode select Soft-programmed input selects LED or LCD driver configuration at initialization. When MSEL is pulled up to VCC, outputs SEGA-G are LED interface levels; when MSEL is pulled down to VSS, outputs SEGA-G are LCD levels. Display mode select 1-2 Soft-programmed inputs control the LED1--2 charger status display modes at initialization. See Table 2. Fixed-cell pack select Soft-programmed input is pulled up to VCC when charging multi-cell packs and is pulled down to VSS for charging packs with a fixed number of cells. State-of-charge display select The QDSEL input controls the SEGA-G state-of-charge display modes. See Table 3. LED1- LED2 Charger status outputs 1-2 Charger status output drivers for direct drive of LED displays. Display modes are selected by the DSEL input. See Table 2. INH Charge inhibit input When low, the bq2007 suspends all charge actions, drives all outputs to high impedance, and assumes a low-power operational state. When transitioning from low to high, a charge cycle is initiated. See page 10 for details.
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COM Common LCD/LED output Common output for LCD/LED display SEGA--G. Output is high-impedance during initialization to allow reading of soft-programmed inputs DSEL1, DSEL2, MSEL, MULT, and QDSEL. ALARM Audio output Audio alarm output. TM Timer mode select TM is a three-level input that controls the settings for charge control functions. See Table 5. VSEL Voltage termination select This input switches the voltage detect sensitivity. See Table 5. FAST Fast charge rate select The FAST input switches between Fast and Standard charge rates. See Table 4. DCMD Discharge command The DCMD input controls the dischargebefore-charge function. A negative-going pulse initiates a discharge action. If DCMD is connected to VSS, automatic dischargebefore-charge is enabled. See Figure 3. TCO Temperature cut-off threshold input Minimum allowable battery temperaturesensor voltage. If the potential between TS and SNS is less than the voltage at the TCO input, then any fast charging or top-off charging is terminated. SNS Sense resistor input SNS controls the switching of MOD output based on an external sense resistor. This provides the lower reference potential for the BAT pin and the TS pin. BAT Battery voltage input Battery voltage sense input referenced to SNS for the battery pack being charged. This resistor divider network is connected between the positive and the negative terminals of the battery. See Figure 1. VSS VCC MOD TS Temperature sense input Input referenced to SNS for battery temperature monitoring negative temperature coefficient (NTC) thermistor. DIS Discharge control DIS is a push-pull output that controls an external transistor to discharge the battery before charging. Ground VCC supply input Current-switching control output Push/pull output that controls the charging current to the battery. MOD switches high to enable current flow and low to inhibit current flow.
Functional Description
Figure 1 illustrates charge control and display status during a bq2007 charge cycle. Table 1 summarizes the bq2007 operational features. The charge action states a n d control outputs a r e given for possible i n p u t conditions.
Charge Action Control
The bq2007 charge action is controlled by input pins DCMD, VSEL, FAST, and TM. When charge action is initiated, the bq2007 enters the charge-pending state, checks for acceptable battery voltage and temperature, and performs any r equired discharge-before-charge operations. DCMD controls the discharge-before-charge function, and VSEL, FAST, and TM select the charger configuration. See Tables 4 and 5. During charging, the bq2007 continuously tests for charge termination conditions: negative delta voltage, peak voltage detection, maximum t ime-out, battery over-voltage, and high-temperature cutoff. When the charge state is terminated, a trickle charge continues to compensate for self-discharge and maintain the fully charged condition.
Charge Status Indication
Table 2 summarizes the bq2007 charge status display indications. The charge status indicators include the DIS output, which can be used to indicate the discharge state, the audio ALARM output, which indicates charge completion and fault conditions, and t he dedicated status outputs, LED1 and LED2.
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Charge Pending
(Pulse-Trickle)
Discharge
(Optional)
Fast Charging
Top-Off
(Optional)
Pulse-Trickle
DIS
260 s Note
MOD or MOD
(Switching Configuration) 2080 s 260 s 260 s Note
(External Regulation)
Mode 1, LED2 Status Output
2080 s
260 s
Mode 1, LED1 Status Output
Mode 2, LED2 Status Output
Mode 2, LED1 Status Output
Mode 3, LED2 Status Output
Mode 3, LED1 Status Output
Battery discharged to VEDV or battery within temperature/voltage limits. (Discharge-before-charge not qualified by temperature.) Low-voltage fault: Battery voltage less than VEDV for under-voltage time-out. Charge initiated. Battery outside temperature/voltage limits. Note: See Table 4 for pulse-trickle period.
TD200701.eps
Figure 1. Example Charging Action Events
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Outputs LED1-2 have three display modes that are selected at initialization by the input pins DSEL1 and DSEL2. The DSEL1 and DSEL2 input pins, when pulled down to VSS , are intended for implementation of a simple two-LED system. LED2 indicates the precharge status (i.e., charge pending and discharge) and LED1 indicates the charge status (i.e., charging and completion). DSEL1 pulled up to VCC and DSEL2 pulled down to VSS mode is for implementation of a single tri-color LED such that discharge, charging, and completion each have a unique color. DSEL1 pulled down to VSS and DSEL2 pulled up to VCC allows for fault status information to be displayed.
Charge Status Monitoring
The bq2007 charge status monitor may display the battery voltage or charge safety timer as a percentage of the full-charged condition. These options are selected with the MULT soft-programmed input pin. When MULT is pulled down to VSS, the battery charge status is displayed as a percentage of the battery voltage, and the single-cell battery voltage at the BAT pin is compared with internal charge voltage reference thresholds. When VBAT is greater than the internal thresholds of V20, V40, V60, or V80, the respective 20%, 40%, 60%, or 80% display outputs are activated. The b a t t e r y v o l t a g e d i r e c t l y i n d i c a t e s 20% c h a r g e increments, while the 10% charge increments use a timer that is a function of the charge safety timer. When MULT is pulled down to VSS and when VBAT exceeds V20 during charging, the 20% charge indication is activated and the timer begins counting for a period equal to 1 64 to 1 32 of the charge safety time-out period. When the timer count is completed, the 30% charge indication is activated. Should VBAT exceed V40 prior to the timer count completion, the charge status monitor activates the 30% and 40% indications. This technique
Audio Output Alarm
The bq2007 audio alarm output generates an audio tone to indicate a charge completion or fault condition. The audio alarm output is a symmetrical duty-cycle AC signal that is compatible with standard piezoelectric alarm elements. A valid battery insertion is indicated by a single high-tone beep of 1 2-second typical duration. The charge completion and fault conditions are indicated by a 9.5- to 15-second high-tone sequence of 1 2-second typical duration at a 2-second typical repetition rate.
Table 1. bq2007 Operational Summary
Charge Action State Battery absent Charge initiation Discharge-beforecharge Charge pending Fast charging Standard charging Charge complete Top-off pending Top-off charging Trickle charging Fault Definitions: Conditions VCC applied and VCELL VMCV VCC applied or VCELL drops from VMCV to < VMCV DCMD high-to-low transition or to VSS on charge initiation and VEDV < VCELL < VMCV Charge initiation occurred and VTEMP VLTF or VTEMP VTCO or VCELL < VEDV Charge pending complete and FAST = VCC Charge pending complete and FAST = VSS MOD Output Trickle charge per Table 4 Low Trickle charge per Table 4 Low if VSNS > 250mV; high if VSNS < 200mV Low if VSNS > 250mV; high if VSNS < 200mV DIS Output Low Low High Low Low Low Low
- V termination or VTEMP < VTCO or PVD 0 to -3mV/cell or maximum time-out or VCELL > VMCV VSEL = VCC, charge complete and VTEMP VLTF or Trickle charge per Table 4 VTEMP VTCO or VCELL < VEDV VSEL = VCC and charge complete and Activated per VSNS for time-out not exceeded and VTEMP > VTCO and 73ms of every 585ms VCELL < VMCV Charge complete and top-off disabled or Trickle charge per Table 4 top-off complete or pending Charge pending state and charge pending Trickle charge per Table 4 time-out (tPEND) complete
Low Low Low
VCELL = VBAT - VSNS; VMCV = 0.8 * VCC; VEDV = 0.262 * VCC or 0.4 * VCC; VTEMP = VTS - VSNS; VLTF = 0.5 * VCC.
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is used for all the odd percentage charge indications to assure a monotonic charge status display. When MULT is pulled up to VCC, the bq2007 charge status monitor directly displays 1 32 of the charge safety timer as a percentage of full charge. This method is recommended over the voltage-based method when charging fixed-cell packs where the battery terminal voltages can vary greatly between packs. This method offers an accurate charge status indication when the battery is fully discharged. When using the timer-based method, discharge-before-charge is recommended. During discharge with MULT pulled down to VSS, the charge status monitor indicates the percentage of the battery voltage by comparing VBAT to the internal discharge voltage reference thresholds. In BCD format, the discharge thresholds V80, V60, V40, and V20 correspond to a battery charge state indication of 90%, 70%, 50%, and 30%, respectively. In bar graph format, the same discharge thresholds correspond to a battery charge state indication of 90%, 60%, 40%, and 30%, respectively. Differences in the battery charge state indications are due to the finer granularity of the BCD versus the bar graph format. During discharge and when MULT is pulled up to VCC, the state-of-charge monitor BCD format displays the discharge condition, letter "d," whereas the bar graph format has no indication. The charge status display is blanked during the charge pending state and when the battery pack is removed.
Charge Status Display Modes
The bq2007 charge status monitor can be displayed in two modes summarized in Table 3. The display modes ar e a seven-segment monotonic bar graph or a sevensegment BCD single-digit format. When QDSEL is pulled down to VSS, pins SEGA-G drive the decoded seven segments of a single BCD digit display, and when QDSEL is pulled up to VCC, pins SEGA-G drive the seven segments of a bar graph display. In the bar graph display mode, outputs SEGA-G allow options for a three-segment to seven-segment bar graph display. The three-segment charge status display uses outputs SEGB, SEGD, and SEGF for 30%, 60%, and 90% charge indications, respectively. The four-segment charge status display uses outputs SEGA, SEGC, SEGD, and SEG E for 20%, 40%, 60%, a n d 80% indications, respectively. The seven-segment charge status monitor uses all segments. The BCD display mode drives pins SEGA-G with the decoded seven-segment single-digit information. The display indicates in 10% increments from a BCD zero count at charge initiation to a BCD nine count indicating 90% charge capacity. Charge completion is indicated by the letter "F," a fault condition by the letter "E," and the discharge condition by the letter "d." See Table 3.
Table 2. bq2007 Charge Status Display Summary
Mode Charge Action State Battery absent Charge pending (temp. limit, low voltage) DSEL1 = L DSEL2 = L (Mode 1) Discharge in progress Charging Charge complete Fault (low-voltage time-out) Battery absent DSEL1 = H DSEL2 = L (Mode 2) Discharge in progress, pending Charging Charge complete Fault (low-voltage time-out) Battery absent Charge pending (temp. limit, low voltage) DSEL1 = L DSEL2 = H (Mode 3) Discharge in progress Charging Charge complete Fault (low-voltage time-out) Note: LED1 0 0 0 Flashing 1 0 0 1 1 0 0 0 0 0 Flashing 1 0 LED2 0 Flashing 1 0 0 0 0 1 0 1 0 0 Flashing Flashing 0 0 1 DIS 0 0 1 0 0 0 0 1 0 0 0 0 0 1 0 0 0 ALARM 0 0 0 0 High tone High tone 0 0 0 High tone High tone 0 0 0 0 High tone High tone
1 = on; 0 = off; L = pulled down to VSS; H = pulled up to VCC.
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Display Driver Modes
The bq2007 is designed to interface with LCD or LED type displays. The LED signal levels are driven when the MSEL soft-programmed input is pulled to VCC at initialization. The output pin COM is the common anode connection for LED SEGA-G. The LCD interface mode is enabled when the MSEL soft-programmed input pin is pulled to VSS at initialization. An internal oscillator generates all the timing signals required for the LCD interface. The output pin COM is the common connection for static direct-driving of the LCD display backplane and is driven with an AC signal at the frame period. When enabled, each of the SEGA-G pins is driven with the correct-phase AC signal to activate the LCD segment. In bar graph or BCD mode, output pins SEGA-G interface to LED or LCD segments.
Battery Voltage and Temperature Measurement
The battery voltage and temperature are monitored within set minimum and maximum limits. When MULT is pulled up to VCC, battery voltage is sensed at the BAT pin by a resistive voltage divider that divides the terminal voltage between 0.262 VCC (VEDV) and 0.8 VCC (VMCV). The bq2007 charges multi-cell battery packs from a minimum of N cells, to a maximum of 1.5 N cells. The battery voltage divider is set to the minimum cell battery pack (N) by the BAT pin voltage divider ratio equation: R1 N =( )- 1 R2 1.33 When MULT is pulled down to VSS , tighter charge voltage limits and voltage-based charge status display are selected. This is recommended for charging packs with a fixed number of cells where the battery voltage divider range is between 0.4 VCC (VEDV) and 0.8
Table 3. bq2007 Charge Status Display Summary
Mode Display Indication 20% charge 30% charge 40% charge QDSEL = H 60% charge 80% charge 90% charge Charge complete 0% charge--digit 0 10% charge--digit 1 20% charge--digit 2 30% charge--digit 3 40% charge--digit 4 50% charge--digit 5 QDSEL = L 60% charge--digit 6 70% charge--digit 7 80% charge--digit 8 90% charge--digit 9 Charge complete--letter F Fault condition--letter E Discharge--letter d Note: SEGA 1 1 1 1 1 1 1 1 0 1 1 0 1 1 1 1 1 1 1 0 SEGB 0 1 1 1 1 1 1 1 1 1 1 1 0 0 1 1 1 0 0 1 SEGC 0 0 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 0 0 1 SEGD 0 0 0 1 1 1 1 1 0 1 1 0 1 1 0 1 1 0 1 1 SEGE 0 0 0 0 1 1 1 1 0 1 0 0 0 1 0 1 0 1 1 1 SEGF 0 0 0 0 0 1 1 1 0 0 0 1 1 1 1 1 1 1 1 0 SEGG 0 0 0 0 0 0 1 0 0 1 1 1 1 1 0 1 1 1 1 1
1 = on; 0 = off; L = pulled down to VSS; H = pulled up to VCC.
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VCC BAT
R1
VCC TS N T C
bq2007
SNS
R2
bq2007
SNS RSNS RSNS VSS
VSS
BAT Voltage Connection
Thermistor Connection
NTC = negative temperature coefficient thermistor.
FG200701.eps
Figure 2. Voltage and Temperature Limit Measurement
VCC(VMCV). The bq2007 charges fixed-cell battery packs of N cells. The battery voltage divider is set by the divider ratio equation: R1 N =( )- 1 R2 2 Note: The resistor-divider network impedance should be above 200K to protect the bq2007. When battery temperature is monitored for maximum and minimum allowable limits, the bq2007 requires that the thermistor used for temperature measurement have a negative temperature coefficient. See Figure 2. the low-voltage threshold (VEDV). The battery voltage (VCELL) is compared to the low-voltage threshold (VEDV) and charge will be inhibited if VCELL < VEDV. The condition trickle current and fault time-out are a percentage of the fast charge rate and maximum time-out (MTO).
Initiating Charge Action and Discharge-Before-Charge
A charge action is initiated under control of: (1) battery insertion or (2) power applied. Battery insertion is detected when the voltage at the BAT pin falls from above VMCV to below VMCV. Power applied is detected by the rising edge of VCC when a battery is inserted. Discharge-before-charge (see Figure 3) is initiated automatically on application of power or battery insertion when DCMD is connected to VSS. Discharge-on-demand
Temperature and Voltage Prequalifications
For charging to be initiated, the battery temperature must fall within predetermined acceptable limits. The voltage on the TS pin (VTS) is compared to an internal lowtemperature fault threshold (VLTF) of (0.5 VCC) and the high temperature cutoff voltage (VTCO) on the TCO pin. For charging to be initiated, VTS must be less than VLTF and greater than VTCO. Since VTS decreases as temperature increases, the TCO threshold should be selected to be lower than 0.5 VCC for proper operation. If the battery temperature is outside these limits, the bq2007 holds the charge-pending state with a pulse trickle current until the temperature is within limits. Temperature prequalification and termination is disabled if VTS is greater than 0.8 VCC. See Figure 2. The bq2007 provides undervoltage battery protection by trickle-current conditioning of a battery that is below
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DCMD
DCMD
bq2007
bq2007
Always Discharge
Discharge on Command
Figure 3. Discharge-Before-Charge
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Table 4. bq2007 Charge Action Control Summary
FAST Input State VSS VSS VSS VCC VCC VCC TM Input State Float VSS VCC Float VSS VCC Time-out Period (min) 640 (C 8) 320 (C 4) 160 (C 2) 160 (
C 2)
MOD Duty Cycle 25% 25% 25% 100% 100% 100%
Hold-off period (sec) 2400 1200 600 600 300 150
Trickle Rep Rate - V C 32 219Hz 109Hz 55Hz 219Hz 109Hz 55Hz
Trickle Rep Rate PVD C 64 109Hz 55Hz 27Hz 109Hz 55Hz 27Hz
80 (C) 40 (2C)
is initiated by a negative-going pulse on the DCMD pin regardless of charging activity. The DCMD pin is internally pulled up to VCC; therefore, not connecting this pin results in disabling the discharge-before-charge function. When the discharge begins, the DIS output goes high to activate an external transistor that connects a load to the battery. The bq2007 terminates dischargebefore-charge by detecting when the battery cell voltage is less than or equal to the end-of-discharge voltage (VEDV).
Voltage Termination Hold-off
To prevent early termination due to an initial false peak battery voltage, the - V and PVD terminations are disabled during a short "hold-off" period at the start of charge. During the hold-off period when fast charge is selected (FAST = 1), the bq2007 will top off charge to prevent excessive overcharging of a fully charged battery. Once past the initial charge hold-off time, the termination is enabled. TCO and MCV terminations are not affected by the hold-off time.
Charge State Actions
Once the required discharge is completed and temperature and voltage prequalifications are met, the charge state is initiated. The charge state is configured by the VSEL, FAST, and TM input pins. The FAST input selects between Fast and Standard charge rates. The Standard charge rate is 1 4 of the Fast charge rate, which is accomplished by disabling the regulator for a period of 286s of every 1144s (25% duty cycle). In addition to throttling back the charge current, time-out and hold-off safety time are increased accordingly. See Table 4. The VSEL input selects the voltage termination method. The termination mode sets the top-off state and trickle charge current rates. The TM input selects the Fast charge rate, the Standard rate, and the corresponding charge times. Once charging begins at the Fast or Standard rate, it continues until terminated by any of the following conditions: Negative delta voltage (- V) Peak voltage detect (PVD) Maximum temperature cutoff (TCO) Maximum time-out (MTO) Maximum cutoff voltage (MCV)
-V or PVD Termination
Table 5 summarizes the two modes for full-charge voltage t ermination detection. When VSEL = VSS , negative delta voltage detection occurs when the voltage seen on the BAT pin falls 12mV (typical) below the maximum sampled value. VSEL = VCC selects peak voltage detect termination and the top-off charge state. PVD termination occurs when the BAT pin voltage falls 6mV per cell below the maximum sampled value. When charging a battery pack with a fixed number of cells, the - V and PVD termination thresholds are -6mV and 0 to -3mV per cell, respectively. The valid battery voltage range on VBAT for - V or PVD termination is from 0.262 VCC to 0.8 VCC.
Table 5. VSEL Configuration
VSEL VSS VCC Detection Method - V PVD Top-Off Disabled Enabled Pulse Trickle Rate
C 32
C
64
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Maximum Temperature, Maximum Voltage, and Maximum Time Safety Terminations
The bq2007 also terminates charge action for maximum temperature cutoff (TCO), maximum cutoff voltage (MCV), and maximum time-out (MTO). Temperature is monitored as a voltage on the TS pin (VTS), which is compared to a n internal high-temperature cutoff threshold of VTCO. The TCO reference level provides the m a x i m u m l i m i t for b a t t e r y t e m p e r a t u r e d u r i n g charging. MCV termination occurs when VCELL > VMCV. The maximum time-out (MTO) termination is when the charger safety timer countdown has completed during the active charge state. If the MTO, MCV, or TCO limit is exceeded during Fast charge, Standard charge, or top-off states, charge action is terminated.
DC Source
Switch
bq2007
MOD
Battery Under Charge
SNS RSNS
Figure 4. Constant-Current Switching Regulation
Top-Off and Pulse Trickle Charging
The bq2007 provides a post-detection timed charge capability called top-off to accommodate battery chemistries that may have a tendency to terminate charge prior to achieving full capacity. When VSEL = VCC, the top-off state is selected; charging continues after Fast charge termination for a period equal to the time-out value. In top-off mode, the Fast charge control cycle is modified so that MOD is activated for a pulse output of 73ms of every 585ms. This results in a rate 1 8 that of the Fast charge rate. Top-off charge is terminated by maximum temperature cutoff (TCO), maximum cutoff voltage (MCV), or maximum time-out termination. Pulse trickle is used to compensate for self-discharge while the battery is idle and to condition a depleted low-voltage battery to a valid voltage prior to highcurrent charging. The battery is pulse trickle charged when Fast, Standard, or top-off charge is not active. The MOD output is active for a period of 286s of a period specified in Table 4. This results in a trickle rate of C C 64 for PVD and 32 when - V is enabled.
Charge Inhibit
Fast charge, top-off, and pulse trickle may be inhibited by using the INH input pin. When low, the bq2007 suspends all charge activity, drives all outputs to high impedance, and assumes a low-power operational state. When INH returns high, a fast-charge cycle is qualified and begins as soon as conditions allow.
Charge Current Control
The bq2007 controls charge current through the MOD output pin. In a frequency-modulated buck regulator configuration, the control loop senses the voltage at the SNS pin and regulates to maintain it between 0.04 VCC and 0.05 VCC. The nominal regulated current is I REG = 0.225V/RSNS. See Figure 4. MOD pin is switched high or low depending on the voltage input to the SNS pin. If the voltage at the SNS pin is less than VSNSLO (0.04 VCC nominal), the MOD output is switched high to gate charge current through the inductor to the battery. When the SNS voltage is greater than VSNSHI (0.05 VCC nominal), the MOD output is switched low-shutting off charge current from the supply. The MOD pin can be used to gate an external charging current source. When an external current source is used, no sense resistor is required, and the SNS pin is connected to VSS.
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Absolute Maximum Ratings
Symbol VCC VT TOPR TSTG TSOLDER Note: Parameter VCC relative to VSS DC voltage applied on any pin excluding VCC relative to VSS Operating ambient temperature Storage temperature Soldering temperature Minimum -0.3 -0.3 -20 -40 Maximum +7.0 +7.0 +70 +85 +260 Unit V V C C C Commercial Notes
Permanent device damage may occur if Absolute Maximum Ratings are exceeded. Functional operation should be limited to the Recommended DC Operating Conditions detailed in this data sheet. Exposure to conditions beyond the operational limits for extended periods of time may affect device reliability. (TA = TOPR; VCC = 5V 10%) Rating 0.05 * VCC 0.04 * VCC 0.5 * VCC VTCO 0.262 * VCC 0.4 * VCC 0.8 * VCC
187 320
DC Thresholds
Symbol VSNSHI VSNSLO VLTF VHTF
VEDV
VMCV V20 V40 V60 V80 V20 V40 V60 V80
Parameter High threshold at SNS resulting in MOD = Low Low threshold at SNS resulting in MOD = High TS pin low-temperature threshold TS pin high-temperature threshold End-of-discharge voltage MULT is pulled up to VCC End-of-discharge voltage MULT is pulled down to VSS BAT pin maximum cell voltage threshold 20% state-of-charge voltage threshold at the BAT pin 40% state-of-charge voltage threshold at the BAT pin 60% state-of-charge voltage threshold at the BAT pin 80% state-of-charge voltage threshold at the BAT pin 20% state-of-charge voltage threshold at the BAT pin 40% state-of-charge voltage threshold at the BAT pin 60% state-of-charge voltage threshold at the BAT pin 80% state-of-charge voltage threshold at the BAT pin
Tolerance 25 10 30 30 30 30 30 30 30 30 30 30 30 30 30
Unit mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV SNS = 0V SNS = 0V SNS = 0V SNS = 0V SNS = 0V
Notes
* VCC * VCC * VCC * VCC * VCC * VCC * VCC * VCC
191
320
195
320
203
320
158
320
163
320
167
320
171
320
Fast or standard charge state; MULT pulled to VSS Fast or standard charge state; MULT pulled to VSS Fast or standard charge state; MULT pulled to VSS Fast or standard charge state; MULT pulled to VSS Discharge-before-charge state; MULT pulled to VSS; DIS = 1 Discharge-before-charge state; MULT pulled to VSS; DIS = 1 Discharge-before-charge state; MULT pulled to VSS; DIS = 1 Discharge-before-charge state; MULT pulled to VSS; DIS = 1
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bq2007
Recommended DC Operating Conditions (TA = 0 to +70C)
Symbol VCC VBAT VTS VTCO VCELL VTEMP VIH Tri-level input high Logic input low VIL Tri-level input low VOH VOL VOHCOM I OHCOM I CC I OH I OH I OL I OL I IZ Logic output high Logic output low COM output COM source Supply current DIS, LED1-2, SEGA-G source MOD DIS, LED1-2, SEGA-G sink MOD Tri-state inputs floating for Z state Input leakage IL Input leakage I IL I IH Logic input low current Logic input high current 50 -70 VCC - 0.8 VCC - 0.8 -40 -10 -5 10 5 -2.0 1 0.3 0.8 2.5 2.0 1 400 70 V V V V mA mA mA mA mA TM DIS, LED1-2, SEGA-G @ IOH = -10mA; MOD @IOH = -5mA DIS, LED1-2, SEGA-G @ IOL = 10mA; MOD @I OL = 5mA @I OHCOM = -40mA @VOHCOM = VCC - 0.8V No output load @VOH = VCC - 0.8V @VOH = VCC - 0.8V @VOL = VSS + 0.8V VCC - 0.3 0.8 V V TM DCMD, FAST, VSEL, INH Parameter Supply voltage Voltage on BAT pin Voltage on TS pin Temperature cutoff on TCO Battery voltage potential Voltage potential on TS Logic input high Minimum 4.5 0 0 0 0 0 2.0 Typical 5.0 Maximum 5.5 VCC VCC 0.5 * VCC VCC VCC Unit V V V V V V V Thermistor input Note 2 VBAT - VSNS VTS - VSNS DCMD, FAST, VSEL, INH 10% Notes
mA @ OL = VSS + 0.8V V A A A A A TM INH, VSEL, V = VSS to VCC DCMD, FAST, V = VSS to VCC TM, V = VSS to VSS + 0.3V TM, V = VCC - 0.3V to VCC
1SLUS076A - JULY 2000
12
bq2007
Impedance
Symbol RI Parameter DC input impedance: pins TS, BAT, SNS, TCO Soft-programmed pull-up resistor Float state external resistor Minimum 50 Typical Maximum Unit M MSEL, DSEL1, DSEL2, MULT, QDSEL; resistor value 10% tolerance TM Notes
RPROG
150
-
200
K
RFLT
-
5
-
M
Timing
Symbol dFCV t REG t PEND F COM F ALARM t PW
(TA = 0 to +70C; VCC 10%) Parameter Deviation of fast charge safety time-out MOD output regulation frequency Charge pending time-out Common LCD backplane frequency Alarm frequency output Pulse width for DCMD and INH pulse command Valid period for VCELL > VMCV Minimum 0.84 1 Typical 1.0 25 73 3500 Maximum 1.16 300 Unit kHz % Hz Notes At VCC = 10%, TA = 0 to 60C; see Table 3 Typical regulation range; VCC = 5.0V Ratio of fast charge time-out; see Table 4. LCD segment frame rate
kHz High tone s Signal valid time If VCELL VMCV for t MCV during charge or top-off, then a transition is recognized as a battery replacement.
t MCV
0.5
-
1
sec
Note:
Typical is at TA = 25C, VCC = 5.0V.
SLUS076A - JULY 20001
13
bq2007
24-Pin DIP Narrow (PN)
24-Pin PN (0.300" DIP)
Inches Dimension A A1 B B1 C D E E1 e G L S Min. 0.160 0.015 0.015 0.045 0.008 1.240 0.300 0.250 0.300 0.090 0.115 0.070 Max. 0.180 0.040 0.022 0.055 0.013 1.280 0.325 0.300 0.370 0.110 0.150 0.090 Millimeters Min. 4.06 0.38 0.38 1.14 0.20 31.50 7.62 6.35 7.62 2.29 2.92 1.78 Max. 4.57 1.02 0.56 1.40 0.33 32.51 8.26 7.62 9.40 2.79 3.81 2.29
S: 24-Pin S (0.300" SOIC)
24-Pin S (0.300" SOIC)
Inches Dimension
e D B
Millimeters Min. 2.41 0.10 0.33 0.20 15.24 7.37 1.14 10.03 0.51 Max. 2.67 0.30 0.51 0.33 15.62 7.75 1.40 10.54 1.02
Min. 0.095 0.004 0.013 0.008 0.600 0.290 0.045 0.395 0.020
Max. 0.105 0.012 0.020 0.013 0.615 0.305 0.055 0.415 0.040
A A1 B C D
E H A C
E e H L
.004 A1 L
1SLUS076A - JULY 2000
14
bq2007
Data Sheet Revision History
Change No. Page No. Description Nature of Change Was VSNSHI - (0.01 * VCC); is 0.04 * VCC
1
11
VSNSLO Rating
2
1
Added "Not Recommended for New Design" watermark.
Note:
Change 1 = Sept. 1996 changes from Dec. 1995. Change 2 = SLUS076A - JULY 2000 change from Sept. 1996
Ordering Information
bq2007 Temperature:
blank = Commercial (-20 to +70C) N = Industrial (-40 to +85C)*
Package Option:
PN = 24-pin narrow plastic DIP S = 24-pin SOIC
Device:
bq2007 Fast-Charge IC * Contact factory for availability.
1SLUS076A - JULY 2000
15
IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, patent infringement, and limitation of liability. TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI's standard warranty. Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements. Customers are responsible for their applications using TI components. In order to minimize risks associated with the customer's applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of TI covering or relating to any combination, machine, or process in which such semiconductor products or services might be or are used. TI's publication of information regarding any third party's products or services does not constitute TI's approval, warranty or endorsement thereof.
Copyright (c)
2000, Texas Instruments Incorporated

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