UNITRODE bq2007 Technical data

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Features

Fast charging and conditioning of

➤

NiCd and NiMH batteries

Precise charging independent

of battery pack number of cells

Discharge-before-charge on

demand

Pulse trickle charge

conditioning

Battery undervoltage and

overvoltage protection

Built-in 10-step voltage-based

➤

charge status monitoring

Charge status display options

include seven-segment monotonic bargraph 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

Audible alarm for charge

completion and fault conditions

Charge control flexibility

➤

Fast or Standard speed

charging

Top-off mode for NiMH

Charge rates from

to 2C

(30 minutes to 8 hours)

Charge termination by:

➤

Negative delta voltage (-∆V)

Peak voltage detect (PVD)

Maximum voltage

Maximum time

Maximum temperature

➤ High-efficiency switch-mode de-

sign

Ideal for small heat-sensitive

enclosures

➤ 24-pin,300-mil SOIC or DIP

bq2007

Fast-Charge IC

General Description

The bq2007 is a highly integrated monolithic CMOS IC designed to pro vide 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 moni tor supports up to a seven-segment bargraph or a single BCD digit dis play. The bargraph 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.

Pin Connections Pin Names

SEGC/ Display output segment C/ MSEL driver mode select

SEGC/MSEL

9/96 B

SEG SEG

LED LED

INH

COM

ALARM

VSEL FAST

DCMD

1 2

6 7 8 9 10 11 12

24-Pin Narrow DIP

or SOIC

24 23

21 20 19 18 17 16 15 14 13

PN200701.eps

SEGD/DSEL SEGE/DSEL

SEGF/MULT SEGG/QDSEL MOD V

SS DIS TS BAT SNS TCO

SEG

1 2

LED

INH

COM Common LED/LCD output

ALARM Audio alarm output

TM Timer mode select

VSEL Voltage termination select

FAST Fast charge rate select

DCMD

TCO Temperature cutoff

Display output segment B

Display output segment A

Charge status output 1

Charge status output 2

Charge inhibit input

Discharge command

SNS Sense resistor input

BAT Battery voltage

TS Temperature sense

DIS Discharge control

System ground

5.0V±10% power

MOD Modulation control

SEG

/ Display output segment G/

QDSEL charge status display select

SEG

/ Display output segment F/

MULT multi-cell pack select

SEG

/ Display output segment E/

DSEL

SEG DSEL

display select 2

/ Display output segment D/

display select 1

bq2007

The acceptable battery temperature range is set by an internal low-temperature threshold and an external high-temperature cutoff threshold. The absolute tem perature 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, the bq2007 enters the charge-pending state and attempts trickle-current condi tioning 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:

n Negative delta voltage (-

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 (V

CELL=VBAT-VSNS

) exceeds the VMCV value and ter minates 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.

The bq2007 indicates charge state status with an audio alarm output option and two dedicated output pins with pro grammable 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

SEG

MSEL

DSEL DSEL

MULT

QDSEL

LED LED

INH

Display output segments A–G

A–G

State-of-charge monitoring outputs. QDSEL input selects the bargraph or BCD digit dis play mode. See Table 3.

Display driver mode select

Soft-programmed input selects LED or LCD driver configuration at initialization. When MSEL is pulled up to V

, outputs SEG

LED interface levels; when MSEL is pulled down to V

Display mode select 1–2

–

, outputs SEG

are LCD levels.

A–G

Soft-programmed inputs control the LED

charger status display modes at initialization. See Table 2.

Fixed-cell pack select

Soft-programmed input is pulled up to V

when charging multi-cell packs and is pulled down to V

for charging packs with a fixed

number of cells.

State-of-charge display select

The QDSEL input controls the SEG

state-of-charge display modes. See Table 3.

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.

Charge inhibit input

When low, the bq2007 suspends all charge ac tions, 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.

A–G

are

1—2

A–G

bq2007

COM

ALARM

VSEL

FAST

DCMD

TCO

SNS

BAT

Common LCD/LED output

Common output for LCD/LED display SEG

initialization to allow reading of soft-programmed inputs DSEL MSEL, MULT, and QDSEL.

Audio output

Audio alarm output.

Timer mode select

TM is a three-level input that controls the set tings for charge control functions. See Table 5.

Voltage termination select

This input switches the voltage detect sensitivity. See Table 5.

Fast charge rate select

The FAST input switches between Fast and Standard charge rates. See Table 4.

Discharge command

The DCMD

before-charge function. A negative-going pulse initiates a discharge action. If DCMD is connected to VSS, automatic dischargebefore-charge is enabled. See Figure 3.

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.

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.

Battery voltage input

Battery voltage sense input referenced to SNS for the battery pack being charged. This resis tor divider network is connected between the positive and the negative terminals of the battery. See Figure 1.

. Output is high-impedance during

A—G

, DSEL2,

input controls the discharge-

DIS

MOD

Temperature sense input

Input referenced to SNS for battery tem perature monitoring negative temperature coefficient (NTC) thermistor.

Discharge control

DIS is a push-pull output that controls an external transistor to discharge the battery before charging.

Ground

VCCsupply 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 and control outputs are given for possible input 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 required discharge-before-charge operations. DCMD 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 time-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 the dedicated status outputs,LED

controls the discharge-before-charge

and LED2.

bq2007

Charge

Pending

(Pulse-Trickle)

Dis-

charge

(Optional)

DIS

MOD

or MOD

(Switching

Configuration)

(External

Regulation)

Mode 1, LED2 Status Output

Mode 1, LED1 Status Output

Mode 2, LED2 Status Output

Mode 2, LED1 Status Output

Mode 3, LED2 Status Output

Fast Charging

Top-Off

(Optional)

260 s

2080 s

260 s

2080 s

Pulse-Trickle

Note

260 s

Note

260 s

Mode 3, LED1 Status Output

Battery discharged to V temperature/voltage limits. (Discharge-before-charge not qualified by temperature.)

Low-voltage fault: Battery voltage less than V

Charge initiated. Battery outside temperature/voltage limits.

Note: See Table 4 for pulse-trickle period.

Figure 1. Example Charging Action Events

or battery within

EDV

for under-voltage time-out.

EDV

TD200701.eps

bq2007

Outputs LED

selected at initialization by the input pins DSEL DSEL

. The DSEL1and DSEL2input pins, when pulled

down to V simple two-LED system. LED status (i.e., charge pending and discharge) and LED

have three display modes that are

1–2

, are intended for implementation of a

indicates the precharge

and

indi

cates the charge status (i.e., charging and completion). DSEL

pulled up to VCCand DSEL2pulled down to V

mode is for implementation of a single tri-color LED such that discharge, charging, and completion each have a unique color. DSEL V

allows for fault status information to be displayed.

pulled down to VSSand DSEL2pulled up to

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 sig nal that is compatible with standard piezoelectric alarm elements. A valid battery insertion is indicated by a sin

gle high-tone beep of charge completion and fault conditions are indicated by a 9.5- to 15-second high-tone sequence of cal duration at a 2-second typical repetition rate.

Charge Action

State Conditions MOD Output DIS Output

Battery absent V

Charge initiation

Discharge-beforecharge

Charge pending

Fast charging

Standard charging

Charge complete

Top-off pending

Top-off charging

Trickle charging

Fault

Definitions: V

-second typical duration. The

Table 1. bq2007 Operational Summary

applied and V

applied or V

from≥V

DCMD

high-to-low transition or to VSSon charge

initiation and V

Charge initiation occurred and V

Charge pending complete and FAST = V

-∆V termination or V

-3mV/cell or maximum time-out or V VSEL = V

or V

VSEL = V

time-out not exceeded and V

Charge complete and top-off disabled or

Charge pending state and charge pending

= V

CELL

LTF

= 0.5*VCC.

BAT

- V

≤

TEMP

TCO

, charge complete and V

≤

TEMP

and charge complete and

CELL

top-off complete or pending

time-out (t

SNS;VMCV

= 0.8*VCC;V

-second typi-

CELL

to < V

MCV

< V

EDV

CELL

or V

CELL

< V

TEMP

TCO

PEND

or V

CELL

< V

MCV

) complete

TCO

TEMP

Charge Status Monitoring

The bq2007 charge status monitor may display the bat tery 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 V

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 V thresholds of V

20,V40,V60

is greater than the internal

BAT

,orV80, the respective 20%, 40%, 60%, or 80% display outputs are activated. The battery voltage directly indicates 20% charge increments, while the 10% charge increments use a timer that is a function of the charge safety timer.

When MULT is pulled down to V

exceeds V20during charging, the 20% charge indication

is activated and the timer begins counting for a period

equal to When the timer count is completed, the 30% charge

of the charge safety time-out period.

indication is activated. Should V the timer count completion, the charge status monitor activates the 30% and 40% indications. This technique

≥

MCV

drops

MCV

< V

MCV

≥

TEMP

< V

EDV

or PVD≥0 to

CELL

TEMP

< V

EDV

> V

TCO

LTF

> V

≥

Trickle charge per Table 4 Low

- Low

Low High

Trickle charge per Table 4 Low

and

Low if V high if V

MCV

LTF

Trickle charge per Table 4 Low

Activated per V

73ms of every 585ms Low

SNS

Trickle charge per Table 4 Low

= 0.262*VCCor 0.4*VCC;V

EDV

, the battery charge

exceed V40prior to

BAT

> 250mV;

< 200mV

> 250mV;

< 200mV

for

SNS

= VTS- V

TEMP

and when V

SNS

BAT

Low

;

bq2007

is used for all the odd percentage charge indications to assure a monotonic charge status display.

When MULT is pulled up to V

status monitor directly displays timer as a percentage of full charge. This method is rec

, the bq2007 charge

of the charge safety

ommended over the voltage-based method when charg ing 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 V

, the charge status monitor indicates the percentage of the bat tery voltage by comparing V

to the internal discharge

BAT

voltage reference thresholds. In BCD format, the dis charge thresholds V

80,V60,V40

, and V20correspond to a battery charge state indication of 90%, 70%, 50%, and 30%, respectively. In bargraph 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 bargraph format.

During discharge and when MULT is pulled up to V

the state-of-charge monitor BCD format displays the discharge condition, letter “d,” whereas the bargraph format has no indication.

Table 2. bq2007 Charge Status Display Summary

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 are a seven-segment monotonic bargraph or a sevensegment BCD single-digit format. When QDSEL is pulled down to V

segments of a single BCD digit display, and when QDSEL is pulled up to V ments of a bargraph display.

In the bargraph display mode, outputs SEG

tions for a three-segment to seven-segment bargraph dis

play. The three-segment charge status display uses out puts SEG

charge indications, respectively. The four-segment charge status display uses outputs SEG SEG

for 20%, 40%, 60%, and 80% indications,

respectively. The seven-segment charge status monitor uses all segments.

The BCD display mode drives pins SEG

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.

, pins SEG

drive the decoded seven

A–G

drive the seven seg

A–G

,SEGD, and SEGFfor 30%, 60%, and 90%

, SEGC, SEGD,and

A–G

allow op

with the

Mode Charge Action State LED

Battery absent 0000

Charge pending (temp. limit, low voltage) 0 Flashing 0 0

DSEL

= L

DSEL

(Mode 1)

= L

Discharge in progress 0110

Charging Flashing 0 0 0

Charge complete 1 0 0 High tone

Fault (low-voltage time-out) 0 0 0 High tone

Battery absent 0000

DSEL DSEL

(Mode 2)

= H = L

Discharge in progress, pending 1110

Charging 1000

Charge complete 0 1 0 High tone

Fault (low-voltage time-out) 0 0 0 High tone

Battery absent 0000

Charge pending (temp. limit, low voltage) 0 Flashing 0 0

DSEL

= L

DSEL

(Mode 3)

= H

Discharge in progress 0 Flashing 1 0

Charging Flashing 0 0 0

Charge complete 1 0 0 High tone

Fault (low-voltage time-out) 0 1 0 High tone

Note: 1 = on; 0 = off; L = pulled down to VSS; H = pulled up to VCC.

LED

DIS ALARM

bq2007

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 V

tialization. The output pin COM is the common anode connection for LED SEG

A–G

The LCD interface mode is enabled when the MSEL soft-programmed input pin is pulled to V

tion. An internal oscillator generates all the timing sig nals 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 SEG

pins is driven with the correct-phase AC signal

A–G

to activate the LCD segment. In bargraph or BCD mode, output pins SEG

interface to LED or LCD segments.

A–G

Table 3. bq2007 Charge Status Display Summary

Mode Display Indication SEG

20% charge 1000000

30% charge 1100000

40% charge 1110000

QDSEL = H

QDSEL = L

60% charge 1111000

80% charge 1111100

90% charge 1111110

Charge complete 1111111

0% charge—digit 0 1111110

10% charge—digit 1 0110000

20% charge—digit 2 1101101

30% charge—digit 3 1111001

40% charge—digit 4 0110011

50% charge—digit 5 1011011

60% charge—digit 6 1011111

70% charge—digit 7 1110010

80% charge—digit 8 1111111

90% charge—digit 9 1111011

Charge complete—letter F 1000111

Fault condition—letter E 1001111

Discharge—letter d 0111101

at ini

at initializa

Battery Voltage and Temperature Measurement

The battery voltage and temperature are monitored

within set minimum and maximum limits. When MULT is pulled up to V

by a resistive voltage divider that divides the terminal voltage between 0.262 ∗ V The bq2007 charges multi-cell battery packs from a mini

mum 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:

When MULT is pulled down to V

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 ∗ V

SEG

, battery voltage is sensed at the BAT pin

) and 0.8 ∗ VCC(V

1=−(

)

CC(VEDV

SEG

, tighter charge

) and 0.8 ∗ V

SEG

R1 N

R2133

SEG

CC(VEDV

SEG

MCV

Note: 1 = on; 0 = off; L = pulled down to VSS; H = pulled up to VCC.

bq2007

BAT

SNS

BAT Voltage Connection Thermistor Connection

NTC = negative temperature coefficient thermistor.

Figure 2. Voltage and Temperature Limit Measurement

). The bq2007 charges fixed-cell battery packs of N

MCV

cells. The battery voltage divider is set by the divider ratio equation:

R1 N R22

1=−()

Note: The resistor-divider network impedance should be above 200KΩto 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.

Temperature and Voltage Prequalifications

For charging to be initiated, the battery temperature must fall within predetermined acceptable limits. The voltage on the TS pin (V

temperature fault threshold (V temperature cutoff voltage (V ing to be initiated, V than V

. Since VTSdecreases as temperature increases, the

TCO

TCO threshold should be selected to be lower than 0.5 ∗ V 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 V

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 the low-voltage threshold (V

) is compared to an internal low-

) of (0.5 ∗ VCC) and the high

LTF

) on the TCO pin. For charg

TCO

must be less than V

). The battery voltage

EDV

and greater

LTF

bq2007

SNS

) is compared to the low-voltage threshold (V

CELL

and charge will be inhibited if V

N T C

SNS

FG200701.eps

CELL<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 V

by the rising edge of V

Discharge-before-charge (see Figure 3) is initiated auto matically on application of power or battery insertion when DCMD

is initiated by a negative-going pulse on the DCMD

MCV

to below V

. Power applied is detected

MCV

when a battery is inserted.

is connected to VSS. Discharge-on-demand

DCMD

bq2007

Always Discharge Discharge on

DCMD

bq2007

Command

Figure 3. Discharge-Before-Charge

EDV

)

Table 4. bq2007 Charge Action Control Summary

bq2007

FAST Input State

TM Input State

Float 640 (

Float 160 (

Time-out

Period

(min)

) 25% 2400 219Hz 109Hz

320 (

) 25% 1200 109Hz 55Hz

160 (

) 25% 600 55Hz 27Hz

) 100% 600 219Hz 109Hz

80 (C) 100% 300 109Hz 55Hz

40 (2C) 100% 150 55Hz 27Hz

regardless of charging activity. The DCMD pin is inter nally pulled up to V

; therefore, not connecting this pin

results in disabling the discharge-before-charge func tion. 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 (V

EDV

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

of the Fast charge rate, which is accomplished by dis

abling the regulator for a period of 286µs of every 1144µs (25% duty cycle). In addition to throttling back the charge current, time-out and hold-off safety time are increased ac cordingly. 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 Stan dard rate, it continues until terminated by any of the fol lowing conditions:

Negative delta voltage (-∆V)

Peak voltage detect (PVD)

Maximum temperature cutoff (TCO)

Maximum time-out (MTO)

Maximum cutoff voltage (MCV)

MOD Duty

Cycle

Voltage Termination Hold-off

To prevent early termination due to an initial false peak

Hold-off

period

(sec)

Trickle

Rep Rate

-∆V

Trickle

Rep Rate

PVD

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.

-∆V or PVD Termination

Table 5 summarizes the two modes for full-charge voltage termination detection. When V

negative delta voltage detection occurs when the voltage

seen on the BAT pin falls 12mV (typical) below the maximum sampled value. V voltage detect termination and the top-off charge state.

PVD termination occurs when the BAT pin voltage falls

SEL=VCC

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 V ∗ V

to 0.8 ∗ VCC.

for -∆V or PVD termination is from 0.262

BAT

Table 5. VSEL Configuration

VSEL

Detection

Method Top-Off

-∆V Disabled

PVD Enabled

SEL=VSS

selects peak

Pulse Trickle

Rate

bq2007

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 (V

), which is

compared to an internal high-temperature cutoff threshold of V

. The TCO reference level provides the

TCO

maximum limit for battery temperature during charging. MCV termination occurs when V

CELL>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.

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 V

SEL=VCC

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 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 286µs of a period specified in Table 4. This results in a trickle rate of for PVD and

when -∆V is enabled.

that of the

, the

Source

bq2007

MOD

SNS

Switch

Battery

Under Charge

SNS

Figure 4. Constant-Current Switching

Regulation

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 ∗ V

and 0.05 ∗ VCC. The nominal regulated current is

= 0.225V/R

REG

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 V

output is switched high to gate charge current through the inductor to the battery. When the SNS voltage is greater than V put 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 V

. See Figure 4.

SNS

(0.04 ∗ VCCnominal), the MOD

SNSLO

(0.05 ∗ VCCnominal), the MOD out

SNSHI

bq2007

Absolute Maximum Ratings

Symbol Parameter Minimum Maximum Unit Notes

OPR

STG

SOLDER

Note: Permanent device damage may occur if Absolute Maximum Ratings are exceeded. Functional opera

VCCrelative to V

DC voltage applied on any pin ex cluding V

relative to V

-0.3 +7.0 V

Operating ambient temperature -20 +70 °C Commercial

Storage temperature -40 +85 °C

Soldering temperature - +260 °C

tion should be limited to the Recommended DC Operating Conditions detailed in this data sheet. Expo sure to conditions beyond the operational limits for extended periods of time may affect device reliability.

DC Thresholds (T

= T

; VCC= 5V±10%)

OPR

Symbol Parameter Rating Tolerance Unit Notes

SNSHI

SNSLO

LTF

HTF

EDV

MCV

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 V

End-of-discharge voltage MULT is pulled down to V

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

0.05*V

0.04*V

0.5*V

TCO

0.262*V

0.4*V

0.8*V

187

320

191

320

195

320

203

320

158

320

163

320

167

320

171

320

mV SNS = 0V

Fast or standard charge state;

MULT pulled to V Fast or standard charge state;

MULT pulled to V Discharge-before-charge state;

MULT pulled to V

; DIS = 1

bq2007

Recommended DC Operating Conditions (T

= 0 to +70°C)

Symbol Parameter inimum Typical Maximum Unit Notes

BAT

TCO

CELL

TEMP

OHCOM

Supply voltage 4.5 5.0 5.5 V 10%

Voltage on BAT pin 0 - V

Voltage on TS pin 0 - V

Temperature cutoff on TCO 0 - 0.5*V

Battery voltage potential 0 - V

Voltage potential on TS 0 - V

V Thermistor input

V Note 2

BAT

VVTS- V

- V

SNS

Logic input high 2.0 - - V DCMD, FAST, VSEL, INH

Tri-level input high VCC- 0.3 - - V TM

Logic input low - - 0.8 V DCMD, FAST, VSEL, INH

Tri-level input low - - 0.3 V TM

Logic output high

- 0.8

--V

Logic output low - - 0.8 V

DIS, LED

-10mA; MOD @ I

DIS, LED

10mA; MOD @ I

COM output VCC- 0.8 - - V @ I

COM source -40 - - mA @ V

OHCOM

, SEG

1–2

, SEG

1–2

= -40mA

= VCC- 0.8V

Supply current - 1 2.5 mA No output load

DIS, LED

1–2

, SEG

source -10 - - mA @VOH= VCC- 0.8V

A–G

MOD -5 - - mA @VOH= VCC- 0.8V

DIS, LED

1–2

, SEG

sink 10 - - mA @VOL= VSS+ 0.8V

A–G

MOD 5 - - mA @VOL= VSS+ 0.8V

Tri-state inputs floating for Z state

Input leakage - -

-2.0 - 2.0

Input leakage 50 - 400

Logic input low current - - 70

Logic input high current -70 - -

A INH, VSEL, V = VSSto V

A DCMD, FAST, V = VSSto V

A TM, V = VSSto VSS+ 0.3V

A TM, V = VCC- 0.3V to V

A–G

= 5mA

@ IOH=

= -5mA

@ IOL=

Impedance

Symbol Parameter Minimum Typical Maximum Unit Notes

PROG

FLT

DC input impedance: pins TS, BAT, SNS, TCO

Soft-programmed pull-up resistor

Float state external resistor

50 - -

150 - 200

-5-

Ω

MSEL, DSEL

QDSEL; resistor value±10% tol

Ω

, DSEL2, MULT,

erance

Ω

bq2007

Timing (T

= 0 to +70°C; V

10%)

Symbol Parameter Minimum Typical Maximum Unit Notes

FCV

REG

PEND

COM

ALARM

MCV

Deviation of fast charge safety time-out

MOD output regulation frequency

0.84 1.0 1.16 -

- - 300 kHz

Charge pending time-out - 25 - %

Common LCD backplane frequency

- 73 - Hz LCD segment frame rate

Alarm frequency output - 3500 - kHz High tone

Pulse width for DCMD and INH

pulse command

Valid period for V V

MCV

CELL

1- -

0.5 - 1 sec

At VCC=±10%, TA= 0 to 60°C; see Table 3

Typical regulation range; V

= 5.0V

Ratio of fast charge time-out; see Table 4.

Signal valid time

CELL

≥

MCV

If V charge or top-off, then a transition is recognized as a battery replacement.

Note: Typical is at TA= 25°C, VCC= 5.0V.

for t

MCV

during

bq2007

24-Pin DIP Narrow (PN)

S: 24-Pin S(0.300" SOIC

24-Pin PN(0.300" DIP

Inches Millimeters

Dimension

A 0.160 0.180 4.06 4.57

A1 0.015 0.040 0.38 1.02

B 0.015 0.022 0.38 0.56

B1 0.045 0.055 1.14 1.40

C 0.008 0.013 0.20 0.33

D 1.240 1.280 31.50 32.51

E 0.300 0.325 7.62 8.26

E1 0.250 0.300 6.35 7.62

e 0.300 0.370 7.62 9.40

G 0.090 0.110 2.29 2.79

L 0.115 0.150 2.92 3.81

S 0.070 0.090 1.78 2.29

Min. Max. Min. Max.

)

24-Pin S(0.300" SOIC

Inches Millimeters

Dimension

A 0.095 0.105 2.41 2.67

A1 0.004 0.012 0.10 0.30

B 0.013 0.020 0.33 0.51

C 0.008 0.013 0.20 0.33

D 0.600 0.615 15.24 15.62

E 0.290 0.305 7.37 7.75

e 0.045 0.055 1.14 1.40

H 0.395 0.415 10.03 10.54

L 0.020 0.040 0.51 1.02

Min. Max. Min. Max.

)

.004

Data Sheet Revision History

Change No. Page No. Description Nature of Change

bq2007

111V

Note: Change 1 = Sept. 1996 B changes from Dec. 1995.

SNSLO

Rating

Ordering Information

bq2007 -

Temperature:

blank = Commercial (-20 to +70°C) N = Industrial (-40 to +85°C)*

Package Option:

PN = 24-pin narrow plastic DIP S = 24-pin SOIC

Device:

bq2007 Fast-Charge IC

Was V

SNSHI

is 0.04 * V

- (0.01 * VCC);

* Contact factory for availability.

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UNITRODE bq2007 Technical data

Specifications and Main Features

Frequently Asked Questions

User Manual