TI BQ2031 Lead-acid fast-charge ic Datasheet

bq2031
Lead-Acid Fast-Charge IC
Features
-
➤ Conforms to battery manufacturers' charge recommendations for
cyclic and float charge
Ideal for high-efficiency
switch-mode power conversion
-
Configurable for linear or
gated current use
➤ Pin-selectable charge algorithms
-
Two-Step Voltage with
temperature-compensated
constant-voltage maintenance
-
Two-Step Current with
constant-rate pulsed current
maintenance
-
Pulsed Current: hysteretic,
on-demand pulsed current
➤ Pin-selectable charge termination
by maximum voltage,∆2V, minimum current, and maximum
time
➤ Pre-charge qualification detects
shorted, opened, or damaged cells
and conditions battery
➤ Direct LED control outputs display charge status and fault conditions
General Description
The bq2031 Lead-Acid Fast Charge
IC is designed to optimize charging
of lead-acid chemistry batteries. A
flexible pulse-width modulation
regulator allows the bq2031 to control constant-voltage, constantcurrent, or pulsed-current charging.
The regulator frequency is set by an
external capacitor for design flexibility. The switch-mode design keeps
power dissipation to a minimum for
high charge current applications.
➤ Pulse-width modulation control
A charge cycle begins when power is
applied or the battery is replaced.
For safety, charging is inhibited until the battery voltage is within configured limits. If the battery voltage is
less than the low-voltage threshold,
the bq2031 provides trickle-current
Pin Connections
Pin Names
➤ Charging continuously qualified by
temperature and voltage limits
➤ Internal temperature-compensated voltage reference
TMTO
Time-out timebase input
charging until the voltage rises into
the allowed range or an internal
timer runs out and places the
bq2031 in a Fault condition. This
procedure prevents high-current
charging of cells that are possibly
damaged or reversed. Charging is
inhibited anytime the temperature
of the battery is outside the configurable, allowed range. All voltage
t h r es h old s a r e t em p er a t u r e compensated.
The bq2031 terminates fast (bulk)
charging based on the following:
■
Maximum voltage
■
Second difference of cell voltage
(∆2V)
■
Minimum current (in constantvoltage charging)
■
Maximum time-out (MTO)
After bulk charging, the bq2031 provides temperature-compensated
maintenance (float) charging to
maintain battery capacity.
LED3/
QSEL
Charge status output 3/
Charge algorithm select
input 1
TMTO
1
16
LED2/DSEL
FLOAT
State control output
FLOAT
2
15
LED1/TSEL
BAT
Battery voltage input
COM
Common LED output
BAT
3
14
MOD
VCOMP
Voltage loop comp input
VSS
System ground
VCOMP
4
13
VCC
ICOMP
Current loop comp input
VCC
5.0V± 10% power
ICOMP
5
12
VSS
IGSEL
6
11
COM
IGSEL
Current gain select input
MOD
Modulation control
output
SNS
7
10
LED3/QSEL
SNS
Sense resistor input
TS
8
9
TPWM
TS
Temperature sense input
LED1/
TSEL
Charge status output 1/
Charge algorithm select
input 2
TPWM
Regulator timebase input
LED2/
DSEL
Charge status output 2/
Display select input
16-Pin Narrow
DIP or SOIC
PN203101.eps
SLUS156–JUNE 1999 E
1
bq2031
TPWM
Pin Descriptions
TMTO
This input uses an external timing capacitor
to ground the pulse-width modulation
(PWM) frequency. See equation 9.
Time-out timebase input
This input sets the maximum charge time.
The resistor and capacitor values are determined using equation 6. Figure 9 shows the
resistor/capacitor connection.
FLOAT
COM
QSEL
MOD
Voltage loop compensation input
LED1–3
Current gain select input
DSEL
TSEL
Termination select input
With QSEL, selects the charge algorithm.
See Table 1.
Charging current sense input
VCC
Battery current is sensed via the voltage developed on this pin by an external sense resistor, RSNS, connected in series with the low
side of the battery. See equation 8.
TS
Display select input
This three-level input controls the LED1–3
charge display modes. See Table 2.
Current loop compensation input
This input uses an external C or R-C network for current loop stability.
SNS
Charger display status 1–3 outputs
These charger status output drivers are for
the direct drive of the LED display. Display
modes are shown in Table 2. These outputs are
tri-stated during initialization so that QSEL,
TSEL, and DSEL can be read.
This three-state input is used to set IMIN for
fast charge termination in the Two-Step
Voltage algorithm and for maintenance current regulation in the Two-Step Current algorithm. See Tables 3 and 4.
ICOMP
Current-switching control output
MOD is a pulse-width modulated push/pull
output that is used to control the charging
current to the battery. MOD switches high
to enable current flow and low to inhibit current flow.
This input uses an external C or R-C network for voltage loop stability.
IGSEL
Charge regulation select input
With TSEL, selects the charge algorithm.
See Table 1.
Battery voltage input
BAT is the battery voltage sense input. This potential is generally developed using a highimpedance resistor divider network connected
between the positive and the negative terminals
of the battery. See Figure 6 and equation 2.
VCOMP
Common LED output
Common output for LED1–3. This output is
in a high-impedance state during initialization to read program inputs on TSEL,
QSEL, and DSEL.
Float state control output
This open-drain output uses an external resistor divider network to control the BAT input voltage threshold (VFLT) for the float
charge regulation. See Figure 1.
BAT
Regulation timebase input
VCC supply
5.0V, ± 10% power
VSS
Temperature sense input
Ground
Functional Description
This input is for an external battery temperature monitoring thermistor or probe. An
external resistor divider network sets the
lower and upper temperature thresholds.
See Figures 7 and 8 and equations 4 and 5.
The bq2031 functional operation is described in terms of:
2
n
Charge algorithms
n
Charge qualification
n
Charge status display
n
Voltage and current monitoring
n
Temperature monitoring
bq2031
n
Fast charge termination
n
Maintenance charging
n
Charge regulation
Chip On
VCC
4.5V
Charge Algorithms
Temperature
Checks On
Three charge algorithms are available in the bq2031:
n
Present
VLCO < VCELL < VHCO
Two-Step Voltage
Temperature
in Range
Test 1
ISNS < ICOND
n
Two-Step Current
n
Pulsed Current
Temperature Out
of Range or
Thermistor Absent
Voltage
Regulation
@ VFLT +
0.25V
Absent
VCELL < VLCO or
VCELL > VHCO
Battery
Status?
Fail:
t = tQT1 or
VCELL > VHCO
Fault
LED3 = 1
MOD = 0
VCELL
VCELL
PASS: ISNS > ICOND
The state transitions for these algorithms are described
in Table 1 and are shown graphically in Figures 2
through 4. The user selects a charge algorithm by configuring pins QSEL and TSEL.
Test 2
Fail:
t = tQT2 or
VCELL < VLCO or
VCELL > VHCO
VCELL < VMIN
Current
Regulation
@ICOND
VLCO or
VHCO
Charge
Pending
LED3 Flash
MOD = 0
PASS: VCELL > VMIN
Charge Qualification
VCELL < VLCO or
VCELL > VHCO
Bulk
Charge
The bq2031 starts a charge cycle when power is applied
while a battery is present or when a battery is inserted.
Figure 1 shows the state diagram for pre-charge qualification and temperature monitoring. The bq2031 first
checks that the battery temperature is within the allowed, user-configurable range. If the temperature is
out-of-range (or the thermistor is missing), the bq2031
enters the Charge Pending state and waits until the battery temperature is within the allowed range. Charge
Pending is annunciated by LED3 flashing.
Temperature Out
of Range or
Thermistor Absent
Fast
Charge
Temperature In
Range, Return
to Original State
Termination
VCELL < VMIN
FG203101.eps
Figure 1. Cycle Start/Battery
Qualification State Diagram
Table 1. bq2031 Charging Algorithms
Algorithm/State
QSEL
TSEL
Conditions
MOD Output
Two-Step Voltage
Fast charge, phase 1
Fast charge, phase 2
Primary termination
Maintenance
Two-Step Current
Fast charge
Primary termination
Maintenance
Pulsed Current
Fast charge
Primary termination
L
H/LNote 1
-
Current regulation
Voltage regulation
Maintenance
Notes:
H
L
H
H
while VBAT < VBLK, ISNS = IMAX
while ISNS > IMIN, VBAT = VBLK
ISNS = IMIN
VBAT = VFLT
while VBAT < VBLK, ISNS = IMAX
VBAT = VBLK or ∆2V < -8mVNote 2
ISNS pulsed to average IFLT
while VBAT < VBLK, ISNS = IMAX
VBAT = VBLK
ISNS = IMAX after VBAT = VFLT;
ISNS = 0 after VBAT = VBLK
Voltage regulation
Current regulation
Fixed pulse current
Current regulation
Hysteretic pulsed
current
1. May be high or low, but do not float.
2. A Unitrode proprietary algorithm for accumulating successive differences between samples of VBAT.
3
bq2031
test 2 before the bq2031 recognizes its “pass” criterion. If this
second test passes, the bq2031 begins fast (bulk) charging.
Thermal monitoring continues throughout the charge
cycle, and the bq2031 enters the Charge Pending state
anytime the temperature is out of range. (There is one
exception; if the bq2031 is in the Fault state—see below—the out-of-range temperature is not recognized until the bq2031 leaves the Fault state.) All timers are
suspended (but not reset) while the bq2031 is in Charge
Pending. When the temperature comes back into range,
the bq2031 returns to the point in the charge cycle
where the out-of-range temperature was detected.
Once in the Fault state, the bq2031 waits until VCC is cycled or a battery insertion is detected. It then starts a new
charge cycle and begins the qualification process again.
Charge Status Display
Charge status is annunciated by the LED driver outputs
LED1–LED3. Three display modes are available in the bq2031;
the user selects a display mode by configuring pin DSEL. Table
2 shows the three modes and their programming pins.
When the temperature is valid, the bq2031 performs two
tests on the battery. In test 1, the bq2031 regulates a voltage
of VFLT + 0.25V across the battery and observes ISNS. If ISNS
does not rise to at least ICOND within a time-out period (e.g.,
the cell has failed open), the bq2031 enters the Fault state. If
test 1 passes, the bq2031 then regulates current to ICOND (=
IMAX/5) and watches VCELL (= VBAT - VSNS). If VCELL does
not rise to at least VFLT within a time-out period (e.g., the cell
has failed short), again the bq2031 enters the Fault state. A
hold-off period is enforced at the beginning of qualification
The bq2031 does not distinguish between an over-voltage
fault and a “battery absent” condition. The bq2031 enters
the Fault state, annunciated by turning on LED3, whenever the battery is absent. The bq2031, therefore, gives an
indication that the charger is on even when no battery is
in place to be charged.
Table 2. bq2031 Display Output Summary
Mode
DSEL = 0
(Mode 1)
DSEL = 1
(Mode 2)
DSEL = Float
(Mode 3)
Notes:
Charge Action State
LED1
LED2
LED3
Battery absent or over-voltage fault
Low
Low
High
Pre-charge qualification
Flash
Low
Low
Fast charging
High
Low
Low
Maintenance charging
Low
High
Low
Charge pending (temperature out of range)
X
X
Flash
Charging fault
X
X
High
Battery absent or over-voltage fault
Low
Low
High
Pre-charge qualification
High
High
Low
Fast charge
Low
High
Low
Maintenance charging
High
Low
Low
Charge pending (temperature out of range)
X
X
Flash
Charging fault
X
X
High
Battery absent or over-voltage fault
Low
Low
High
Pre-charge qualification
Flash
Flash
Low
Fast charge: current regulation
Low
High
Low
Fast charge: voltage regulation
High
High
Low
Maintenance charging
High
Low
Low
Charge pending (temperature out of range)
X
X
Flash
Charging fault
X
X
High
1 = VCC; 0 = VSS; X = LED state when fault occurred; Flash = 1 6 s low, 1 6 s high.
In the Pulsed Current algorithm, the bq2031 annunciates maintenance when charging current is off and
fast charge whenever charging current is on.
4
VBLK
VFLT
Voltage
Maintenance
Fast Charge
Phase 1
VMIN
Phase 2
ICOND
Voltage
Current
IMAX
Qualification
bq2031
Current
IMIN
IFLT
Time
VBLK
Current
VFLT
Voltage
VMIN
Maintenance
ICOND
Fast Charge
Voltage
Current
IMAX
Qualification
Figure 2. Two-Step Voltage Algorithm
Time
ICOND
Maintenance
Current
VBLK
VFLT
Voltage
VMIN
Voltage
Current
IMAX
Qualification
Figure 3. Two-Step Current Algorithm
Fast Charge
Time
Figure 4. Pulsed Current Algorithm
5
bq2031
Configuring Algorithm and Display
Modes
VCC
QSEL/LED 3 , DSEL/LED 2 , and TSEL/LED 1 are bidirectional pins with two functions; they are LED driver
pins as outputs and programming pins for the bq2031 as
inputs. The selection of pull-up, pull-down, or no pull resistor programs the charging algorithm on QSEL and
TSEL per Table 1 and the display mode on DSEL per
Table 2. The bq2031 latches the program states when
any of the following events occurs:
1.
VCC rises to a valid level.
2.
The bq2031 leaves the Fault state.
3.
The bq2031 detects battery insertion.
BAT +
FLOAT
BAT
13
RB1
2
3
RB3
VCC
12
RB2
VSS
SNS
bq2031
The LEDs go blank for approximately 750ms (typical)
while new programming data is latched.
BAT -
7
RSNS
VSS
For example, Figure 5 shows the bq2031 configured for
the Pulsed Current algorithm and display mode 2.
FG203102.eps
Voltage and Current Monitoring
Figure 6. Configuring the Battery Divider
The bq2031 monitors battery pack voltage at the BAT
pin. A voltage divider between the positive and negative
terminals of the battery pack is used to present a scaled
battery pack voltage to the BAT pin and an appropriate
value for regulation of float (maintenance) voltage to the
FLOAT pin. The bq2031 also uses the voltage across a
sense resistor (RSNS) between the negative terminal
of the battery pack and ground to monitor current.
See Figure 6 for the configuration of this network.
VCC
10K
10K
16
LED2/DSEL
1K
15
LED1/TSEL
1K
13
VCC
12
VSS
11
COM
10
LED3/QSEL
bq2031
1K
10K
VSS
FG203103.eps
Figure 5. Configuring Charging Algorithm and Display Mode
6
bq2031
The user must include a pull-up resistor from the positive terminal of the battery stack to VDC (and a diode to
prevent battery discharge through the power supply
when the supply is turned off) in order to detect battery
removal during periods of voltage regulation. Voltage
regulation occurs in pre-charge qualification test 1 prior
to all of the fast charge algorithms, and in phase 2 of the
Two-Step Voltage fast charge algorithm.
The resistor values are calculated from the following:
Equation 1
RB1 (N ∗ VFLT )
=
−1
RB2
2.2V
Equation 2
N ∗ VBLK
RB1 RB1
)−1
+
=(
RB2 RB3
2.2
Temperature Monitoring
The bq2031 monitors temperature by examining the
voltage presented between the TS and SNS pins (VTEMP)
by a resistor network that includes a Negative Temperature Coefficient (NTC) thermistor. Resistance variations
around that value are interpreted as being proportional
to the battery temperature (see Figure 7).
Equation 3
I MAX =
0.250 V
R SNS
where:
n
N = Number of cells
The temperature thresholds used by the bq2031 and
their corresponding TS pin voltage are:
n
VFLT = Desired float voltage
n
n
VBLK = Desired bulk charging voltage
n
IMAX = Desired maximum charge current
n
These parameters are typically specified by the battery
manufacturer. The total resistance presented across the
battery pack by RB1 + RB2 should be between 150kΩ
and 1MΩ. The minimum value ensures that the divider
network does not drain the battery excessively when the
power source is disconnected. Exceeding the maximum
value increases the noise susceptibility of the BAT pin.
TCO—Temperature cutoff—Higher limit of the temperature range in which charging is allowed. VTCO =
0.4 * VCC
HTF—High-temperature fault—Threshold to
which temperature must drop after temperature
cutoff is exceeded before charging can begin again.
VHTF = 0.44 * V CC
VCC
Colder
An empirical procedure for setting the values in the resistor network is as follows:
2.
Determine RB1 from equation 1 given VFLT
3.
Determine RB3 from equation 2 given VBLK
4.
Calculate RSNS from equation 3 given IMAX
VLTF = 0.6V
Voltage
Set RB2 to 49.9 kΩ. (for 3 to 18 series cells)
Battery Insertion and Removal
The bq2031 uses VBAT to detect the presence or absence
of a battery. The bq2031 determines that a battery is
present when VBAT is between the High-Voltage Cutoff
(VHCO = 0.6 * VCC) and the Low-Voltage Cutoff (VLCO =
0.8V). When VBAT is outside this range, the bq2031 determines that no battery is present and transitions to
the Fault state. Transitions into and out of the range
between VLCO and VHCO are treated as battery insertions and removals, respectively. Besides being used to
detect battery insertion, the VHCO limit implicitly serves
as an over-voltage charge termination, because exceeding this limit causes the bq2031 to believe that the battery has been removed.
VHTF = 0.44V
VTCO = 0.4V
VSS
LTF
HTF
TCO
Hotter
FG203104.eps
Figure 7. Voltage Equivalent
of Temperature Thresholds
7
Temperature
1.
bq2031
n
LTF—Low-temperature fault—Lower limit of the
temperature range in which charging is allowed. VLTF
= 0.6 * VCC
VCC
A resistor-divider network must be implemented that
presents the defined voltage levels to the TS pin at the
desired temperatures (see Figure 8).
RT1
bq2031
The equations for determining RT1 and RT2 are:
13
Equation 4
NTC
Thermistor
VCC
0.6 ∗ VCC =
12
(VCC − 0.250 V )
RT1 ∗ (RT2 + R LTF )
1+
(RT2 ∗ R LTF )
VSS
RT2
t
SNS
Equation 5
TS
0.44 =
RT
7
8
BAT RSNS
1
RT1 ∗ (RT2 + R HTF )
1+
(RT2 ∗ R HTF )
VSS
FG203105.eps
where:
n
RLTF = thermistor resistance at LTF
n
RHTF = thermistor resistance at HTF
Figure 8. Configuring
Temperature Sensing
TCO is determined by the values of RT1 and RT2. 1%
resistors are recommended.
Disabling Temperature Sensing
Minimum Current
Temperature sensing can be disabled by removing RT
and using a 100kΩ resistor for RT1 and RT2.
Fast charge terminates when the charging current drops
below a minimum current threshold programmed by the
value of IGSEL (see Table 3). This is used by the TwoStep Voltage algorithm.
Temperature Compensation
The internal voltage reference used by the bq2031 for all
voltage threshold determinations is compensated for
temperature. The temperature coefficient is -3.9mV/°C,
normalized to 25°C. Voltage thresholds in the bq2031
vary by this proportion as ambient conditions change.
Table 3. IMIN Termination Thresholds
Fast-Charge Termination
Fast-charge termination criteria are programmed with
the fast charge algorithm per Table 1. Note that not all
criteria are applied in all algorithms.
8
IGSEL
IMIN
0
IMAX/10
1
IMAX/20
Z
IMAX/30
bq2031
Second Difference (∆2V)
VCC
Second difference is a Unitrode proprietary algorithm
that accumulates the difference between successive samples of VBAT. The bq2031 takes a sample and makes a
termination decision at a frequency equal to 0.008 *
tMTO. Fast charge terminates when the accumulated difference is ≤ -8mV. Second difference is used only in the
Two-Step Current algorithm, and is subject to a hold-off
period (see below).
R
1
TM
C
VCC
VSS
13
12
Maximum Voltage
Fast charge terminates when VCELL ≥ VBLK. VBLK is set
per equation 2. Maximum voltage is used for fast charge
termination in the Two-Step Current and Pulsed Current algorithms, and for transition from phase 1 to
phase 2 in the Two-Step Voltage algorithm. This criterion is subject to a hold-off period.
bq2031
VSS
FG203112.eps
Hold-off Periods
Figure 9. R-C Network for Setting MTO
Maximum V and ∆2V termination criteria are subject
to a hold-off period at the start of fast charge equal to
0.15 * tMTO. During this time, these termination criteria
are ignored.
Maintenance Charging
Three algorithms are used in maintenance charging:
Maximum Time-Out
Fast charge terminates if the programmed MTO time is
reached without some other termination shutting off
fast charge. MTO is programmed from 1 to 24 hours by
an R-C network on TMTO (see Figure 9) per the equation:
n
Two-Step Voltage algorithm
n
Two-Step Current algorithm
n
Pulsed Current algorithm
Two-Step Voltage Algorithm
Equation 6
In the Two-Step Voltage algorithm, the bq2031 provides
charge maintenance by regulating charging voltage to
VFLT. Charge current during maintenance is limited to
ICOND.
tMTO = 0.5 * R * C
where R is in kΩ, C is in µF, and tMTO is in hours. Typically, the maximum value for C of 0.1µF is used.
Two-Step Current Algorithm
Fast-charge termination by MTO is a Fault only in the
Pulsed Current algorithm; the bq2031 enters the Fault
state and waits for a new battery insertion, at which
time it begins a new charge cycle. In the Two-Step Voltage and Two-Step Current algorithms, the bq2031 transitions to the maintenance phase on MTO time-out.
Maintenance charging in the Two-Step Current Algorithm is implemented by varying the period (TP) of a
fixed current (ICOND = IMAX/5) and duration (0.2 seconds) pulse to achieve the configured average maintenance current value. See Figure 10.
The MTO timer starts at the beginning of fast charge. In
the Two-Step Voltage algorithm, it is cleared and restarted when the bq2031 transitions from phase 1 (current regulation) to phase 2 (voltage regulation). The
MTO timer is suspended (but not reset) during the outof-range temperature (Charge Pending) state.
Maintenance current can be calculated by:
Equation 7
Maintenance current =
((0.2) ∗ I COND ) ((0.04) ∗ I MAX )
=
TP
TP
where TP is the period of the waveform in seconds.
Table 4 gives the values of P programmed by IGSEL.
9
bq2031
Voltage at the SNS pin is determined by the value of resistor RSNS, so nominal regulated current is set by:
Table 4. Fixed-Pulse Period by IGSEL
IGSEL
TP (sec.)
L
0.4
H
0.8
Z
1.6
Equation 8
IMAX = 0.250V/RSNS
The switching frequency of the MOD output is determined by an external capacitor (CPWM) between the
pin TPWM and ground, per the following:
Equation 9
Pulsed Current Algorithm
FPWM = 0.1/CPWM
In the Pulsed Current algorithm, charging current is
turned off after the initial fast charge termination until
VCELL falls to VFLT. Full fast charge current (IMAX) is
then re-enabled to the battery until VCELL rises to VBLK.
This cycle repeats indefinitely.
where C is in µF and F is in kHz. A typical switching
rate is 100kHz, implying CPWM = 0.001µF. MOD pulse
width is modulated between 0 and 80% of the switching
period.
To prevent oscillation in the voltage and current control
loops, frequency compensation networks (C or R-C) are
typically required on the VCOMP and ICOMP pins (respectively) to add poles and zeros to the loop control equations.
A software program, “CNFG2031,” is available to assist in
configuring these networks for buck type regulators. For
more detail on the control loops in buck topology, see the
application note, “Switch-Mode Power Conversion Using
the bq2031.” For assistance with other power supply topologies, contact the factory.
Charge Regulation
The bq2031 controls charging through pulse-width modulation of the MOD output pin, supporting both constantcurrent and constant-voltage regulation. Charge current
is monitored by the voltage at the SNS pin, and charge
voltage by voltage at the BAT pin. These voltages are
compared to an internal temperature-compensated reference, and the MOD output modulated to maintain the desired value.
ICOND
IGSEL = L
Ave. Current
0
TP = 0.4 Sec
0.2 Sec
ICOND
IGSEL = H
Ave. Current
0
TP = 0.8 Sec
ICOND
IGSEL = Z
Ave. Current
0
TP = 1.6 Sec
TD203101.eps
Figure 10. Implementation of Fixed-Pulse Maintenance Charge
10
bq2031
Absolute Maximum Ratings
Symbol
Parameter
Minimum
Maximum
Unit
VCC
VCC relative to VSS
-0.3
+7.0
V
VT
DC voltage applied on any pin excluding VCC relative to VSS
-0.3
+7.0
V
TOPR
Operating ambient temperature
-20
+70
°C
TSTG
Storage temperature
-55
+125
°C
TSOLDER
Soldering temperature
-
+260
°C
TBIAS
Temperature under bias
-40
+85
°C
Note:
Commercial
10 s. max.
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.
DC Thresholds
Symbol
Notes
(TA = TOPR; VCC = 5V ± 10%)
Parameter
Rating
Unit
Tolerance
Internal reference voltage
2.20
V
1%
Temperature coefficient
-3.9
mV/°C
10%
VLTF
TS maximum threshold
0.6 * VCC
V
± 0.03V
Low-temperature fault
VHTF
TS hysteresis threshold
0.44 * VCC
V
± 0.03V
High-temperature fault
VTCO
TS minimum threshold
0.4 * VCC
V
± 0.03V
Temperature cutoff
VHCO
High cutoff voltage
0.60 * VCC
V
± 0.03V
VMIN
Under-voltage threshold at BAT
0.34 * VCC
V
± 0.03V
VLCO
Low cutoff voltage
0.8
V
± 0.03V
0.250
V
10%
VSNS
IMAX
Current sense at SNS
0.05
V
10%
ICOND
VREF
11
Notes
TA = 25°C
bq2031
Recommended DC Operating Conditions (TA = TOPR)
Symbol
Parameter
Minimum
Typical Maximum
Unit
Notes
VCC
Supply voltage
4.5
5.0
5.5
V
VTEMP
TS voltage potential
0
-
VCC
V
VCELL
Battery voltage potential
0
-
VCC
V
ICC
Supply current
-
2
4
mA
Outputs unloaded
DSEL tri-state open detection
-2
-
Note 2
IGSEL tri-state open detection
-2
IIZ
VIH
VIL
VOH
VOL
IOH
IOL
IIL
IIH
IL
Notes:
Logic input high
Logic input low
VCC-1.0
-
VTS - VSNS
VBAT - VSNS
2
µA
2
µA
-
V
QSEL,TSEL
VCC-0.3
-
-
V
DSEL, IGSEL
-
-
VSS+1.0
V
QSEL,TSEL
-
-
VSS+0.3
V
DSEL, IGSEL
LED1, LED2, LED3, output high
VCC-0.8
-
-
V
IOH ≤ 10mA
MOD output high
VCC-0.8
-
-
V
IOH ≤ 10mA
LED1, LED2, LED3, output low
-
-
VSS+0.8V
V
IOL ≤ 10mA
MOD output low
-
-
VSS+0.8V
V
IOL ≤ 10mA
FLOAT output low
-
-
VSS+0.8V
V
IOL ≤ 5mA, Note 3
COM output low
-
-
VSS+0.5
V
IOL ≤ 30mA
LED1, LED2, LED3, source
-10
-
-
mA
VOH =VCC-0.5V
MOD source
-5.0
-
-
mA
VOH =VCC-0.5V
LED1, LED2, LED3, sink
10
-
-
mA
VOL = VSS+0.5V
MOD sink
5
-
-
mA
VOL = VSS+0.8V
FLOAT sink
5
-
-
mA
VOL = VSS+0.8V, Note 3
COM sink
30
-
-
mA
VOL = VSS+0.5V
-
-
+30
µA
V = VSS to VSS+ 0.3V, Note 2
DSEL logic input low source
IGSEL logic input low source
-
-
+70
µA
V = VSS to VSS+ 0.3V
DSEL logic input high source
-30
-
-
µA
V = VCC - 0.3V to VCC
IGSEL logic input high source
-70
-
-
µA
V = VCC - 0.3V to VCC
-
-
±1
µA
QSEL, TSEL, Note 2
Input leakage
1. All voltages relative to VSS except where noted.
2. Conditions during initialization after VCC applied.
3. SNS = 0V.
12
bq2031
Impedance
Symbol
Parameter
Minimum
Typical
Maximum
Unit
Notes
RBATZ
BAT pin input impedance
50
-
-
MΩ
RSNSZ
SNS pin input impedance
50
-
-
MΩ
RTSZ
TS pin input impedance
50
-
-
MΩ
RPROG1
Soft-programmed pull-up or pull-down
resistor value (for programming)
-
-
10
kΩ
DSEL, TSEL, and
QSEL
RPROG2
Pull-up or pull-down resistor value
-
-
3
kΩ
IGSEL
RMTO
Charge timer resistor
20
-
480
kΩ
Timing
(TA = TOPR; VCC = 5V ± 10%)
Symbol
Parameter
Minimum
Typical
Maximum
Unit
Notes
See Figure 9
tMTO
Charge time-out range
1
-
24
hours
tQT1
Pre-charge qual test 1 time-out period
-
0.02tMTO
-
-
tQT2
Pre-charge qual test 2 time-out period
-
0.16tMTO
-
-
2
tDV
∆ V termination sample frequency
-
0.008tMTO
-
-
tH01
Pre-charge qual test 2 hold-off period
-
0.002tMTO
-
-
tH02
Bulk charge hold-off period
-
0.015tMTO
-
FPWM
PWM regulator frequency range
-
100
kHz
See Equation 9
Capacitance
Symbol
Parameter
Minimum
Typical
Maximum
Unit
CMTO
Charge timer capacitor
-
0.1
0.1
µF
CPWM
PWM R-C capacitance
-
0.001
-
µF
13
bq2031
16-Pin DIP Narrow (PN)
16-Pin PN (0.300" DIP)
Inches
Dimension
Millimeters
Min.
Max.
Min.
Max.
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
0.055
0.065
1.40
1.65
C
0.008
0.013
0.20
0.33
D
0.740
0.770
18.80
19.56
E
0.300
0.325
7.62
8.26
E1
0.230
0.280
5.84
7.11
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
0.020
0.040
0.51
1.02
16-Pin SOIC Narrow (SN)
16-Pin SN (0.150" SOIC)
Inches
D
e
Dimension
B
E
H
A
C
A1
.004
L
14
Millimeters
Min.
Max.
Min.
Max.
A
0.060
0.070
1.52
1.78
A1
0.004
0.010
0.10
0.25
B
0.013
0.020
0.33
0.51
C
0.007
0.010
0.18
0.25
D
0.385
0.400
9.78
10.16
E
0.150
0.160
3.81
4.06
e
0.045
0.055
1.14
1.40
H
0.225
0.245
5.72
6.22
L
0.015
0.035
0.38
0.89
bq2031
Data Sheet Revision History
Change No.
Page No.
1
Description
Nature of Change
Descriptions
Clarified and consolidated
1
Renamed
Dual-Level Constant Current Mode to Two-Step Current Mode
VMCV to VHCO
VINT to VLCO
tUV1 to tQT1
tUV2 to tQT2
1
Consolidation
Tables 1 and 2
1
Added figures
Start-up states
Temperature sense input voltage thresholds
Pulsed maintenance current implementation
1
Updated figures
Figures 1 through 6
1
Added equations
Thermistor divider network configuration equations
1
Raised condition
MOD VOL and VOH parameters from ≤5mA to ≤10µA
1
Corrected Conditions
VSNS rating from VMAX and VMIN to IMAX and IMIN
1
Added table
Capacitance table for CMTO and CPWM
2
6
Changed values in
Figure 5
Was 51K; is now 10K
3
7, 10
Changed values
in Equations 3 and 8
Was: IMAX = 0.275V/RSNS; is now IMAX = 0.250V/RSNS
3
8
Changed values
in Equation 4
Was: (VCC - 0.275); is now (VCC - 0.250V)
3
11
Changed rating value
for VSNS in DC
Thresholds table
Was 0.275; is now 0.250
4
11
TOPR
Deleted industrial temperature range.
Notes:
Change 1 = Dec. 1995 B changes from June 1995 A.
Change 2 = Sept. 1996 C changes from Dec. 1995 B.
Change 3 = April 1997 D changes from Sept. 1996 C.
Change 4 = June 1999 E changes from April 1997 D.
Ordering Information
bq2031
Package Option:
PN
= 16-pin plastic DIP
SN
= 16-pin narrow SOIC
Device:
bq2031 Lead Acid Charge IC
15
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