Philips
Semiconductors
74LV4799
Timer for NiCd and NiMH chargers
Product specification
Supersedes data of 1998 Apr 07
IC24 Data Handbook
1998 Apr 20
INTEGRATED CIRCUITS
Philips Semiconductors
Product specification
74LV4799
Timer for NiCd and NiMH chargers
2
1998 Apr 20
853-2058 19258
FEATURES
Wide supply voltage range of 0.9 V to 6 V allows 1 to 4-cell
applications
10 V allowed on special inputs
Supports virtually all battery chargers, including switched-mode
power supplies
On-chip timer calculates the actual capacity of the battery by
measuring the charger time, discharge time and self-discharge time
Automatic switch-over to trickle charge after completion of the
charge time
Can be adjusted for use with different types of batteries:
Charge time: 4 to 16 hours
Discharge time: 15 minutes to 4.7 hours
Self-discharge time: 50 to 100 days
Battery status indication included:
LED output for charging/full indication
MOLLI output for battery-low indication
LED mode select allows two different methods of indication
Automatic power-ON reset
Low-power consumption
Requires only a few peripheral components
Very accurate on-chip oscillator
Scan test facilities included
I
CC
category: non-standard.
APPLICATIONS
Time-controlled NiCd and NiMH low-current chargers
Domestic appliances such as rechargeable battery shavers,
electric toothbrushes etc.
Portable equipment such as notebook PCs, laptop PCs, camera
flash units etc.
Personal communications like cordless telephones, personal
mobile radios, pagers, etc.
DESCRIPTION
The 74LV4799 is a low-voltage Si-gate CMOS control IC for battery
management. It consists of:
17-stage divider
10-stage up/down counter
Control logic
Integrated precision oscillator (using external timing components)
Automatic power-ON reset
Scan test facilities
Battery charging/full indication output (LED)
Battery-low indication output (MOLLI)
Open-drain-N outputs for driving the load transistor
Battery management with the 74LV4799 is based on the principle of
time measurement. It measures the charge time, discharge time and
self-discharge time by means of a very accurate on-chip oscillator, a
divider and an up/down counter.
PIN CONFIGURATION
SV01643
1
2
3
4
5
6
LED
EN
EN
V
in
PWRS
MOLLI/SCO
V
CC
SCI
SCAN
16
15
14
13
12
11
7
8
GND
R
C
DIS
10
9
SEL
I
OSC
R
S
R
D
QUICK REFERENCE DATA
GND = 0V; T
amb
= 25
C
SYMBOL
PARAMETER
CONDITIONS
TYPICAL
TYPICAL
TYPICAL
UNIT
V
CC
DC supply voltage
0.9
6.0
V
I
CC
Operating supply current
V
CC
= 3.3V; self-discharge mode;
R
s
= 100 k
W
;
C
1
= 220nF
36
A
D
f
Oscillator frequency tolerance
V
CC
= 1 to 6 V
7
%
ORDERING INFORMATION
PACKAGES
TEMPERATURE RANGE
OUTSIDE NORTH AMERICA
NORTH AMERICA
CODE
16-Pin Plastic DIL
0
C to +70
C
74LV4799 N
74LV4799 N
SOT38-4
16-Pin Plastic SO
0
C to +70
C
74LV4799 D
74LV4799 D
SOT109-1
16-Pin Plastic SSOP Type II
0
C to +70
C
74LV4799 DB
74LV4799 DB
SOT338-1
16-Pin Plastic TSSOP Type I
0
C to +70
C
74LV4799 PW
74LV4799PW DH
SOT403-1
Philips Semiconductors
Product specification
74LV4799
Timer for NiCd and NiMH chargers
1998 Apr 20
3
FUNCTIONAL DIAGRAM
SV01644
OSCILLATOR
CP
GND
GND
MOLLI/SCO
LED
EN
EN
GND
IOSC
RC
RD
RS
13
15
14
5
9
7
SCI
SCAN
PWRS
DIS
SEL
CP
3STAGE
DIVIDER
514 STAGE
DIVIDER
POWERON
RESET
CONTROL LOGIC
10STAGE
UP/DOWN
COUNTER
VCC
4
10
11
1
6
3
Vin
2
12
GND
GND
GND
GND
IEC LOGIC SYMBOL
SV01645
IOSC
RS
RD
DIS
RC
SCI
SCO
MOLLI
EN
4
2
3
6
16
8
1
LED
0V
U+[2]
U+[1]
1
SCAN/Z1
PWRS
SEL
CT=0
G
I=0
F
BATT. TIMER
13
12
11
10
9
15
14
5
7
Philips Semiconductors
Product specification
74LV4799
Timer for NiCd and NiMH chargers
1998 Apr 20
4
PIN DESCRIPTION
PIN NO.
SYMBOL
NAME AND FUNCTION
1
LED
LED driver output pin (active LOW)
2
EN
Enable output (active HIGH)
3
EN
Enable output (active LOW)
4
V
in
External power input
5
PWRS
Power sense input
6
MOLLI/SCO
More-or-less-low-indication output (active LOW)/scan test output
7
SEL
LED mode select input
8
GND
Ground (0 V)
9
DIS
Discharge input (active LOW)
10
R
C
External resistor pin 3-State oscillator output (charge)
11
R
D
External resistor pin 3-State output (discharge)
12
R
S
External resistor pin 3-State output (self-discharge)
13
I
OSC
Oscillator input
14
SCAN
Scan test mode select input (active HIGH)
15
SCI
Scan test input
16
V
CC
Positive supply voltage
Power On Reset.
An automatic Power On Reset initiates the IC when the battery is
discharged and power is connected to the circuit. The initial
condition is the charge mode in which the counter is reset and
counts from zero up to maximum. At start up, the battery therefore
always receives a full charge cycle. When a partially charged battery
is inserted, it may be over-charged during the first cycle. To guard
against this, simply replace the resistor at the R
C
pin with an NTC
type which is in good thermal contact with the battery. If the
temperature of the battery increases, the frequency of the oscillator
also increases to quickly reach a counter full indication and
switch-over to trickle charge. With a battery that is almost
completely discharged, the POR input can also be activated during
discharge or self-discharge. The counter will then be reset to zero.
This is a correct action while returning to the initial condition.
Power-on sensing.
Because this IC supports virtually all battery chargers, the PWRS input
has a broad input frequency spectrum (active HIGH to 100 kHz). A
pull-down circuit at the PWRS input allows detection of the open state
which corresponds to an inactive charger. A HIGH level on the PWRS
input, or an AC signal up to 100 kHz, enables the charge mode.
Start-up with low battery voltage.
Good start-up, even with an un-charged battery, is assured by using
the V
IN
input. The voltage on the V
IN
input biases the external
bipolar transistors at the EN or EN output, even if the IC is not yet
functioning. After the battery has received sufficient charge, the
internal control logic takes over control of the EN and EN outputs.
Charge mode.
This mode is selected when PWRS is active (HIGH or pulsed) and
the discharge input DIS is HIGH. The EN output is HIGH, and the
EN output is LOW initiating continuous charge of the battery. The
counter then counts from the zero state up to the maximum value.
The clock frequency is determined by the external capacitor and
resistor connected to the R
C
output. The counter stops when it
reaches its maximum value and the EN and EN outputs switch over
from the continuous charge to the trickle charge mode.
Trickle charge mode.
At the maximum counter value, it is assumed that the battery is fully
charged. The counter stops and remains on this maximum value.
The EN and EN outputs switch over from the continues charge to
the trickle charge mode. In the trickle charge mode, the average
charge current is reduced to only compensate the self-discharge of
the battery by using the dedicated duty cycle control. The control is
dedicated because it adjusts the duty cycle in inverse proportion to
the load current, resulting in a fixed charger current irrespective of
the kind of charger (e.g. 4-hour or 16-hour charger). In the trickle
charge mode, the oscillator circuitry alternately generates 4 periods
of R
C
-C1 time-constant, and 3 periods of the R
S
-C1 time-constant
(See Figure 1).
Discharge mode.
The discharge input (DIS) is used to detect the discharge of the
battery. If DIS is LOW, the counter counts down. The clock
frequency is determined by the external capacitor and resistor at the
R
D
output. If PWRS is inactive (LOW or open), the EN output is
LOW, and the EN output is in the high impedance OFF-state (no
charge of the battery). This is called the discharge mode. If PWRS is
active, the circuit is in the charge/discharge mode.
Charge/Discharge mode.
If DIS is LOW and PWRS is active (HIGH or pulsed), the circuit is in
the charge/discharge mode. The counter counts down. The clock
frequency is determined by the external capacitor and resistor tied
at the R
D
output. The EN output is HIGH, and the EN output is LOW
initiating continuous charge of the battery. The battery is therefore
charged and discharged at the same instant, thereby maintaining a
better load condition of the battery.
Philips Semiconductors
Product specification
74LV4799
Timer for NiCd and NiMH chargers
1998 Apr 20
5
Self-discharge mode.
If DIS is HIGH and PWRS is inactive (LOW or open), the battery is
being neither charged nor discharged. The circuit is in the
self-discharge mode. This mode represents the battery leakage
(self-discharge). The counter counts down. The clock frequency is
determined by the external capacitor and resistor at the R
S
output.
When the counter reaches the zero state, it stops.
LED mode select.
The LED output drives a battery status LED which indicates the
charge/full status of the battery. For optimum flexibility, two modes of
operation are built-in.
Mode 1: If SEL is LOW, the LED output is active LOW in the
charge mode, and the LED blinks with a frequency of
about 1 Hz during trickle charge.
Mode 2: If SEL is HIGH or open, the LED output blinks with a
frequency of about 0.25 Hz in the charge mode, and is
active LOW during trickle charge. In the discharge or
self-discharge mode, the LED output is open except
when PWRS is active (HIGH or pulsed). Then, the
battery is charging and discharging simultaneously.
Although the discharge mode is dominant, the LED
output is active when PWRS is also active.
NOTE: The blink frequency depends on the oscillator frequency.
(See application information)
Low indication.
As part of the user interface, the MOLLI output shows when the
battery needs to be charged. MOLLI stands for More Or Less Low
Indication (active LOW). The function is as follows: In the discharge
mode, (DIS is active LOW), the counter counts down and, when it
reaches the zero state, it stops. If DIS is switched HIGH, the MOLLI
output gives an output signal of four periods of about one second,
with a 50% duty cycle. This can be used to activate a buzzer. The
MOLLI output signal of four periods will be interrupted as soon as
PWRS is activated.
Alarm indication.
If an almost completely discharged battery is connected to the
charger, it may not be noticed by the user if the load switch is still
on. To prevent damaging the battery, an alarm signal on the LED
output will alert the user to switch off the load. The alarm signal is
easily recognized, because the LED output will blink at a higher
frequency than normal (about 5 Hz instead of 1 Hz). This alarm
indication is only active if the SEL input is HIGH or open. If the SEL
input is LOW, no alarm indication is present, because in many
applications simultaneous charging and discharging is quite
acceptable. (See charge/discharge mode)
Scan test mode.
If the SCAN input (pin 14) is made active HIGH, the circuit is in the
test mode. The tester clock is connected to the I
OSC
pin (pin 13). In
the scan mode, the onchip oscillator is bypassed to allow rapid
testing of the divider/counter. The scan test patterns are available on
request. The scan test data is entered serially through the SCI input
(pin 15). The scan out data is present on the MOLLI/SCO output
(pin 6), which then acts as a scan output.
Remaining energy indication.
The scan test facility can be used as a remaining energy indication
because the value of the counter can be read out at the scan output
(MOLLI/SCO). This is done by briefly interrupting the normal mode
of operation, putting the circuit in the scan mode, and reading out
the counter value. The circuit then reverts to the normal mode. This
only works correctly with the MOLLI/SCO output and SCI input
linked (round coupled loop) and with exactly 49 clock pulses applied
to the I
OSC
input.
The serial scan-out data is available on the MOLLI/SCO output. The
value of the counter can be decoded by reading the correct bits.
Details are given later in the section "Application information".
Output drivers EN and EN.
In one-cell battery (low-voltage) applications, the drive from the
ENABLE output (EN) is insufficient to provide the base current directly
for the external bipolar PNP regulator transistor. The inverse signal has
therefore been made available at the ENABLE output (EN) to drive an
extra bipolar NPN transistor that can provide the base current for the
bipolar PNP regulator transistor as shown in Figure 2.
FUNCTION TABLE 1
OPERATING
INPUTS
OUTPUTS
DIVIDER/COUNTER
OPERATING
MODES
PWRS
V
IN
DIS
EN
EN
R
C
R
D
R
S
MODE
VALUE
Charge
H or
H
H
H
L
Z
Z
Count up 22 sections
<
max
Trickle charge
H or
H
H
Z
Stop
max
Charge/discharge
H or
H
L
H
L
Z
Z
Count down 18 sections
min
Discharge
L or open
X
L
L
Z
Z
Z
Count down 18 sections
min
Self-discharge
L or open
X
H
L
Z
Z
Z
Count down 27 sections
min
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