Philips 74LV4799SN, 74LV4799SD, 74LV4799PW, 74LV4799N, 74LV4799D Datasheet

INTEGRATED CIRCUITS

74LV4799

Timer for NiCd and NiMH chargers

Product specification

1998 Apr 20

Supersedes data of 1998 Apr 07

IC24 Data Handbook

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Philips Semiconductors	Product specification
Timer for NiCd and NiMH chargers	74LV4799

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

•ICC 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

			LED			1			16			VCC
				EN		2			15			SCI
						3			14			SCAN
				EN
				Vin		4			13			IOSC
	PWRS					5			12			RS
						6			11			RD
	MOLLI/SCO
			SEL			7			10			RC
		GND				8			9			DIS
										SV01643

QUICK REFERENCE DATA

GND = 0V; Tamb = 25°C

SYMBOL	PARAMETER	CONDITIONS	TYPICAL	TYPICAL	TYPICAL	UNIT
VCC	DC supply voltage		0.9		6.0	V
		VCC = 3.3V; self-discharge mode;				μA
ICC	Operating supply current	Rs = 100 k ;		36
		C1 = 220nF
f	Oscillator frequency tolerance	VCC = 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

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853-2058 19258

Philips Semiconductors	Product specification
Timer for NiCd and NiMH chargers	74LV4799

FUNCTIONAL DIAGRAM

						4
					POWER±ON	Vin
	VCC
					RESET
							EN	2
							EN
	SEL							3
7
	DIS
9
	PWRS
5
	SCAN				CONTROL LOGIC
14						GND	GND
	SCI
15
	GND					MOLLI/SCO		6
	GND					10±STAGE
			3±STAGE		5±14 STAGE
	GND
		CP				UP/DOWN
			DIVIDER		DIVIDER
						COUNTER
							GND
13	IOSC		OSCILLATOR		CP
							LED
								1
							GND
			RC	RD	RS
			10	11	12		SV01644

IEC LOGIC SYMBOL

				F
			BATT. TIMER
	13	G						4
		IOSC			U+[1]
12								2
		RS			EN
11
								3
		RD
10
		RC
9		1
		DIS
15
		SCI			SCO			6
14
		SCAN/Z1			MOLLI
		I=0						16
5				CT=0	U+[2]
		PWRS						8
					0V
7								1
		SEL			LED
								SV01645

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Philips Semiconductors	Product specification
Timer for NiCd and NiMH chargers	74LV4799

PIN DESCRIPTION

PIN NO.						SYMBOL	NAME AND FUNCTION
1							LED driver output pin (active LOW)
		LED
2		EN					Enable output (active HIGH)
3							Enable output (active LOW)
		EN
4		Vin					External power input
5		PWRS					Power sense input
6							More-or-less-low-indication output (active LOW)/scan test output
		MOLLI/SCO
7		SEL					LED mode select input
8		GND					Ground (0 V)
9							Discharge input (active LOW)
		DIS
10		RC					External resistor pin 3-State oscillator output (charge)
11		RD					External resistor pin 3-State output (discharge)
12		RS					External resistor pin 3-State output (self-discharge)
13		IOSC					Oscillator input
14		SCAN					Scan test mode select input (active HIGH)
15		SCI					Scan test input
16		VCC					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 RC 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 VIN input. The voltage on the VIN 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 RC 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 RC -C1 time-constant, and 3 periods of the RS -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 RD 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 RD 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.

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Philips Semiconductors	Product specification
Timer for NiCd and NiMH chargers	74LV4799

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 RS 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 IOSC pin (pin 13). In the scan mode, the on±chip 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 IOSC 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 ªApplication informationº.

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

MODES

PWRS

VIN

DIS

EN

EN

RC

RD

RS

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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Philips Semiconductors	Product specification
Timer for NiCd and NiMH chargers	74LV4799

FUNCTION TABLE 2

STATUS

INPUTS

OUTPUTS

COUNTER

INDICATION

PWRS

SEL(1)

MODE

VALUE

DIS

LED

MOLLI

Charge

H or

H

L

L

Z

Count up

< max

H or

H

H or open

Z

Count up

< max

Charge/discharge

H or

L

L

L

Z

Count down

≥

min

Trickle charge

H or

H

L

Z

Stop

max

H or

H

H or open

L

Z

Stop

max

Discharge

L or open

L

X

Z

Z

Count down

> min

Self-discharge

L or open

H

X

Z

Z

Count down

> min

Low

L or open

↑

X

Z

Stop

min

Low

↑

↑

X

Z

Z(2)

Count up

≥

min

Alarm

H or

L

H or open

Z

Count down

≥

min

NOTES:

1.Don't change SEL during operation.

2.The MOLLI function will be interrupted as soon as PWRS is activated.

H			=			HIGH voltage level
L			=			LOW voltage level
Z			=			high impedance OFF-state
X			=			don't care
					=	pulsed (H/L)
					=	pulsed (Z/L)

= 4 periods of about one second (Z/L)

↑= LOW-to-HIGH level transition

Z±state	Z±state
R C
Z±state	Z±state
R S
I OSC

EN

Z±state

EN

Operation in the trickle charge mode. The duration of the RC cycle determines the duty cycle of the enable outputs (EN and EN), allowing a dedicated control. The average trickle charge current will compensate for the self-discharge, independent of the charge current.

SV01646

Figure 1. Trickle charge mode characteristics.

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