NPC SM6780AS Datasheet

−∆

SM6780AS

NIPPON PRECISION CIRCUITS INC.

Ni-Cd/Ni-MH Battery Charger IC

OVERVIEW

The SM6780AS is a quick charge control IC for Nickel-Cadmium (Ni-Cd) and Nickel Metal Hydride (Ni-MH)
rechargeable batteries. It supports quick charge, supplemental and pulse trickle charging modes. The charging
mode is selected automatically in response to the battery voltage, temperature and charging time.

The quick charge uses either negative delta voltage detection ( −∆ V), temperature detection ( ∆ T/ ∆ t), or charg­ing time cutoff to control the charging process. In addition, the quick charge mode can be placed on hold, if the
battery voltage or battery temperature are abnormal, until normal conditions are restored.

The SM6780AS requires few external components to realize a high-stability quick charge battery charger.

FEATURES

■

Ni-Cd/Ni-MH battery quick charge control

■

V, ∆ T/ ∆ t, and maximum charge time cutoffs

■

3 charge modes (quick charge, supplemental,
pulse trickle charge)

■

3 selectable charge times (80, 120, and 240 min­utes)

■

Charge condition LED indicator output (on,
pulsed, off)

■

Low power dissipation mode

■

4.0 to 5.5V operating supply voltage

■

300sec (typ) −∆ V detection invalid time

■

8mV (typ) −∆ V detection accuracy

■

25mV/min (typ) ∆ T/ ∆ t detection accuracy

■

8-pin SOP package

PINOUT

(Top view)

TIME CHGN

LEDN

BATT

VSS

6780AS

INH
VDD
TEMP

ORDERING INFORMATION

Device Package

SM6780AS 8-pin SOP

PACKAGE DIMENSIONS

(Unit: mm)

4.4 0.2

6.2 0.3

0.695typ

1.5 0.1

1.27

5.2 0.3

0.05 0.05

0.10

0.4 0.1

M

0.12

NIPPON PRECISION CIRCUITS—1

0.15

− 0.05

0.4 0.2

+

0.1

0 to 10

BLOCK DIAGRAM

DC

Input

SM6780AS

VDD

TIMEVDD

Current

Source

Battery

Pack

NTC

BATT

TEMP

Reference

Regulators

Maximum

Cell-voltage Check

Input Select

Temp Check

A/D

OSC

−∆V

Function

Block

∆V/∆t

Function

Block

VSS

PIN DESCRIPTION

Number Name Description

1 TIME

2 LEDN

3BATT

4 VSS Ground
5 TEMP Battery temperature thermistor sensor voltage input
6 VDD Supply

7 INH

8 CHGN

Charge time select 3-level input.
HIGH: 240 minutes, MID (V

/2): 120 minutes, LOW: 80 minutes

DD

Charge indicator LED driver output.
Open-drain output. LOW-level output in quick charge mode. 1Hz pulse output when abnormal battery voltage or
temperature is detected during quick charge mode. High impedance output in supplemental and trickle charge
modes.

Battery voltage detector input.
Connect a high-impedance resistor voltage divider between the poles of the battery for v oltage detection.

Charge inhibit input.
Charging is stopped when HIGH. Charging resumes with the same charge parameters in force prior to the stop
when INH goes LOW again.

Charger control output.
Open-drain output. Battery charging current flows when CHGN is high impedance. Charge current stops when
LOW. High-impedance output in quick charge mode, and pulse output in supplemental and trickle charge
modes.

Timer Mode

Selector

Timing Control

Logic

Charge Control

Logic

CHGN

CHG Driver

VDD

LEDN

LED Driver

VDD

INH

NIPPON PRECISION CIRCUITS—2

≤

≤

≤

−

−

SPECIFICATIONS

Absolute Maximum Ratings

V

= 0V

SS

Parameter Symbol Condition Rating Unit

Supply voltage range V
Input voltage range V
Storage temperature range T
Operating temperature range T
Power dissipation P

DC Characteristics 1

DD

IN

stg

opr

D

−

−

−

−

SM6780AS

0.3 to 7.0 V

0.3 to 7.0 V
55 to 125

0 to 85

150 mW

° C
° C

V

= 4.0 to 5.5V, V

DD

= 0V, Ta = 25 ° C

SS

Parameter Symbol Condition Rating Variation Unit

Maximum temperature voltage V
High-temperature sense

voltage
Low-temperature sense voltage V

Maximum battery voltage V

V

MXT

HTS

LTS

MXV

DC Characteristics 2

V

= 4.0 to 5.5V, V

DD

Parameter Symbol Condition

VDD supply voltage V
BATT input voltage V
TEMP input voltage V
INH HIGH-level input voltage V
INH LOW-level input voltage V
TIME HIGH-level input voltage V
TIME MID-level input voltage V
TIME LOW-level input voltage V

V detection voltage range V

BATT −∆
LEDN output pulse frequency f
BATT standby voltage V
VDD current consumption I
VDD standby current I
LEDN, CHGN sink current I
INH, TIME input leakage current I
LEDN, CHGN output leakage

current

= 0V, Ta = 0 to 85 ° C unless otherwise noted

SS

DD

BATT

TEMP

IH1

IL1

IH2

IM

IL2

DET

LED

STB

DD

STB

OL

L

I

OZ

V

V

TEMP

V

V

HTS

V

> V

TEMP

V

> V

BATT

prohibition

charge cutoff 0.225V

MXT

V

TEMP

LTS

MXV

charge start 0.25V

LTS

charge prohibition 0.4V
charge cutoff or

DD

DD

DD

2.0 ±5% V

±5% V

±5% V

±5% V

Rating

min typ ma x

4.0 5.0 5.5 V
0–V

Disabled when V

< 0.5V 0.5 – V

TEMP

0.7 – – V
– – 0.1 V

V

− 0.5 – – V

DD

(V

/2) − 0.5 – (V

DD

– – 0.5 V
1–2V
–1–Hz

V

1.5 – V

DD

V

= 5V, no load – – 0.5 mA

DD

V
V
V

DD

OL

INH

= 5V, V

= V

= V

= V

BATT

+ 0.8V 10 – – mA

SS

TIME

, no load – – 1 µA

DD

= V

to V

SS

DD

––±1µA

5– –µA

DD

DD

/2) + 0.5 V

DD

0.5 V

DD

Unit

V
V

NIPPON PRECISION CIRCUITS—3

FUNCTIONAL DESCRIPTION

Charger Operation

SM6780AS

The SM6780AS battery charger operation starts
when the power is applied or when standby mode is
released. The charging operation is determined by
the BATT and TEMP pin states, and the timer mode
selected.

After charging starts, the battery voltage and temper­ature are monitored to check that they are within
quick charging rated ranges. If within rated range,
quick charge mode is selected. If outside rated range,
pulse trickle charge mode is selected.

Charging Rate

The charging rate is determined by the external
charger current source. If the quick charge mode
charging rate is considered as unity, then the supple­mental charging rate is 1/16, and the pulse trickle
charging rate is 1/256. The charging rate for supple-

286µs

Hi-Z

Low

4576µs

Quick charge uses either negative delta voltage
detection ( −∆ V), temperature detection ( ∆ T/ ∆ t), or
charging time cutoff to terminate the charging pro­cess. The charging mode changes to supplemental
charge mode when quick charge mode is completed.

Supplemental mode terminates when the charging
time finishes or battery is full, and the charging mode
changes to pulse trickle mode.

mental and pulse trickle modes are shown in figure 1.
The CHGN output is high impedance when the
charging current is flowing, and LOW when the cur­rent stops.

286µs

73.1ms

Quick charge

mode

Start
(power ON or battery insertion)

Supplemental

charge mode Pulse trickle mode

Figure 1. CHGN output (external charger control)

Charging Status Indicator LED Control (LEDN)

The SM6780AS LEDN output can be used to drive a
charging status indicator LED.

The LED timing when power is applied or standby
mode is released is shown in figure 2.

Hi-Z

LED OFF

Low

Approximately

1.5 s

Power ON or Standby mode cancel

LED ON

Approximately

3.5 s

In quick charge mode, the LEDN output is LOW and
the LED turns ON. If the battery temperature or bat­tery voltage exceeds the charging rated ranges, the
LEDN output pulses at a frequency of 1Hz to indi­cate battery out-of-range condition. In supplemental
and pulse trickle modes, the LEDN output is high
impedance and the LED turns OFF.

Depends on charge mode

Figure 2. LEDN output timing

NIPPON PRECISION CIRCUITS—4