ON MC33340D, MC33342D, MC33340P, MC33342P Schematics

MC33340, MC33342

Battery Fast Charge Controllers

The MC33340 and MC33342 are monolithic control IC’s that are specifically designed as fast charge controllers for Nickel Cadmium (NiCd) and Nickel Metal Hydride (NiMH) batteries. These devices feature negative slope voltage detection as the primary means for fast charge termination. Accurate detection is ensured by an output that momentarily interrupts the charge current for precise voltage sampling. An additional secondary backup termination method can be selected that consists of either a programmable time or temperature limit. Protective features include battery over and undervoltage detection, latched over temperature detection, and power supply input undervoltage lockout with hysteresis. Fast charge holdoff time is the only difference between the MC33340 and the MC33342. The MC33340 has a typical holdoff time of 177 seconds and the MC33342 has a typical holdoff time of 708 seconds.

• Negative Slope Voltage Detection with 4.0 mV Sensitivity

• Accurate Zero Current Battery Voltage Sensing

• High Noise Immunity with Synchronous VFC/Logic

• Programmable 1 to 4 Hour Fast Charge Time Limit

• Programmable Over/Undertemperature Detection

• Battery Over and Undervoltage Fast Charge Protection

• Power Supply Input Undervoltage Lockout with Hysteresis

• Operating Voltage Range of 3.25 V to 18 V

• 177 seconds Fast Change Holdoff Time (MC33340)

• 708 seconds Fast Change Holdoff Time (MC33342)

• Pb−Free Packages are Available

Input

Regulator

Undervoltage

Counter

Timer

Over

Under

Lockout

t/T

Time/ Temp Select

Internal Bias

sen

Gate

Fast/

Trickle

This device contains 2,512 active transistors.

Voltage to

Frequency

Converter

Battery Detect

Ck F/V R

High

Low

−DV Detect

sen

Gate

F/T

GND

Figure 1. Simplified Block Diagram

Over Temp Latch

Temp Detect

Battery

Pack

t1/T

High

ref

t2/T

sen

t3/T

Low

ref

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MARKING

DIAGRAMS

PDIP−8

P SUFFIX

CASE 626

SOIC−8

NB SUFFIX

CASE 751

x = 0 or 2 A = Assembly Location L = Wafer Lot Y = Year W = Work Week G = Pb−Free Package

MC3334xP

AWL

YYWW

3334x

ALYWX

PIN CONNECTIONS

Input

sen

Gate Output

sen

Fast/Trickle Output

Gnd

(Top View)

t1/T

High

ref

t2/T

sen

t3/T

Low

ref

ORDERING INFORMATION

See detailed ordering and shipping information in the package dimensions section on page 13 of this data sheet.

July, 2005 − Rev. 7

1 Publication Order Number:

MC33340/D

MC33340, MC33342

MAXIMUM RATINGS (Note 1)

Rating Symbol Value Unit

Power Supply Voltage (Pin 8) V

Input Voltage Range

Time/Temperature Select (Pins 5, 6, 7) V Battery Sense, (Note 2) (Pin 1) V

Gate Output (Pin 2)

sen

Voltage Current

IR(t/T)

IR(sen)

O(gate)

−1.0 to VCC + 0.6 or −1.0 to 10

Fast/Trickle Output (Pin 3)

Voltage Current

Thermal Resistance, Junction−to−Air

O(F/T)

P Suffix, DIP Plastic Package, Case 626 100

D Suffix, SO−8 Plastic Package, Case 751 178 Operating Junction Temperature T Operating Ambient Temperature (Note 3) T Storage Temperature T

stg

Maximum ratings are those values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit values (not normal operating conditions) and are not valid simultaneously. If these limits are exceeded, device functional operation is not implied, damage may occur and reliability may be affected.

1. This device series contains ESD protection and exceeds the following tests: Human Body Model 2000 V per MIL−STD−883, Method 3015 Machine Model Method 400 V

18 V

−1.0 to V

20 50

°C/W

+150 °C

−25 to +85 °C

−55 to +150 °C

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MC33340, MC33342

ELECTRICAL CHARACTERISTICS (V

= 6.0 V, for typical values TA = 25°C, for min/max values TA is the operating

ambient temperature range that applies (Note 3), unless otherwise noted.)

Characteristic Symbol Min Typ Max Unit

BATTERY SENSE INPUT (Pin 1)

Input Sensitivity for −DV Detection Overvoltage Threshold Undervoltage Threshold Input Bias Current Input Resistance

TIME/TEMPERATURE INPUTS (Pins 5, 6, 7)

Programing Inputs (Vin = 1.5 V)

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Input Current

Input Current Matching Input Offset Voltage, Over and Under Temperature Comparators Under Temperature Comparator Hysteresis (Pin 5) Temperature Select Threshold

INTERNAL TIMING

Internal Clock Oscillator Frequency V

Gate Output (Pin 2)

sen

ББББББББББББББББ

Gate Time

Gate Repetition Rate Fast Charge Holdoff from −DV Detection

ББББББББББББББББ

sen

MC33340

MC33342

GATE OUTPUT (Pin 2) Off−State Leakage Current (VO = 20 V) Low State Saturation Voltage (I

= 10 mA)

sink

FAST/TRICKLE OUTPUT (Pin 3)

Off−State Leakage Current (VO = 20 V) Low State Saturation Voltage (I

= 10 mA)

sink

UNDERVOLTAGE LOCKOUT (Pin 8)

Startup Threshold (VCC Increasing, TA = 25°C) Turn−Off Threshold (VCC Decreasing, TA = 25°C)

TOTAL DEVICE (Pin 8)

Power Supply Current (Pins 5, 6, 7 Open)

ББББББББББББББББ

Startup (V Operating (V

= 2.9 V)

= 6.0 V)

2. Whichever voltage is lower.

3. Tested junction temperature range for the MC33340/342: T

= −25°CT

low

−DV

th(OV)

th(UV)

ÁÁÁ

H(T)

th(t/T)

OSC

gate

ÁÁÁ

hold

ÁÁÁ

off

th(on)

th(off)

ÁÁÁ

high

0.95

2.75

= +85°C

−

1.9

−

−24

−

−4.0

2.0

1.0 10

6.0

−30

ÁÁÁ

1.0

5.0 44

VCC −0.7

760

ÁÁÁ

1.38

ÁÁÁ

177

ÁÁÁ

708

1.2

1.0

3.0

2.85

0.65

ÁÁÁ

0.61

−

2.1

1.05

−

−36

ÁÁ

2.0

−

ÁÁ

−

ÁÁ

−

ÁÁ

−

3.25

−

2.0

ÁÁ

2.0

mV mV

kHz

V V

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MC33340, MC33342

)

sen

2.10 VCC = 6.0 V

2.00

1.90

1.02

1.00

, OVER/UNDERVOLTAGE THRESHOLDS (V

0.98

−50 −25 0 25 50 75 100 125

TA, AMBIENT TEMPERATURE (°C)

Figure 2. Battery Sense Input Thresholds

versus Temperature

−0.2

−0.4

−0.6

−0.8

−1.0

, TEMPERATURE SELECT THRESHOLD VOLTAGE (

Threshold voltage is measured with respect to VCC.

Time mode is selected if any of the three inputs are above the threshold.

Temperature mode is selected when all three inputs are below the threshold.

−50 −25 0 25 50 75 100 125

TA, AMBIENT TEMPERATURE (°C)

VCC = 6.0 V

Figure 4. Temperature Select Threshold Voltage

th(t/T)

versus Temperature

8.0

−8.0

, OSCILLATOR FREQUENCY CHANGE (%Δ

−16

OSC

−50 −25 0 25 50 75 100 125

TA, AMBIENT TEMPERATURE (°C)

VCC = 6.0 V

Figure 3. Oscillator Frequency

versus Temperature

3.2 VCC = 6.0 V

TA = 25°C

2.4

Gate

sen

Pin 2

1.6

Fast/Trickle Pin 3

0.8

, SINK SATURATION VOLTAGE (V)

0 8.0 16 24 32 40

, SINK SATURATION (mA)

sink

Figure 5. Saturation Voltage versus Sink Curren

Gate and Fast/Trickle Outputs

3.1

Startup Threshold

3.0

2.9

, SUPPLY VOLTAGE (V)

2.8

2.7

−50

−25 0 25 50 75 100 125

(VCC Increasing)

Minimum Operating Threshold

(VCC Decreasing)

TA, AMBIENT TEMPERATURE (°C)

Figure 6. Undervoltage Lockout Thresholds

versus Temperature

1.0 TA = 25°C

0.8

0.6

0.4

, SUPPLY CURRENT (mA)

0.2

0 4.0 8.0 12 16

VCC, SUPPLY VOLTAGE (V)

Figure 7. Supply Current

versus Supply Voltage

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MC33340, MC33342

INTRODUCTION

Nickel Cadmium and Nickel Metal Hydride batteries require precise charge termination control to maximize cell capacity and operating time while preventing overcharging. Overcharging can result in a reduction of battery life as well as physical harm to the end user. Since most portable applications require the batteries to be charged rapidly, a primary and u sually a s econdary o r r edundant char ge s ensi ng technique is employed into the charging system. It is also desirable to disable rapid charging if the battery voltage or temperature is either t oo h i gh or too low. In order t o a ddress these issues , an economical a nd flexi ble fa st char ge c ontroller was developed.

The MC33340/342 contains many of the building blocks and protection features that are employed in modern high performance battery charger controllers that are specifically designed for Nickel Cadmium and Nickel Metal Hydride batteries. The device is designed to interface with either primary or secondary side regulators for easy implementation of a complet e charging system. A represent ative block d iagram in a typical charging application is shown in Figure 8.

The battery voltage is monitored by the V

input that

sen

internally connects to a voltage to frequency converter and

Regulator

counter for d etection o f a n egati ve slope in bat tery v ol tage. A timer with three programming inputs is available to provide backup charge termi nation. A lternati vely , these input s ca n be used to monitor the battery pack temperature and to set the over and undertemperature limits also for backup charge termination.

Two active low open collector outputs are provided to interface this controller with the external charging circuit. The first output furnishes a gating pulse that momentarily interrupts the charge c urrent. This a llows a n a ccurate m ethod of sampling the battery voltage by eliminating voltage drops that are associated with high charge currents and wiring resistances. Also, any noise voltages generated by the charging circuitry are eliminated. The second output is designed to switch the charging source between fast and trickle modes based upon the results of voltage, time, or temperature. These outputs normally connect directly to a linear or switching regulator control circuit in non−isolated primary or secondary side applications. Both outputs can be used to drive optoisolators in primary side applications that require galvanic isolation. Figure 9 shows the typical charge characteristics for NiCd and NiMh batteries.

Input

Charge

Status

Reg Control

MC33340 or MC33342

Undervoltage

Under

Over

t/T

Lockout

Time/ Temp Select

sen

Gate

Fast/

Trickle

2.0 V

1.0 V

R2 + R1

Internal Bias

Voltage to

Frequency

Converter

Battery Detect

Batt

–1

sen

Ck F/V R

High

Low

−DV Detect Counter

Timer

sen

Gate

F/T

Gnd

Figure 8. Typical Battery Charging Application

Over Temp Latch

Temp

Detect

0.7 V

2.9 V

30 mA

t1/T

t2/T

t3/T

ref

sen

ref

Battery

High

Low

Pack

SW1

SW3

SW2

NTC

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MC33340, MC33342

1.6

1.5

1.4

1.3

CELL VOLTAGE (V)

1.2

1.1

1.0 0 40 80 120 160

Figure 9. Typical Charge Characteristics for NiCd and NiMh Batteries

Voltage

Temperature

Relative Pressure

CHARGE INPUT PERCENT OF CAPACITY

OPERATING DESCRIPTION

The MC33340/342 starts up in the fast charge mode when power is applied to VCC. A change to the trickle mode can occur as a result of three possible conditions. The first is if the V

input voltage is above 2.0 V or below 1.0 V. Above

sen

2.0 V indicates that the battery pack is open or disconnected, while below 1.0 V indicates the possibility of a shorted or defective cell. The second condition is when the MC33340/342 detects a fully charged battery by measuring a negative slope in battery voltage. The MC33340/342 recognize a negative voltage slope after the preset holdoff time (t

) has elapsed during a fast charge cycle. This

hold

indicates that the battery pack is fully charged. The third condition is either due to the battery pack being out of a programmed temperature range, or that the preset timer period has been exceeded.

There are three conditions that will cause the controller to return from trickle to fast charge mode. The first is if the V

sen

input voltage moved to within the 1.0 to 2.0 V range from initially being either too high or too low . The second is if the battery pack temperature moved to within the programmed temperature range, but only from initially being too cold. Third is by cycling VCC off and then back on causing the internal logic to reset. A concise description of the major circuit blocks is given below.

Negative Slope Voltage Detection

A representative block diagram of the negative slope voltage detector is shown in Figure 10. It includes a Synchronous Voltage to Frequency Converter, a Sample Timer, and a Ratchet Counter. The V

pin is the input for

sen

the Voltage to Frequency Converter (VFC), and it connects to the rechargeable battery pack terminals through a

−DV

CELL TEMPERATURE ( C)°

max

resistive voltage divider. The input has an impedance of approximately 6.0 MW and a maximum voltage range of

−1.0 V to VCC + 0.6 V or 0 V to 10 V, whichever is lower. The 10 V upper limit is set by an internal zener clamp that provides protection in the event of an electrostatic discharge. The VFC is a charge−balanced synchronous type which generates output pulses at a rate of FV = V

(24 kHz).

sen

The Sample Timer circuit provides a 95 kHz system clock signal (SCK) to the VFC. This signal synchronizes the F output to the other Sample Timer outputs used within the detector. At 1.38 second intervals the V

Gate output goes

sen

low for a 33 ms period. This output is used to momentarily interrupt the external charging power source so that a precise voltage measurement can be taken. As the V

Gate goes

sen

low, the internal Preset control line is driven high for 11 ms. During this time, the battery voltage at the V

input is

sen

allowed to stabilize and the previous FV count is preloaded. At the Preset high−to−low transition, the Convert line goes high for 22 ms. This gates the F

pulses into the ratchet

counter for a comparison to the preloaded count. Since the Convert time is derived from the same clock that controls the VFC, the number of FV pulses is independent of the clock frequency. If the new sample has more counts than were preloaded, it becomes the new peak count and the cycle is repeated 1.38 seconds later. If the new sample has two fewer counts, a less than peak voltage event has occurred, and a register is initialized. If two successive less than peak voltage events occur, the −DV ‘AND’ gate output goes high and the Fast/Trickle output is latched in a low state, signifying that the battery pack has reached full charge status.

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