TEA1103 데이터 시트보기 (PDF) - Philips Electronics

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TEA1103

Fast charge ICs for NiCd and NiMH batteries

Philips Electronics 

Philips Semiconductors

Fast charge ICs for NiCd and NiMH

batteries

Preliminary specification

TEA1103; TEA1103T;

TEA1103TS

At an increase of the battery voltage the 14-bit

Analog-to-Digital Converter (ADC) is refreshed with this

new value. Therefore, the digitized value always

represents the maximum battery voltage. A decreased

Vbat voltage is not stored, but is compared to the stored

value.

Full is detected when the voltage decrease of Vbat is 1⁄4%

of the stored peak battery value. To avoid interference due

to the resistance of the battery contacts during battery

voltage sensing, the charge current is regulated to zero

during t = 210 × POD × tosc, via the regulation pins AO and

PWM. At the last period, the Vbat voltage is sensed and

stored in a sample-and-hold circuit. This approach

ensures very accurate detection of the battery full

condition (minus 1⁄4%).

When battery full is determined by ∆T/∆t, the voltage on

the NTC pin is used as the input voltage to the AD/DA

converter. The sampling time at ∆T/∆t sensing is given by

the following equation:

ts

amplin

g





∆--∆---T-t-





=

217 × POD × PSD × tosc

(9)

After this initialized sample time the new temperature

voltage is compared to the preceding AD/DA voltage and

the AD/DA is refreshed with this new value. A certain

increase of the temperature is detected as full battery,

depending on the initialization settings. The decision of full

detection by ∆T/∆t or Vpeak is digitally filtered thus avoiding

false battery full detection.

Output drivers

The charge current regulation signal is available at two

output pins, AO and PWM.

ANALOG OUTPUT

The analog control voltage output at pin 18 (AO) can be

used to drive an opto-coupler in mains separated

applications when an external resistor is connected

between AO and the opto-coupler. The maximum current

through the opto-coupler diode is 2 mA. The voltage gain

of amplifier A2 is typical 11 dB (times 3.5). The DC voltage

transfer is given by the following equation:

VAO = 3.5 × (VLS − 1.35).

The AO output can be used for:

• Linear (DC) applications

• Not mains isolated SMPS with a separate controller

• Mains isolated SMPS, controlled by an opto-coupler.

PULSE WIDTH MODULATOR (PWM)

The LS voltage is compared internally with the oscillator

voltage to deliver a pulse width modulated output at PWM

(pin 15) to drive an output switching device in a SMPS

converter application via a driver stage. The PWM output

is latched to prevent multi-pulsing. The maximum duty

factor is internally fixed to 79% (typ.). The PWM output can

be used for synchronization and duty factor control of a

primary SMPS via a pulse transformer.

1999 Jan 27

11

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