AIC1803 データシートの表示（PDF） - Analog Intergrations

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AIC1803

Three-Cell Lithium-Ion Battery Protection IC

Analog Intergrations 

CTC ‚CTD(F)

TOC ‚TOD(S)

CTC ‚CTD(F)

TOC ‚TOD(S)

1n 5n 10n 22n 33n

21m 52m 132m 253m 347m

47n 68n 82n 100n

617m 748m 1004m 1630m

The delay time can also be approximately

calculated by the following equations (if CTC , CTD

≤ 82nF) :

TOC(mS) = 11.8 x CTC(nF)

TOD(mS) = 11.8 x CTD(nF)

Setting the Overcurrent Delay Time 1

The overcurrent delay time 1 (TOI1) at 0.15V <

- VCC VCS < 0.3V is set by the external capacitor CTI,

while the overcurrent delay time 2 and 3 (TOI2 and

TOI3) is fixed by IC internal circuit.The relationship

between capacitance of the external capacitor and

delay time is tabulated as below.

CTI(F) 1n 2.2n 3.3n 5n

TOI(mS) 4.8 15.0 18.8 23.6

6.8n

31.0

10n

61.8

Selection of External Control

MOSFETs

Because the overcurrent protection voltage is

preset, the threshold current for overcurrent

detection is determined by the turn-on resistance

of the discharge control MOSFET M1. The turn-on

resistance of the external control MOSFETs can

be determined by the equation: RON=VOIP/IT (IT is

the overcurrent threshold current). For example, if

the overcurrent threshold current IT is designed to

be 5A, the turn-on resistance of the external

control MOSFETs must be 30mΩ. Users should

AIC1803

be aware that turn-on resistance of the MOSFET

changes with temperature variation due to heat

dissipation. It changes with the voltage between

gate and source as well. (Turn-on resistance of a

MOSFET increases as the voltage between gate

and source decreases). Once the turn-on

resistance of the external MOSFET changes, the

overcurrent threshold current will change

accordingly.

Suppressing the Ripple and

Disturbance from Charger

To suppress the ripple and disturbance from

charger, connecting R1 to R4 and C1 to C4 is

recommended.

Controlling the Charge Control

MOSFET

R5, R6, R7 and NPN transistor Q1 are used to

switch the charge control MOSFET M2. If

overcharge does not occur, no current flows into

OC pin and Q1 is turned off, then M2 is turned on.

When overcharge occurs, current flows into OC

pin and Q1 is turned on, which turns off M2 in turn.

Protection at CS Pin

R8 is used for protection of IC when charger is

connected in reverse. The charge detection

function after overdischarge is possibly disabled

by larger value of R8. Resistance of 1KΩ is

recommended.

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