SA305 Datasheet, PDF (8/8 Pages) Cirrus Logic – PULSE WIDTH MODULATION AMPLIFIER

SA305
OPERATING
CONSIDERATIONS
The warning temperature setting is fixed at T_J = 135°C.
When the junction temperature gets to the programmed point,
the temperature warning bit will be set. It will be reset when
the temperature falls below 85°C.
The Fault temperature setting is fixed at T_J = 160°C. Once
the Fault temperature has been reached the Fault Output goes
high and the outputs of the device are latched off. This output
can be used as a microcontroller interrupt. The latch will not
be reset until the temperature is below 110°C.
If more than one output is required to be conducting large
currents at the same time, the maximum current will need to
be de-rated.
CURRENT SENSE LINEARITY CALCULATION
The current sense linearity is calculated using the method
described below:
a) Define straight line (y = mx + c) joining the two end data
points where, m is the slope and c is the offset or zero
crossover. Calculate the slope m and offset c using the
extreme data points. Assume Isense in the y axis and Iload
in the x axis.
b) Calculate linear Isense (or ideal Isense value, IS_IDEAL) using
the straight line equation derived in step (a) for the Iload
data points.
c) Determine deviation from linear Isense (step (b)) and actual
measured Isense value (IS_ACTUAL) as shown below:

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*4_*%&"-
m
*4_"$56"-
*4_*%&"-
r

T_Ah_Pis_Ed_Xata_Ms_Ih_Ce_Ret_Oh_Ta_Es_Cb_Hee_Nn_Oc_Lar_Oef_Gu_Ylly _Cch_Oe_Rck_Pe_Od _Ran_Ad_Ti_Is_Ob_Nelie_•ve₅d₉to₈b₀e r_Nel_Oia_Rb_Tle_H, ho_Sw_He_Ave_Nr,_Nn_Oo _Nresp_Ro_On_Asib_Dilit_•y i_Ts_Uas_Cs_Su_Ome_Nd_,fo_Ar_Rp_Io_Zss_Oib_Nle_Aina₈c₅cu₇r₄ac₁ies_•or_Uo_Sm_Aissi_•on_As._PA_Pll_Ls_Ip_Cec_Ai_Tfic_Ia_Ot_Nion_Ss _Har_Oe _Tsu_Lb_Ij_Nec_Et_:to₁ch₍a₈ng₀e₀w₎ith₅o₄u₆t n_-2ot₇ic₃e.₉

SA305U REV D AUGUST 2007 © 2007 Apex Microtechnology Corp.