TDA8035HN Datasheet, PDF (8/32 Pages) NXP Semiconductors – Smart card interface externally by a resistor bridge

NXP Semiconductors
8.2 Voltage supervisor
TDA8035HN
Smart card interface
Vreg
vbg
vreg
VDDP
Deep_shutdown
VDD(INTF)
vbg
Poradj
vbg
001aan747
Fig 3. Block voltage supervisor
The voltage supervisor is used as a power on reset, and also as supply drop detection
during a card session. The threshold of the voltage supervisor is set internally in the IC for
V_DDP and V_REG whereas it can be adjusted externally for V_DD(INTF) using the PORADJ pin.
As long as V_REG is less than Vth(V_REG) + Vhys(V_REG), the IC will remain inactive whatever
the levels on the command lines are. This also lasts for the duration of tw after V_REG has
reached a level higher than Vth(V_REG) + Vhys(V_REG).The outputs of the V_DDP, V_REG and
V_DD(INTF) supervisors are combined and sent to a digital controller in order to reset the
TDA8035. This defined reset pulse of approximately 5.7 ms (tw=2048 × 1/(fosc(int)_Low)
is used internally for maintaining the IC in a inactive mode during the supply voltage
power-on; (see following pictures). When V_REG falls below Vth(V_REG) or when V
DD(INTF)^{falls below Vthextf or when V}DDP ^{falls below Vth(VDDP) , a deactivation sequence}
is performed.
TDA8035HN
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 1.0 — 19 April 2011
© NXP B.V. 2011. All rights reserved.
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