Datasheet

PN532_C1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2017. All rights reserved.
Product data sheet
COMPANY PUBLIC
Rev. 3.6 — 28 November 2017
115436 89 of 222
NXP Semiconductors
PN532/C1
Near Field Communication (NFC) controller
8.4.2 SVDD switch
The SVDD switch is used to control power to the secure IC. The switch is controlled by
register Control_switch_rng (address 6106h). The switch is enabled with bit
sic_switch_en. When disabled, the SVDD pin is tied to ground. A current limiter is
incorporated into the switch. Current consumption exceeding 40 mA triggers the limiter
and the status bit sic_switch_overload is set.
Register Control_switch_rng also controls the random generator within the Contactless
Interface Unit (CIU).
Table 128. Control_switch_rng register (address 6106h) bit allocation
Bit 7 6 5 4 3 2 1 0
Symbol - hide_svdd_
sig
sic_switch_
overload
sic_switch_
en
- cpu_need_
rng
random_
dataready
-
Reset 01 0 000 01
Access R R/W R R/W R R/W R/W R
Table 129. Description of Control_switch_rng bits
Bit Symbol Description
7 - Reserved.
6 hide_svdd_sig Configures internal state of input signals SIGIN and P34 when
idle. This bit can be used to avoid spikes on SIGIN and P34 when the
SVDD switch is enabled or disabled.
When set to logic 0, internal state of SIGIN and P34 are driven by pads
SIGIN and P34 respectively.
When set to logic 1, internal state of SIGIN is set to logic 0 and internal
state of P34 is set to logic 1.
5 sic_switch_overload Indicates state of SVDD switch current limiter. When set to logic 0,
indicates that current consumption through SVDD switch does not
exceed limit (40mA).
When set to logic 1, the SVDD switch current limiter is activated.
4 sic_switch_en Enables or disables power to SVDD switch. When set to logic 0,
SVDD switch is disabled and SVDD output is tied to the ground.
When set to logic 1, the SVDD switch is enabled and the SVDD output
delivers power to secure IC and internal pads (SIGIN, SIGOUT and
P34).
3 - Reserved.
2 cpu_need_rng Forces random number generator into running mode. When set to
logic 0, random number generator is under control of Contactless
Interface Unit.
When set to logic 1, random number generator is forced to run.
1 random_dataready Indicates availability of random number. When set to logic 1, a new
random number is available.
Automatically set to logic 0 when register data_rng (address 6105h) is
read.
0 - Reserved.