Datasheet

TPS65950
www.ti.com SWCS032E–OCTOBER 2008–REVISED JANUARY 2011
4.3.3 VRRTC LDO Regulator
The VRRTC voltage regulator is a programmable, low dropout, linear voltage regulator supplying (1.5 V)
the embedded real-time clock (32.768-kHz oscillator) and dedicated I/Os of the digital host counterpart.
The VRRTC regulator is also the supply voltage of the power-management digital state-machine. The
VRRTC regulator is supplied from the UPR line, switched on by the main or backup battery, depending on
the system state. The VRRTC output is present as long as a valid energy source is present. The VRRTC
line is supplied by an LDO when VBAT > 2.7, and a clamp circuit when in backup mode. Table 4-21
describes the regulator characteristics.
Table 4-21. VRRTC LDO Regulator Characteristics
Parameter Test Conditions Min Typ Max Unit
Output Load Conditions
Filtering capacitor Connected from VRTC.OUT to analog ground 0.3 1 2.7 μF
Filtering capacitor ESR 20 600 mΩ
Electrical Characteristics
V
IN
Input voltage On mode 2.7 VBAT 4.5 V
V
OUT
Output voltage On mode 1.45 1.5 1.55 V
I
OUT
Rated output current On mode 30 mA
Sleep mode 1
DC load regulation On mode: I
OUT
= I
OUTmax
to 0 100 mV
DC line regulation On mode, V
IN
= V
INmin
to V
INmax
at I
OUT
= I
OUTmax
100 mV
Turn-on time I
OUT
= 0, at V
OUT
= V
OUTfinal
± 3% 100 μs
Wake-up time On mode from low power to On mode, I
OUT
= 0, at 100 μs
V
OUT
= V
OUTfinal
± 3%
From backup to On mode, I
OUT
= 0, at V
OUT
= 100
V
OUTfinal
± 3%
Ripple rejection (VRRTC) f < 10 kHz 50 dB
10 kHz < f < 100 kHz 40
f = 1 MHz 30
V
IN
= V
OUT
+ 1 V, I
O
= I
MAX
Ground current On mode, I
OUT
= 0 70 μA
On mode, I
OUT
= I
OUTmax
100
Sleep mode, I
OUT
= 0 10
Sleep mode, I
OUT
= 1 mA 11
Off mode 1
V
DO
Dropout voltage
(1)
On mode, I
OUT
= I
OUTmax
250 mV
Transient load regulation I
LOAD
: I
MIN
– I
MAX
–40 40 mV
Slew: 40 mA/μs
Transient line regulation V
IN
drops 500 mV 10 mV
Slew: 40 mV/μs
Overshoot Softstart 3%
Pull down resistance Default in off mode 250 320 450 Ω
(1) For nominal output voltage
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