MMPF0100 datasheet(98/136 Pages) NXP

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NXP Semiconductors

PF0100

FUNCTIONAL BLOCK REQUIREMENTS AND BEHAVIORS

6.4.7.1

Coin cell battery backup

The LICELL pin provides for a connection of a coin cell backup battery or a “super” capacitor. If the voltage at VIN goes below the VIN

threshold (VTL1 and VTL0), contact-bounced, or removed, the coin cell maintained logic is powered by the voltage applied to LICELL. The

supply for internal logic and the VSNVS rail switches over to the LICELL pin when VIN goes below VTL1 or VTL0, even in the absence of

a voltage at the LICELL pin, resulting in clearing of memory and turning off of VSNVS. When system operation below VTL1 is required,

for systems not utilizing a coin cell, connect the LICELL pin to any system voltage between 1.8 V and 3.0 V. A small capacitor should be

placed from LICELL to ground under all circumstances.

6.4.7.1.1

Coin cell charger control

The coin cell charger circuit functions as a current-limited voltage source, resulting in the CC/CV taper characteristic typically used for

rechargeable Lithium-Ion batteries. The coin cell charger is enabled via the COINCHEN bit while the coin cell voltage is programmable

through the VCOIN[2:0] bits on register COINCTL on Table 113. The coin cell charger voltage is programmable. In the on state, the

charger current is fixed at ICOINHI. In Sleep and Standby modes, the charger current is reduced to a typical 10

μA. In the off state, coin

cell charging is not available as the main battery could be depleted unnecessarily. The coin cell charging stops when VIN is below UVDET.

VSNVS AC and transient (continued)

VSNVSLOTR

Transient load response

• VSNVSVOLT[2:0] = 110

• 3.1 V (UVDETL)< VIN ≤ 4.5 V

• ISNVS = 75 to 750 μA

• VSNVSVOLT[2:0] = 000 to 101

• 2.45 V < VIN ≤ 4.5 V

• VTL0 > VIN, 1.8 V

≤ VCOIN ≤ 3.3 V

• ISNVS = 40 to 400 μA

• Refer to Figure 31

2.8

–

1.0

–

2.0

VSNVS DC, switch

VINSNVS

Operating input voltage

• Valid coin cell range

1.8

–

3.3

ISNVS

Operating load current

5.0

–

400

μA

RDSONSNVS

Internal switch RDS(on)

• VCOIN = 2.6 V

–

100

VTL1

VIN threshold (VIN powered to coin cell powered)

• VSNVSVOLT[2:0] = 110

2.725

2.90

3.00

(80)

VTH1

VIN threshold (coin cell powered to VIN powered)

• VSNVSVOLT[2:0] = 110

2.775

2.95

3.1

Notes

77.

For 1.8 V ISNVS limited to 100 μA for VCOIN < 2.1 V

78.

The start-up of VSNVS is not monotonic. It first rises to 1.0 V and then settles to its programmed value within the specified tr1 time.

79.

From coin cell insertion to VSNVS =1.0 V, the delay time is typically 400 ms.

80.

During crossover from VIN to LICELL, the VSNVS output voltage may drop to 2.7 V before going to the LICELL voltage. Though this is outside

the specified DC voltage level for the VDD_SNVS_IN pin of the i.MX 6, this momentary drop does not cause any malfunction. The i.MX 6’s RTC

continues to operate through the transition, and as a worst case it may switch to the internal RC oscillator for a few clock cycles before switching

back to the external crystal oscillator.

Table 111. VSNVS electrical characteristics (continued)

All parameters are specified at TMIN to TMAX (See Table 3), VIN = 3.6 V, VSNVS = 3.0 V, ISNVS = 5.0 μA, typical external component values,

unless otherwise noted. Typical values are characterized at VIN = 3.6 V, VSNVS = 3.0 V, ISNVS = 5.0 μA, and 25 °C, unless otherwise

noted.

Symbol

Parameter

Min

Typ

Max

Unit

Notes

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