SMB218 查看數據表（PDF） - Summit Microelectronics

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SMB218

Six-Channel Programmable DC-DC Power Managers with Battery Charger

Summit Microelectronics 

PLEASE NOTE: The SMB118 has entered End-of-Life.

SMB118/218

APPLICATIONS INFORMATION (CONTINUED)

BATTERY MONITORING

The battery voltage is monitored for two user-

programmable UV settings via the VBATT pin. In

addition, the battery charging input, DOCK_DC, is

provided to monitor for the presence of a battery

charging docking station, or AC wall adaptor.

Monitoring is accomplished by a comparator-based

approach, in which a programmable voltage reference

is compared against the monitored signal. Each

channel possesses a dedicated reference voltage

generated by a programmable level shifting digital to

analog converter.

The SMB118 and SMB218 contain three user

programmable voltage-monitoring levels, each of which

triggers a corresponding status pin when exceeded.

Battery voltage, like all monitored voltages, is

compared against a user programmable voltage set

internally by a digital to analog converter.

The DOCK_DC pin is a power input pin that can be

used to power the SMB118 and SMB218, and also to

indicate the presence, and level, of a supplemental

input like that supplied by a docking station or AC wall

adaptor. It has a user programmable threshold from

3.4-4.8 volts at 200mV increments. When the user

programmable voltage level for this pin is exceeded,

continuously, for a de-bounced period in excess of 100

ms the DC_IN pin will be asserted.

When asserted, the POWER_FAIL pin is latched and

will not be released as long as the voltage on the

battery is below the POWER_FAIL level. Once the

voltage on the battery has risen above the

POWER_FAIL level one of three conditions may clear

the latch and allow the POWER_FAIL pin to be

released: if the nBATT_FAULT output pin is asserted

and released, if the DC_IN output pin is asserted, and

finally if an I2C POWER FAIL CLEAR command is

issued. Once one of these conditions has been met, the

POWER_FAIL pin will be released after a power-fail

timeout period (tPFTO) of 3.0-4.5ms. The POWER_FAIL

level is user programmable from 2.55-3.6V in 150 mV

increments.

When the voltage at the VBATT pin falls below the

second user programmable level (available for SMB118

only), the active low nBATT_FAULT pin will be

asserted. This pin is not latched and is used to indicate

the impending loss of power to the SMB118. After the

nBATT_FAULT pin has been asserted, a battery fault

timeout period (tBFTO) of 3.0-4.5ms must pass in which

the battery voltage exceeds the nBATT_FAULT

threshold before it will be released. The nBATT_FAULT

threshold is user programmable from 2.55-3.6.0V at

150 mV increments.

Normally Dock DC, Power fail, and battery fault

thresholds are set in descending order respectively.

Upon assertion of either the nBATT_FAULT or

POWER_FAIL pin the SMB118 and SMB218 can be

programmed to respond in one of three ways, they may

perform: a power-off operation, a force-shutdown

operation, or take no action. When programmed to

perform a power-off or force-shutdown operation the

devices can optionally be programmed to latch the

outputs off until the power on pin is toggled or an I2C

power-on command is issued.

LDO STANDBY VOLTAGE

The LDO has a programmable output voltage from 1.5V

to 3.75V. It is capable of supplying up to 75mA (typical)

and has UV and OV monitoring levels with

corresponding fault responses. The channel 2 LDO can

be sequenced on in any of the six sequence positions,

and can be enabled and disabled at any time.

OUTPUT VOLTAGE

The PWM output voltages are set by a resistive voltage

divider from the output to the COMPA or FB node; see

Figure 4. For the Buck channels (Ch[6:4]), the voltage

divider is internal to the part and programmable. The

resistive divider may be set by adjusting a 100kΩ

resistor string with 8 taps from R1 = 20-90kΩ. For the

Boost output (Ch[1]), the resistive divider is external

and any appropriate value of R1 an R2 can be chosen.

The reference voltage that sets the output is user

programmable, and may be set anywhere from 0-1.000

volt at 4mV increments.

BATTERY CHARGER

The SMB118 and SMB218 are equipped with a fully

programmable lithium ion battery charger. The

programmable feature set includes fast and pre-charge

option, each with a programmable charge current level,

a charge termination timeout period, an over and under

temperature limit, multiple allowable recharge events,

fault logging that can be accessed via the I2C interface

and a general purpose output used to indicate the

current status of the battery.

Summit Microelectronics, Inc

2107 3.0 10/15/2008

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