LP5523 datasheet(39/61 Pages) TI2

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LP5523

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SNVS550E – SEPTEMBER 2009 – REVISED JANUARY 2017

Product Folder Links: LP5523

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•

74H — Bit [7] GPO

–

See description above for ENG1 MAPPING register.

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74H — Bit [0] D9

–

See description above for ENG1 MAPPING register.

75H ENG3 MAPPING LSB

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75H — Bit [7] D8 to Bit [0] D1

–

See previous description for ENG1 MAPPING register.

76H GAIN_CHANGE_CTRL

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With hysteresis and timer bits the user can optimize the charge pump performance to better meet the

requirements of the application at hand. Some applications need to be optimized for efficiency and others

need to be optimized for minimum EMI, for example.

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76H - Bits[7:6] THRESHOLD

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Threshold voltage (typical) pre-setting. Bits set the threshold voltage at which the charge-pump gain

changes from 1.5× to 1×. The threshold voltage is defined as the voltage difference between highest

voltage output (D1 to D6) and input voltage VDD: VTHRESHOLD = VDD – MAX(voltage on D1 to D6).

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If VTHRESHOLD is larger than the set value (100 mV to 400 mV), the charge pump is in 1× mode.

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00 = 400 mV

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01 = 300 mV

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10 = 200 mV

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11 = 100 mV

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NOTE

Values above are typical and should not be used as product-specification.

NOTE

Writing to threshold [7:6] bits by the user overrides factory settings. Factory settings aren't

user-accessible.

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76H - Bit [5] ADAPTIVE_TRESH_EN

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1 = Adaptive threshold enabled.0 = Adaptive threshold disabled.

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0 = Adaptive threshold disabled.

Gain-change hysteresis prevents the mode from toggling back and forth (1× -> 1.5× -> 1x...) , which would

cause ripple on VIN and LED flicker. When the adaptive threshold is enabled, the width of the hysteresis

region depends on the choice of threshold bits (see above), saturation of the current sources, charge

pump load current, PWM overlap and temperature.

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76H - Bits [4:3] TIMER

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A forced mode change from 1.5× to 1× is attempted at the interval specified with these bits. Mode change is

allowed if there is enough voltage over the LED drivers to ensure proper operation. Set FORCE_1x to 1 (see

following 76H - Bit [2] FORCE_1x) to activate this feature.

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00 = 5 ms

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01 = 10 ms

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10 = 50 ms

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11 = infinite. The charge pump switches gain from 1× mode to 1.5× mode only. The gain reset back to 1×

is enabled under certain conditions, for example in the powersave mode.

•

Activates forced mode change. In forced mode, charge pump mode change from 1.5× to 1× is attempted at

the constant interval specified with the TIMER bits.

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1 = forced-mode changes enabled

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0 = forced-mode changes disabled

LP5523 Datenblatt(PDF) 39 Page - Texas Instruments

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