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IS31BL3231-DLS2 Datasheet(PDF) 9 Page - Integrated Silicon Solution, Inc |
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IS31BL3231-DLS2 Datasheet(HTML) 9 Page - Integrated Silicon Solution, Inc |
9 / 13 page IS31BL3231 Integrated Silicon Solution, Inc. – www.issi.com 9 Rev. C, 06/12/2015 APPLICATION INFORMATION GENERAL DESCRIPTION The IS31BL3231 is a current-regulated charge pump and ideal for powering high brightness LEDs for camera flash and torch applications. CHARGE PUMP The charge pump converter boosts input supply voltage (VCC) up to a higher output voltage (VOUT) to drive LED. The charge pump converter only requires three external components: supply decoupling capacitor, output bypass capacitor and flying capacitor. Choose low ESR capacitors to ensure the best operating performance and place the capacitors as close as possible to the IS31BL3231. The charge pump will start up automatically to offer a higher output voltage when VFB is lower than the setting value. CURRENT SETTING The LED current is set by the external resister, RFB, following the Equation (1) below. FB FB LED R V I / (1) VFB is calculated by the Equation (2) when IS31BL3231 operates in the Flash Mode. VFB is set in the Table 1 when IS31BL3231 operates in the Torch Mode. OPERATING MODE FLASH MODE By pulling the FLASH pin to high, IS31BL3231 operates in the Flash Mode. VFB is set by the RSET. k R V V SET FB 2 . 11 / 25 . 1 (2) For example, in Figure 1, RFB = 0.22Ω, RSET = 88.7kΩ, So, mV k k V V FB 158 2 . 11 7 . 88 / 25 . 1 mA mV I LED 718 22 . 0 / 158 The maximum VFB shouldn’t be over 550mV or the actual current will be large difference from then calculated current. TORCH MODE By pulling the FLASH pin to low, IS31BL3231 operates in the Torch Mode. The VFB is controlled by Pulse Count Control (PCC wire) serial interface. The interface records rising edges of the EN pin and decodes them into 8 different states. The 8 voltage level settings available are indicated in Table 1. Table 1 VFB Control Pulse VFB (Typ.) ILED (Typ.) RFB = 0.22Ω RFB = 1Ω 1 50mV 227mA 50mA 2 60mV 273mA 60mA 3 70mV 318mA 70mA 4 85mV 386mA 85mA 5 100mV 455mA 100mA 6 120mV 545mA 120mA 7 140mV 636mA 140mA ≥ 8 170mV 773mA 170mA TIMING CONTROL The EN pin should be configured as the Figure 11. tLAT is the latch time. High level should be at last tLAT to active the pulse signal. tOFF is the shutdown time. EN pin is pulled low at last tOFF the IC will be shutdown. Figure 11 EN pin timing THERMAL PROTECTION The IS31BL3231 has a thermal protection circuit that will shut down the chip if the die temperature rises above the thermal limit until the temperature falls down. |
Similar Part No. - IS31BL3231-DLS2 |
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Similar Description - IS31BL3231-DLS2 |
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