The TLC5947 is a 24-channel, constant-current sink LED driver. Each channel is individually adjustable with 4096 pulse-width modulated (PWM) steps. PWM control is repeated automatically with the programmed grayscale (GS) data. GS data are written via a serial interface port. The current value of all 24 channels is set by a single external resistor.
The TLC5947 has a thermal shutdown (TSD) function that turns off all output drivers during an over-temperature condition. All of the output drivers automatically restart when the temperature returns to normal conditions.
PART NUMBER | PACKAGE | BODY SIZE (NOM) |
---|---|---|
TLC5947 | HTSSOP (32) | 11.00 mm × 6.20 mm |
VQFN (32) | 5.00 mm × 5.00 mm |
Changes from A Revision (September 2008) to B Revision
PIN | I/O | DESCRIPTION | ||
---|---|---|---|---|
NAME | RHB NO. | DAP NO. | ||
BLANK | 30 | 2 | I | Blank (all constant-current outputs off). When BLANK is high, all constant-current outputs (OUT0 through OUT23) are forced off, the grayscale PWM timing controller initializes, and the grayscale counter resets to '0'. When BLANK is low, all constant-current outputs are controlled by the grayscale PWM timing controller. |
GND | 29 | 1 | — | Power ground |
IREF | 27 | 31 | I/O | This pin sets the constant-current value. OUT0 through OUT23 constant sink current is set to the desired value by connecting an external resistor between IREF and GND. |
OUT0 | 1 | 5 | O | Constant-current output. Multiple outputs can be tied together to increase the constant-current capability. Different voltages can be applied to each output. |
OUT1 | 2 | 6 | O | Constant-current output |
OUT2 | 3 | 7 | O | Constant-current output |
OUT3 | 4 | 8 | O | Constant-current output |
OUT4 | 5 | 9 | O | Constant-current output |
OUT5 | 6 | 10 | O | Constant-current output |
OUT6 | 7 | 11 | O | Constant-current output |
OUT7 | 8 | 12 | O | Constant-current output |
OUT8 | 9 | 13 | O | Constant-current output |
OUT9 | 10 | 14 | O | Constant-current output |
OUT10 | 11 | 15 | O | Constant-current output |
OUT11 | 12 | 16 | O | Constant-current output |
OUT12 | 13 | 17 | O | Constant-current output |
OUT13 | 14 | 18 | O | Constant-current output |
OUT14 | 15 | 19 | O | Constant-current output |
OUT15 | 16 | 20 | O | Constant-current output |
OUT16 | 17 | 21 | O | Constant-current output |
OUT17 | 18 | 22 | O | Constant-current output |
OUT18 | 19 | 23 | O | Constant-current output |
OUT19 | 20 | 24 | O | Constant-current output |
OUT20 | 21 | 25 | O | Constant-current output |
OUT21 | 22 | 26 | O | Constant-current output |
OUT22 | 23 | 27 | O | Constant-current output |
OUT23 | 24 | 28 | O | Constant-current output |
SCLK | 31 | 3 | I | Serial data shift clock. Schmitt buffer input. Data present on the SIN pin are shifted into the shift register with the rising edge of the SCLK pin. Data are shifted to the MSB side by 1-bit synchronizing of the rising edge of SCLK. The MSB data appears on SOUT at the falling edge of SCLK. A rising edge on the SCLK input is allowed 100 ns after an XLAT rising edge. |
SIN | 32 | 4 | I | Serial input for grayscale data |
SOUT | 25 | 29 | O | Serial data output. This output is connected to the shift register placed after the MSB of the grayscale shift register. Therefore, the MSB data of the grayscale shift register appears at the falling edge of SCLK. This function reduces the data shifting errors caused by small timing margins between SIN and SCLK. |
VCC | 28 | 32 | — | Power-supply voltage |
XLAT | 26 | 30 | I | The data in the grayscale shift register are moved to the grayscale data latch with a low-to-high transition on this pin. When the XLAT rising edge is input, all constant-current outputs are forced off until the next grayscale display period. The grayscale counter is not reset to zero with a rising edge of XLAT. |
MIN | MAX | UNIT | |||
---|---|---|---|---|---|
VCC | Supply voltage: VCC | –0.3 | 6.0 | V | |
IO | Output current (dc) | OUT0 to OUT23 | 38 | mA | |
VI | Input voltage | SIN, SCLK, XLAT, BLANK | –0.3 | VCC + 0.3 | V |
VO | Output voltage | SOUT | –0.3 | VCC + 0.3 | V |
OUT0 to OUT23 | –0.3 | 33 | V | ||
TJ(MAX) | Operating junction temperature | 150 | °C | ||
Tstg | Storage temperature | –55 | 150 | °C |
VALUE | UNIT | ||||
---|---|---|---|---|---|
V(ESD) | Electrostatic discharge | Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins(1) | ±2500 | V | |
Charged device model (CDM), per JEDEC specification JESD22-C101, all pins(2) | ±500 |
MIN | NOM | MAX | UNIT | |||
---|---|---|---|---|---|---|
DC CHARACTERISTICS: VCC = 3 V to 5.5 V | ||||||
VCC | Supply voltage | 3.0 | 5.5 | V | ||
VO | Voltage applied to output OUT0 to OUT23 | 30 | V | |||
VIH | High-level input voltage | 0.7 × VCC | VCC | V | ||
VIL | Low-level input voltage | GND | 0.3 × VCC | V | ||
IOH | High-level output current SOUT | –3 | mA | |||
IOL | Low-level output current SOUT | 3 | mA | |||
IOLC | Constant output sink current OUT0 to OUT23 | 2 | 30 | mA | ||
TA | Operating free-air temperature range | –40 | 85 | °C | ||
TJ | Operating junction temperature | –40 | 125 | °C | ||
AC CHARACTERISTICS: VCC = 3 V to 5.5 V | ||||||
fSCLK | Data shift clock frequency | SCLK, Standalone operation | 30 | MHz | ||
SCLK, Duty 50%, cascade operation | 15 | MHz | ||||
TWH0 | Pulse duration | SCLK = High-level pulse width | 12 | ns | ||
TWL0 | SCLK = Low-level pulse width | 10 | ns | |||
TWH1 | XLAT, BLANK High-level pulse width | 30 | ns | |||
TSU0 | Setup time | SIN–SCLK↑ | 5 | ns | ||
TSU1 | XLAT↑–SCLK↑ | 100 | ns | |||
TSU2 | XLAT↑–BLANK↓ | 30 | ns | |||
TH0 | Hold time | SIN–SCLK↑ | 3 | ns | ||
TH1 | XLAT↑–SCLK↑ | 10 | ns |
THERMAL METRIC(1) | TLC5947 | UNIT | |
---|---|---|---|
DAP | |||
32 PINS | |||
RθJA | Junction-to-ambient thermal resistance | 32.8 | °C/W |
RθJC(top) | Junction-to-case (top) thermal resistance | 17.1 | |
RθJB | Junction-to-board thermal resistance | 17.9 | |
ψJT | Junction-to-top characterization parameter | 0.4 | |
ψJB | Junction-to-board characterization parameter | 17.8 | |
RθJC(bot) | Junction-to-case (bottom) thermal resistance | 1.3 |
PACKAGE | OPERATING FACTOR ABOVE TA = 25°C | TA < 25°C POWER RATING |
TA = 70°C POWER RATING |
TA = 85°C POWER RATING |
---|---|---|---|---|
HTSSOP-32 with PowerPAD™ soldered(1) |
42.54 mW/°C | 5318 mW | 3403 mW | 2765 mW |
HTSSOP-32 with PowerPAD not soldered(2) |
22.56 mW/°C | 2820 mW | 1805 mW | 1466 mW |
QFN-32(3) | 27.86 mW/°C | 3482 mW | 2228 mW | 1811 mW |
PARAMETER | TEST CONDITIONS | MIN | TYP | MAX | UNIT | |
---|---|---|---|---|---|---|
VOH | High-level output voltage | IOH = –3 mA at SOUT | VCC – 0.4 | VCC | V | |
VOL | Low-level output voltage | IOL = 3 mA at SOUT | 0.4 | V | ||
IIN | Input current | VIN = VCC or GND at SIN, XLAT, and BLANK | –1 | 1 | μA | |
ICC1 | Supply current (VCC) | SIN/SCLK/XLAT = low, BLANK = high, VOUTn = 1 V, RIREF = 24 kΩ | 0.5 | 3 | mA | |
ICC2 | SIN/SCLK/XLAT = low, BLANK = high, VOUTn = 1 V, RIREF = 3.3 kΩ | 1 | 6 | mA | ||
ICC3 | SIN/SCLK/XLAT = low, BLANK = low, VOUTn = 1 V, RIREF = 3.3 kΩ, GSn = FFFh | 15 | 45 | mA | ||
ICC4 | SIN/SCLK/XLAT = low, BLANK = low, VOUTn = 1 V, RIREF = 1.6 kΩ, GSn = FFFh | 30 | 90 | mA | ||
IOLC | Constant output current | All OUTn = ON, VOUTn = 1 V, VOUTfix = 1 V, RIREF = 1.6 kΩ |
27.7 | 30.75 | 33.8 | mA |
IOLK | Output leakage current | BLANK = high, VOUTn = 30 V, RIREF = 1.6 kΩ, At OUT0 to OUT23 |
0.1 | μA | ||
ΔIOLC | Constant-current error (channel-to-channel)(1) |
All OUTn = ON, VOUTn = 1 V, VOUTfix = 1 V, RIREF = 1.6 kΩ, At OUT0 to OUT23 |
–4% | ±2% | 4% | |
ΔIOLC1 | Constant-current error (device-to-device)(2) |
All OUTn = ON, VOUTn = 1 V, VOUTfix = 1 V, RIREF = 1.6 kΩ |
–7% | ±2% | 7% | |
ΔIOLC2 | Line regulation(3) | All OUTn = ON, VOUTn = 1 V, VOUTfix = 1 V, RIREF = 1.6 kΩ, At OUT0 to OUT23 |
±1 | ±3 | %/V | |
ΔIOLC3 | Load regulation(4) | All OUTn = ON, VOUTn = 1 V to 3 V, VOUTfix = 1 V, RIREF = 1.6 kΩ, At OUT0 to OUT23 | ±2 | ±6 | %/V | |
TDOWN | Thermal shutdown threshold | Junction temperature(5) | 150 | 162 | 175 | °C |
THYS | Thermal error hysteresis | Junction temperature(5) | 5 | 10 | 20 | °C |
VIREF | Reference voltage output | RIREF = 1.6 kΩ | 1.16 | 1.20 | 1.24 | V |
PARAMETER | TEST CONDITIONS | MIN | TYP | MAX | UNIT | |
---|---|---|---|---|---|---|
tR0 | Rise time | SOUT | 10 | 15 | ns | |
tR1 | OUTn | 15 | 40 | ns | ||
tF0 | Fall time | SOUT | 10 | 15 | ns | |
tF1 | OUTn | 100 | 300 | ns | ||
fOSC | Internal oscillator frequency | 2.4 | 4 | 5.6 | MHz | |
tD0 | Propagation delay time | SCLK↓ to SOUT | 15 | 25 | ns | |
tD1 | BLANK↑ to OUT0 sink current off | 20 | 40 | ns | ||
tD2 | OUT0 current on to OUT1/5/9/13/17/21 current on | 15 | 24 | 33 | ns | |
tD3 | OUT0 current on to OUT2/6/10/14/18/22 current on | 30 | 48 | 66 | ns | |
tD4 | OUT0 current on to OUT3/7/11/15/19/23 current on | 45 | 72 | 99 | ns |
The TLC5947 is a 24-channel, constant-current sink driver. Each channel has an individually-adjustable, 4096-step, PWM grayscale (GS) brightness control. The GS data is input through a serial interface port.
The TLC5947 has a 30-mA current capability. The maximum current value of all channels is determined by an external resistor.
The TLC5947 can work without external CLK signals because the device is integrated with a 4-MHz internal oscillator.
The device has a thermal shutdown (TSD) function that turns off all output drivers at over temperature conditions. All of the output drivers automatically restart when the temperature returns to normal conditions.
Each constant-current sink output OUT0–OUT23 (OUTn) turns on (starts to sink constant current) at the fifth rising edge of the grayscale internal oscillator clock after the BLANK signal transitions from high to low if the grayscale data latched into the grayscale data latch are not zero. After turn-on, the number of rising edges of the internal oscillator is counted by the 12-bit grayscale counter. Each OUTn output is turned off once its corresponding grayscale data values equal the grayscale counter or the counter reaches 4096d (FFFh). The PWM control operation is repeated as long as BLANK is low. OUTn is not turned on when BLANK is high. The timing is shown in Figure 18. All outputs are turned off at the XLAT rising edge. After that, each output is controlled again from the first clock of the internal oscillator for the next display period, based on the latest grayscale data.
When the IC is powered on, the data in the grayscale data shift register and latch are not set to default values. Therefore, grayscale data must be written to the GS latch before turning on the constant-current output. BLANK should be at a high level when powered on to keep the outputs off until valid grayscale data are written to the latch. This avoids the LED being randomly illuminated immediately after power-up. If having the outputs turn on at power-up is not a problem for the application, then BLANK does not need to be held high. The grayscale functions can be controlled directly by grayscale data writing, even though BLANK is connected to GND.
This function can repeat the total display period without any timing control signal, as shown in Figure 19.
The thermal shutdown (TSD) function turns off all constant-current outputs immediately when the IC junction temperature exceeds the high temperature threshold (T(TEF) = +162° C, typ). The outputs will remain disabled as long as the over-temperature condition exists. The outputs are turned on again at the first clock after the IC junction temperature falls below the temperature of T(TEF) – T(HYS). Figure 20 shows the TSD operation.
Large surge currents may flow through the IC and the board on which the device is mounted if all 24 LED channels turn on simultaneously at the start of each grayscale cycle. These large current surges could introduce detrimental noise and electromagnetic interference (EMI) into other circuits. The TLC5947 turns on the LED channels in a series delay, to provide a current soft-start feature. The output current sinks are grouped into four groups of six channels each. The first group is OUT0, 4, 8, 12, 16, 20; the second group is OUT1, 5, 9, 13, 17, 21; the third group is OUT2, 6, 10, 14, 18, 22; and the fourth group is OUT3, 7, 11, 15, 19, 23. Each group turns on sequentially with a small delay between groups; see Figure 3. Both turn-on and turn-off are delayed.
The TLC5947 has a grayscale (GS) data shift register and data latch. Both the GS data shift register and latch are 288 bits long and are used to set the PWM timing for the constant-current driver. Table 1 shows the on duty cycle for each GS data. Figure 21 shows the shift register and data latch configuration. The data at the SIN pin are shifted to the LSB of the shift register at the rising edge of the SCLK pin; SOUT data are shifted out on the falling edge of SCLK. The timing diagram for data writing is shown in Figure 22. The driver on duty is controlled by the data in the GS data latch.
GS DATA (Binary) |
GS DATA (Decimal) |
GS DATA (Hex) |
DUTY OF DRIVER TURN-ON TIME (%) |
---|---|---|---|
0000 0000 0000 | 0 | 000 | 0.00 |
0000 0000 0001 | 1 | 001 | 0.02 |
0000 0000 0010 | 2 | 002 | 0.05 |
0000 0000 0011 | 3 | 003 | 0.07 |
— | — | — | — |
0111 1111 1111 | 2047 | 7FF | 49.98 |
1000 0000 0000 | 2048 | 800 | 50.00 |
1000 0000 0001 | 2049 | 801 | 50.02 |
— | — | — | — |
1111 1111 1101 | 4093 | FFD | 99.93 |
1111 1111 1110 | 4094 | FFE | 99.95 |
1111 1111 1111 | 4095 | FFF | 99.98 |
GS data are transferred from the shift register to the latch by the rising edge of XLAT. When powered up, the data in the grayscale shift register and data latch are not set to default values. Therefore, grayscale data must be written to the GS latch before turning on the constant-current output. BLANK should be at a high level when powered on to avoid falsely turning on the constant-current outputs due to random values in the latch at power-up. All of the constant-current outputs are forced off when BLANK is high. However, if the random values turning on at power-up is not a concern in the application, BLANK can be at any level. GS can be controlled correctly with the grayscale data writing functions, even if BLANK is connected to GND. Equation 1 determines each output on duty.
where
NOINDENT:
GS data = FFFh.