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CAT3636HV3-GT2

P1-P3P4-P6P7-P9P10-P12P13-P13
CAT3636
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10
Register Configuration and Programming
Table 6. REGISTER ADDRESS AND DATA
Register
Address
Pulses
Description Bits
DATA Pattern
Bit 3 Bit 2 Bit 1 Bit 0
REG1 1 Bank Enable and IMODE 4 IMODE ENA ENB ENC
REG2 2 Global Current Setting 4
See Table 8 for values
REG3 3 Bank A Current Setting 4
REG4 4 Bank B Current Setting 4
REG5 5 Bank C Current Setting 4
REG6 6 Return Lockout 1 RTLKO
Register REG1 allows to set the mode and select the pairs
of LEDs to be turned on. A low LED current mode exists to
allow for very low current operation under 4 mA per
channel. If IMODE equals 1, the high current range is
selected up to 32 mA. If IMODE is set to 0, all currents are
divided by 8. Each bank of LEDs (A, B or C) can be turned
on independently by setting the respective bit ENA, ENB,
ENC to 1, as shown in Table 7. For example, to enable all 6
LEDs in low current mode, REG1 is programmed to 0111
binary (9 data pulses).
Table 7. REG1 REGISTER SETTING
Data
Pulses
REG1 Value
(binary)
IMODE
Bank Enable
ENA ENB ENC
0 0000 0 − − −
1 1111 1 On On On
2 1110 1 On On −
3 1101 1 On − On
4 1100 1 On − −
5 1011 1 − On On
6 1010 1 − On −
7 1001 1 − − On
8 1000 1 − − −
9 0111 0 On On On
10 0110 0 On On −
11 0101 0 On − On
12 0100 0 On − −
13 0011 0 − On On
14 0010 0 − On −
15 0001 0 − − On
16 0000 0 − − −
Register REG2 allows to set the same current for all 6
channels. REG3, REG4, REG5 allow to set the current
respectively in banks A, B and C. The three banks can be
programmed with independent current values.
Table 8. REG2−5 CURRENT SETTING REGISTERS
Data
Pulses
REGx Value
(binary)
LED Current
IMODE = 0
LED Current
IMODE = 1
0 0000 0.0 mA 2 mA
1 1111 3.75 mA 32 mA
2 1110 3.5 mA 30 mA
3 1101 3.25 mA 28 mA
4 1100 3 mA 26 mA
5 1011 2.75 mA 24 mA
6 1010 2.5 mA 22 mA
7 1001 2.25 mA 20 mA
8 1000 2 mA 18 mA
9 0111 1.75 mA 16 mA
10 0110 1.5 mA 14 mA
11 0101 1.25 mA 12 mA
12 0100 1 mA 10 mA
13 0011 0.75 mA 8 mA
14 0010 0.5 mA 6 mA
15 0001 0.25 mA 4 mA
16 0000 0.0 mA 2 mA
REG6 contains the return lockout (RTLKO) bit. This
stops the charge pump returning to 1x mode. One pulse sets
it to 1. Two pulses or no pulses set RTLKO to 0. When
RTLKO is set to 1, the charge pump cannot automatically
return to 1x mode when in one of the charge pump modes.
The device can however move from 1x to 1.33x to 1.5x to
2x if the input voltage is not sufficient to drive the
programmed LED currents.
REG6 also triggers a charge pump reset as soon as it is
addressed. This forces the charge pump to start from 1x
mode and reassess the correct mode it should be in to drive
the LEDs most efficiently. If the input voltage has risen or
the device has been reprogrammed to other LED values, it
is recommended to trigger this reset allowing the charge
pump to run in the most efficient mode.
The CAT3636 enters a “zero current” shutdown mode if
EN/SET is held low for 1.5 ms or more. All registers are
reset back to zero when the device is placed in shutdown.
CAT3636
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11
Programming Examples
Programming 6 LEDs to 20 mAProgramming 6 LEDs to 32 mA
Programming 6 LEDs to 1 mA
CAT3636
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12
Unused LED Channels
For applications with only four or two LEDs, unused LED
banks can be disabled via the enable register internally and
left to float.
For applications with 5 LEDs or less, unused LEDs can
also be disabled by connecting the LED pin directly to
VOUT, as shown on Figure 22. If LED pin voltage is within
1 V of VOUT, then the channel is switched off and a 200 mA
test current is placed in the channel to sense when the
channel moves below VOUT – 1 V.
Figure 22. Five LED Application
Protection Mode
If an LED is disconnected, the output voltage V
OUT
automatically limits at about 5.5 V. This is to prevent the
output pin from exceeding its absolute maximum rating.
If the die temperature exceeds +150°C the driver will
enter a thermal protection shutdown mode. When the device
temperature drops by about 20°C the device will resume
normal operation.
LED Selection
LEDs with forward voltages (V
F
) ranging from 1.3 V to
5.0 V may be used with the CAT3636. Selecting LEDs with
lower V
F
is recommended in order to improve the efficiency
by keeping the driver in 1x mode longer as the battery
voltage decreases.
For example, if a white LED with a V
F
of 3.3 V is selected
over one with V
F
of 3.5 V, the CAT3636 will stay in 1x mode
for lower supply voltage of 0.2 V. This helps improve the
efficiency and extends battery life.
External Components
The driver requires two external 1 mF ceramic capacitors
for decoupling input, output, and for the charge pump. Both
capacitors type X5R and X7R are recommended for the
LED driver application. In all charge pump modes, the input
current ripple is kept very low by design and an input bypass
capacitor of 1 mF is sufficient.
In 1x mode, the device operates in linear mode and does
not introduce switching noise back onto the supply.
Recommended Layout
In charge pump mode, the driver switches internally at a
high frequency. It is recommended to minimize trace length
to all four capacitors. A ground plane should cover the area
under the driver IC as well as the bypass capacitors. Short
connection to ground on capacitors C
IN
and C
OUT
can be
implemented with the use of multiple via. A copper area
matching the TQFN exposed pad (TAB) must be connected
to the ground plane underneath. The use of multiple via
improves the package heat dissipation.
Figure 23. Recommended Layout
P1-P3P4-P6P7-P9P10-P12P13-P13

CAT3636HV3-GT2

Mfr. #:
Buy CAT3636HV3-GT2
Manufacturer:
ON Semiconductor
Description:
LED Lighting Drivers LED Driver,Quad mode,6 ch
Lifecycle:
New from this manufacturer.
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