MAX17135
Multi-Output DC-DC Power Supply with
VCOM Amplifier and Temperature Sensor for
E-Paper Applications
14
Typical Operating Circuit
The IC’s typical operating circuit (Figure 2) generates
Q15V source-driver supplies and +22V and -20V gate-
driver supplies for E-paper displays. The input voltage
range for the IC is from 2.7V to 5.5V. Figure 3 shows the
functional diagram. Table 1 lists recommended compo-
nents and Table 2 lists contact information for compo-
nent suppliers.
Detailed Description
Source-Driver Power Supplies
The source-driver power supplies consist of a boost
converter and an inverting buck-boost converter that
generate +15V (+17V max) and -15V (-17V max),
respectively, and can deliver up to 200mA. The positive
source-driver power supply’s regulation voltage (VPOS)
can be set using the external resistor-divider network
shown in Figure 2, or can be programmed through the
I2C interface connecting FBP to GND before power-up.
The negative source-driver supply voltage (VNEG) is
automatically tightly regulated to -VPOS within Q50mV.
VNEG cannot be adjusted independently of VPOS.
Gate-Driver Power Supplies
The positive gate-driver power supply (GVDD) generates
+22V (+40V max) and the negative gate-driver power
supply (GVEE) generates -20V (-40V max). Both supplies
can supply up to 20mA current. The GVDD and GVEE
regulation voltages are both set by using the external
resistor-divider networks shown in Figure 2.
VCOM Amplifier
The IC features a negative output VCOM amplifier whose
voltage is programmed through an I2C interface. An
internal 8-bit digital-to-analog converter (DAC) allows
for a wide VCOM output range of -0.5V to -3.05V and a
10mV change per DAC step. The user can store the DAC
setting in nonvolatile memory. On power-up, the nonvola-
tile memory sets the DAC to the last stored setting.
Temperature Sensor
The IC includes a temperature sensor that reads the
internal IC temperature and the external panel tem-
perature with the use of an external temperature-sensing
diode. Temperature output data is supplied through I2C.
An analog-to-digital converter (ADC) converts the tem-
perature data to 9 bits, two’s-complement format and
stores the conversion results in separate temperature
registers.
Fault Protection
The IC has robust fault and overload protection. If any
of the GVEE, NEG, POS, or GVDD outputs fall more
than 80% (typ) below their intended regulation voltage
for more than 50ms (typ), or if a short-circuit condition
occurs on any output for any duration, then all outputs
latch off and FLT is asserted low. The fault condition is
set in the Fault register, which can be read through the
I2C interface.
True Shutdown
The IC completely disconnects the loads from the input
when in shutdown mode. In most boost converters, the
external rectifying diode and inductor form a DC current
path from the battery to the output. This can drain the
battery even in shutdown if a load was connected at
the boost-converter output. The device has an internal
switch at POS. When this switch turns off during shut-
down, there is no DC path from the input to POS.
Table 1. Component List
Table 2. Component Suppliers
DESIGNATION DESCRIPTION
C2, C6
10FF Q10%, 6.3V X7R ceramic
capacitors (0805)
TDK C2012X7R0J106K
C3, C4, C5,
C7, C17–C20
4.7FF Q10%, 25V X7R ceramic
capacitors (1206)
Murata GRM31CR71E475KA88L
D1, D2 30V, 1A single Schottky diodes (SOD123)
ON Semiconductor MBR130T1
D3, D4 Dual small-signal diodes (SOT23)
Fairchild MMBD4148SE
L1, L2 4.7FH, 1.5A, 45mI inductors
TOKO A915AY-4R7M
Q1 40V npn transistor (SOT23)
Fairchild MMBT3904
SUPPLIER WEBSITE
Fairchild Semiconductor www.fairchildsemi.com
Murata Electronics North
America, Inc. www.murata-northamerica.com
ON Semiconductor www.onsemi.com
TDK Corp. www.component.tdk.com
TOKO America, Inc. www.tokoam.com