SLVS787A May   2009  – June 2015 TMP816

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics
  6. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Speed Control
      2. 6.3.2 Soft-Start
      3. 6.3.3 Lock Detection
      4. 6.3.4 Current Limit
      5. 6.3.5 Speed Output
      6. 6.3.6 Drive Frequency Selection
    4. 6.4 Device Functional Modes
  7. 7 Applications and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
      3. 7.2.3 Application Curves
  8. 8 Power Supply Recommendations
  9. 9 Layout
    1. 9.1 Layout Guidelines
    2. 9.2 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Community Resources
    2. 10.2 Trademarks
    3. 10.3 Electrostatic Discharge Caution
    4. 10.4 Glossary
  11. 11Mechanical, Packaging, and Orderable Information

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6 Detailed Description

6.1 Overview

The TMP816 device is a single phase bipolar predriver which uses the hall sensor & speed control inputs for driving the single phase motor connected through H Bridge. The predriver outputs are designed for driving top side P-type devices and bottom side N-channel FETs in the bridge. Multiple protections like overcurrent, soft-start, speed control, lock detect, speed feedback and minimum speed are incorporated in the device.

6.2 Functional Block Diagram

TMP816 block_dgm_lvs787.gif

6.3 Feature Description

6.3.1 Speed Control

The speed control functionality is obtained by VTH pin of the device. For pulsed inputs user can supply a 20-kHz to 100-kHz frequency input (20 kHz to 50 kHz recommended on the pin with a current limiting resistor in between. If not used, this pin needs to be connected to ground for full speed.)

6.3.2 Soft-Start

Soft-Start Time can be adjusted using the S-S pin. Connect this capacitor between 6VREG and S-S Pin. Connected to GND if not used.

6.3.3 Lock Detection

When the rotor is locked by external means or load conditions, The Lock detection feature helps to protect the circuit by not allowing the current to rise beyond control. A hiccup mechanism is also provided. The Lock detection is enabled by a connection to the lock detection capacitor. The constant current charge and discharge circuits cause drive stop when the pin voltage rises to 3.8V and enabling it back when voltage reached to 1.8V.

If lock detection feature is not desired in the application, this pin needs to be connected to ground.

6.3.4 Current Limit

Current limit resistor is connected in a return path of H Bridge connection. This input is connected to the SENSE pin where the Current is limited when the voltage across this resistor crosses the voltage at VLIM Pin.

If not used, this pin needs to be connected to ground.

6.3.5 Speed Output

The speed of the motor while running can be observed at the FG pin which is an open collector output and needs to be pulled high for using it.

6.3.6 Drive Frequency Selection

The P-channel switches in the device are switched with higher frequency whose duty cycle is decided by the speed control input. The frequency of the operation can be decided by the capacitor connected at the CPWM pin.

TMP816 ai_ctrl_timg_lvs787.gif
A. Minimum speed setting (stop) mode
PWM-IN input is filtered to generate the VTH voltage. At low speed, the fan rotates with the minimum speed set with RMI during low speed. If the minimum speed is not set (RMI = 6VREG), the fan stops.
B. Low ↔ high-speed mode
PWM control is made through comparison of oscillation and VTH voltages with CPWM changing between 1.6 V ↔ 4.6 V.
Upper and lower TRs are turned ON when the VTH voltage is higher. The upper output TR is turned OFF when the VTH voltage is lower, and the coil current is regenerated in the lower TR. Therefore, as the VTH voltage lowers, the output ON duty increases, increasing the coil current and raising the motor speed. The rotation speed is fed back by the FG output.
C. Full speed mode
The full-speed mode becomes effective with the VTH voltage of 1.65 V or less. (VTH must be equal to GND when the speed control is not used.)
D. PWM-IN input disconnection mode
When the PWM-IN input pin is disconnected, VTH becomes 1.65 V or less and the output enables full drive at 100%. The fan runs at full speed (see Figure 5).
Figure 2. Control Timing
TMP816 ss_timing_vth_lt_rmi_lvs787.gifFigure 3. Soft-Start Control Timing (VTH < RMI Voltage)
TMP816 ss_timing_vth_gt_rmi_lvs787.gifFigure 4. Soft-Start Control Timing (VTH > RMI Voltage)

6.4 Device Functional Modes

Table 1. Truth Table

IN– IN+ CT OUT1P OUT1N OUT2P OUT2N FG RD MODE
H L L L – – H L L OUT1 → 2 drive
L H – H L – OFF OUT2 → 1 drive
H L H OFF – – H L OFF Lock protection
L H – H OFF – OFF
VTH CPWM IN– IN+ OUT1P OUT1N OUT2P OUT2N MODE
L H H L L – – H OUT1 → 2 Drive
L H – H L – OUT2 → 1 Drive
H L H L OFF – – H During rotation, regeneration in lower TR
L H – H OFF –